Qatar Survey Manual

Qatar Survey Manual – Table of Contents

Content

Page

Preface 1.1 Introduction 1.2 Purpose 1.3 Scope 1.4 Acronyms, Definitions and Abbreviations 1.5 Acknowledgement

1 1 1 2 3

Chapter 1 – Control Survey Abbreviations 1.1.0 Datum 1.1.1 Reference Ellipsoids 1.1.2 Geodetic Datum 1.1.3 Vertical Control Datum 1.1.4 Map Projection 1.1.5 Geoid Model – Qatar95 1.2.0 Standards 1.2.1 Introduction 1.2.2 Order – Horizontal Control 1.2.3 Order – Vertical Control 1.2.4 Instructions and Guidelines for Control Surveys 1.2.4.1 Control Survey 1.2.4.2 Control Survey Returns 1.2.4.3 Digital Data Structure (To be used for CGIS Data Backing up requirements) 1.2.5 Specification for Surveys and Reductions 1.2.5.1 Electronic Distance Measurement – EDM 1.2.5.2 Horizontal Angle Measurement 1.2.5.3 Spirit, Auto or Digital Leveling 1.2.5.4 EDM Height Traversing 1.2.5.5 Trigonometric Heighting 1.2.5.6 GNSS Heighting 1.2.5.7 Decimal Places for Height Values 1.2.5.8 Global Navigation Satellite System (GNSS) 1.2.5.9 Triangulation and Trilateration Surveys 1.2.6 Validation of GNSS Equipment 1.2.7 Calibration of Electronic Distance Meter 1.2.8 Continuously Operation Reference Stations (CORS) 1.2.9 Monumentation of Control Points References Appendix 1A – Sample Transformation Calculations Appendix 1B – Monument Types Appendix 1C – EDM Calibration Measurements Appendix 1D – Horizontal and Vertical Angle Observations

14 15 16 18 19 22 25 25 25 25 37 38 42 44 45 47 48 50 76 77

Chapter 2 – Cadastral Survey Abbreviations 2.1.0 Governing and Administrative Authority for Cadastral Survey 2.1.1 Definition and Types of Cadastral Land 2.1.2 Types of Cadastral Survey 2.1.3 Types of Boundary Limits 2.1.4 Power of Director (GSD) 2.1.5 Duties of Director (GSD) 2.1.6 Committee on the Admission of Engineers (CAE) 2.1.7 International and Local Company Registration/Accreditation Requirements 2.1.8 Accreditation of Surveyors 2.2.0 Survey Requirements for Cadastral Land

81 82 82 82 83 83 83 83 84 87 87

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2.3.0

Survey of Land Parcels 2.3.1 Coordinated Cadastre 2.3.2 Survey Datum 2.3.3 Parcel, Beacon & Parcel Numbers 2.3.3.1 Application for Parcel, Beacon & PD Numbers 2.3.3.2 Parcel and Beacon Numbering System 2.3.4 Numbering of Temporary Controls (TC) 2.3.5 Survey Control Monuments 2.3.6 Guidelines for Using GNSS in Cadastral Surveys 2.3.7 Boundary Limits of Cadastral Boundary 2.3.7.1 Area 2.3.7.2 Accuracy Specifications for Setting Out 2.3.8 Authorized Marks 2.3.8.1 Types of Marks 2.3.8.2 Feature Codes for Cadastral Marks 2.3.9 Authorized Plan Forms 2.3.10 Land Cadastral Plan 2.3.11 Drawing Specifications for Land Cadastral Plan 2.3.12 Information to be Shown on Land Cadastral Plan 2.3.13 Survey Report 2.3.14 Quality Control of Cadastral Surveys 2.3.14.1 Processes of Quality Control 2.3.14.2 Surveyors’ Check List 2.4.0 Strata Survey 2.4.1 Strata Cadastral Parcel Numbering System 2.4.2 Administrative Procedures 2.4.3 Field Survey Procedures 2.4.4 Strata Cadastral Plan 2.4.5 Drawing Specifications for Strata Cadastral Plan 2.4.6 Information to be Shown on Strata Cadastral Plan 2.4.7 Deliverable Requirements for Cadastral Strata Survey 2.5.0 Encroachment 2.5.1 Encroachments Discovered in Cadastral Surveys 2.5.2 Reporting Encroachments Appendix 2A(a) – Sample Property Documents Appendix 2A(b) – Sample Property Documents Appendix 2B – Sample Property Documents (Strata) Appendix 2C – Request for Parcel, Beacon and PD numbers Appendix 2D – Cadastral Surveys Features Codes Appendix 2E – Form to Report Encroachment

87 88 88 88 88 88 89 89 90 92 92 92 92 92 94 94 94 94 95 96 97 97 98 99 99 99 99 100 101 101 103 103 103 103 104 105 106 107 108 118

Chapter 3 – Topographic Survey Abbreviations 3.1.0 Introduction 3.2.0 Topographic Mapping Accuracy 3.3.0 Specifications 3.3.1 Total Station Observations for Topographic Surveys 3.3.2 3D Terrestrial Laser Scanners 3.4.0 Topographic Survey Data Flow 3.5.0 Basic Definitions of Geospatial Data Used in CAD or GIS Databases 3.6.0 Data Collection and Processing Procedure for Topographic Surveys 3.7.0 CAD Drawing Standard 3.7.1 Introduction 3.7.2 Organization and Naming of CAD Files 3.7.3 Level/Layer Assignments 3.7.4 Standard Symbology 3.8.0 Specifications for Topographic Surveys of Engineering and Construction Nature 3.9.0 Preparation of Survey Plan

119 120 120 122 122 124 126 127 128 129 129 129 133 138 139 142

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Qatar Survey Manual – Table of Contents

3.10.0 Preparation of Survey Report References Appendix 3A – Template Specification for Collection of Point Cloud Data using Terrestrial Laser Scanner Appendix 3B – List of Type-of-Work Codes by Discipline Appendix 3C – List of Type-of-Work Codes in Alphabetical Order Appendix 3D – List of Main Elements in Alphabetical Order Appendix 3E – List of Recommended Sub-Elements in Alphabetical Order Appendix 3F – Topographic Survey Feature Appendix 3G – PWA Topographic Feature Library Appendix 3H – Graphic Concepts Appendix 3I – Example of Q-TEL GFCODE

146 153 156 159 162 172 177 181 184

Chapter 4 – Hydrographic Survey Abbreviations 4.1.0 Introduction 4.2.0 Standards of Competence for Hydrographic Surveyors 4.3.0 Classification of Surveys 4.3.1 Special Order Surveys 4.3.2 Order 1a Surveys 4.3.3 Order 1b Surveys 4.3.4 Classification Table – Qatar Standards for Hydrographic Surveys 4.4.0 Geodetic Parameters 4.5.0 Positioning 4.5.1 Coastline Position 4.5.2 Wharf, Jetty, Dolphin, Ramp & Breakwater Position 4.5.3 Conspicuous Object and Beacon Position 4.5.4 Drying Rock and Obstruction Position 4.5.5 Navigational & Mooring Buoys Position 4.5.6 Sounding Position – GNSS Positioning 4.6.0 Depth Acquisition 4.6.1 By Single Beam Echo Sounder 4.6.1.1 Calibration of Dual Frequency Echo Sounder 4.6.1.2 Coverage of surveys 4.6.1.3 Logging of Digital Depths 4.6.1.4 Shoal Soundings 4.6.1.5 Data Processing 4.6.2 By Multibeam Echo Sounding 4.6.2.1 Calibration 4.6.2.2 Coverage and Detection of Seabed Features 4.6.2.3 Multibeam Back Scatter Parameters 4.6.2.4 Tidal Reduction 4.6.2.5 Acquisition and Processing 4.6.3 By Bathymetric LIDAR 4.6.3.1 Calibration 4.6.3.2 Spot Density & Depths at Chart Datum 4.6.3.3 Navigational Hazards Detection 4.7.0 Sea Floor Classification 4.7.1 By Side Scan Sonar 4.7.2 Classification by Back Scattering Echo Return 4.7.3 Seabed Sampling 4.8.0 Tidal Levels 4.8.1 Calibration of Tide Gauges 4.8.2 Setting Up of Tide Gauge 4.8.3 Chart Datum 4.8.4 Harmonic Analysis and Tidal Prediction 4.8.5 Relative Tidal Heights 4.8.6 Accuracy Standard

185 186 186 186 187 187 187 188 190 191 191 191 191 191 192 192 192 193 193 193 194 194 194 194 194 195 195 195 196 196 197 197 197 197 199 199 199 199 199 200 200 201 201 201

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4.9.0

Currents (Tidal Streams) 4.9.1 Long Term Current Recording 4.9.2 Accuracy Standard 4.10.0 Sea Floor Search 4.10.1 By Multibeam Echo Sounder (MBES) 4.10.2 By Side Scan Sonar 4.10.3 By Mechanical Drag Sweep 4.10.4 By Magnetometer Survey 4.10.5 Detection of Debris and Obstructions in Navigational Channels and Anchorages 4.10.6 Submarine Cables and Pipelines 4.11.0 Data Rendering 4.11.1 Survey Data to be Rendered 4.11.2 Report of Survey 4.11.3 Digital Records 4.11.4 Analogue Records Glossary

201 201 202 202 202 202 205 209 209 209 209 209 210 212 212 213

Chapter 5 – Construction Survey Abbreviations 5.1.0 Introduction 5.2.0 Accuracy Standards 5.3.0 Compliance with Contract Specifications 5.4.0 Method of Survey 5.5.0 Field Survey Record 5.6.0 Survey Computation 5.7.0 Preparation of Setting Out Plan 5.8.0 Submission of Plans and Survey Records 5.9.0 Guideline on Setting Out Survey 5.10.0 Permitted Deviations for Setting Out Survey 5.11.0 Specifications and Work Procedures for Construction Surveys 5.11.1 Specifications for Construction Works 5.11.2 Work Procedures for Construction Works 5.11.3 Working Practice in Construction Works 5.12.0 Survey Marker 5.13.0 Plan Flow associated with Construction Survey References Appendix 5A – Guidelines on Accuracy of Survey Instrument

217 218 218 218 219 219 219 219 220 220 221 222 222 222 223 223 223 224 225

Chapter 6 – Gravimetric Survey 6.1.0 Introduction 6.1.1 Existing geoid models for Qatar 6.1.2 Requirements for a Gravity Field for a New Geoid Model for Qatar 6.2.0 Terrestrial Absolute and Relative Gravimetry 6.2.1 Introduction to Gravity Networks 6.2.1.1 The Global Network IGSN 71 6.2.1.2 National or Regional Networks 6.2.1.3 Local Surveys 6.2.2 Instrumentation 6.2.2.1 Absolute Gravimeters 6.2.2.2 Relative Gravimeters (measuring changes in g) 6.2.3 Field Procedures 6.2.4 Office Procedures 6.2.4.1 Factors which Affect the Measurement of Gravity – g 6.2.4.2 The Precision of ∆g 6.2.4.3 Gravity Data Validation 6.2.4.4 Gravity Data Format 6.3.0 Airborne Gravimetry 6.3.1 Airborne Gravity Systems

229 229 230 230 230 230 230 231 232 232 232 233 234 234 236 237 238 238 238

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6.3.2 6.3.3

6.3.4 References

Field Techniques Office Techniques 6.3.3.1 Processing the GPS Data 6.3.3.2 Processing the Airborne Gravity Data Final Comments

Chapter 7 – Digital Mapping Abbreviations 7.1.0 Digital Mapping General Specifications 7.1.1 General 7.1.2 Mapping Accuracy Standards 7.1.3 Projection, Datum, Coordinate System 7.1.4 Project Extent 7.2.0 Manual and Specifications for Aerial Photography with Large Format Digital Camera 7.2.1 Background 7.2.1.1 Choice of Reference Scale 7.2.1.2 Choice of Flying Height 7.2.1.3 Planning for Digital Aerial Camera 7.2.2 Specifications 7.2.2.1 General 7.2.2.2 Flight Specifications 7.2.2.2.1 General 7.2.2.2.2 Flight Logs 7.2.2.2.3 Weather 7.2.2.2.4 Coverage 7.2.2.2.4.1 Flight Lines 7.2.2.2.4.2 Flying Height 7.2.2.2.4.3 Overlap 7.2.2.3 Camera 7.2.2.4 ABGPS and IMU 7.2.2.5 Data Characteristics 7.2.2.6 Documentation 7.2.2.7 Deliverables 7.3.0 Specifications for Ground Control for Photogrammetric Mapping 7.3.1 General 7.3.1.1 Projection, Datum, Coordinate System 7.3.2 Ground Control Requirements 7.3.2.1 Basic Control 7.3.2.2 Photo Control 7.3.2.2.1 Characteristics 7.3.2.2.2 Horizontal Photo Control 7.3.2.2.3 Vertical Photo Control 7.3.2.2.4 GPS for Horizontal and Vertical Control 7.3.2.3 Control Point Distribution 7.3.3 Marking Photo Control 7.3.3.1 Premarking 7.3.3.2 Postmarking 7.3.3.3 Airborne Global Positioning System (ABGPS) and Inertial Measuring Unit (IMU) Control 7.3.4 Deliverables Annex 7A – Ground Control Point Diagram for Aerial and Satellite Imagery 7.4.0 Specifications for Aerial Triangulation 7.4.1 General 7.4.2 Aerial Triangulation 7.4.2.1 Definition 7.4.2.2 Quality 7.4.3 Specifications

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7.4.3.1 7.4.3.2 7.4.3.3

7.5.0

7.6.0

Projection, Datum, Coordinate System Scanning of Negative/Diapositive Control Point Configuration 7.4.3.3.1 Without ABGPS and IMU 7.4.3.3.2 With ABGPS and IMU 7.4.3.3.3 Check Points 7.4.3.4 Preparation 7.4.3.4.1 Pass Points 7.4.3.4.2 Tie Points 7.4.3.4.3 Softcopy Point Marking and Transfer 7.4.3.4.4 Coding 7.4.3.5 Mensuration 7.4.3.6 Adjustment 7.4.3.6.1 Preliminary Strip Formation 7.4.3.6.2 Simultaneous Bundle Adjustment 7.4.4 Deliverables Manual and Specifications for Satellite Mapping 7.5.1 Background 7.5.1.1 General 7.5.1.2 Triangulation of Satellite Images 7.5.1.2.1 Camera Model 7.5.1.2.2 Coordinate System 7.5.1.3 Triangulation of Single Image 7.5.1.4 Triangulation of Block of Satellite Imagery 7.5.1.5 Multisensor Triangulation 7.5.2 Specifications 7.5.2.1 Data Characteristics 7.5.2.2 Projection, Datum, Coordinate System 7.5.2.3 Product Levels 7.5.2.4 Image Acquisition Order Polygon 7.5.2.5 Cloud Cover 7.5.2.6 Sun Angle 7.5.2.7 Imagery Options 7.5.2.8 File Format 7.5.2.9 Bits/Pixel 7.5.2.10 Resampling 7.5.2.11 Support Data 7.5.2.12 Mosaic 7.5.2.13 Block Adjustment 7.5.3 Deliverables Specifications for the Compilation of Digital Image Mapping 7.6.1 General 7.6.1.1 Digital Orthoimagery 7.6.1.1.1 Definition 7.6.1.1.2 Quality 7.6.2 Specifications 7.6.2.1 Projection, Datum, Coordinate System 7.6.2.2 Project Extent 7.6.2.3 Ground Sampling Distance (GSD) 7.6.2.4 Data Conversion 7.6.2.4.1 Scanning if Analog Aerial Photography 7.6.2.4.2 Digital Photography or Satellite Imagery 7.6.2.5 Processing Algorithms 7.6.2.5.1 Rectification 7.6.2.5.2 Resampling 7.6.2.6 Accuracy 7.6.2.6.1 Scanner Accuracy 7.6.2.6.2 DEM Accuracy

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Qatar Survey Manual – Table of Contents

7.7.0

7.8.0

7.9.0

7.6.2.6.3 Pixel Size and Selection 7.6.2.6.4 Summary of Errors 7.6.2.7 Photo Selection 7.6.2.8 True Ortho 7.6.2.9 Mosaicing 7.6.2.10 Radiometry 7.6.2.11 Data Format 7.6.2.12 Quality Control 7.6.2.12.1 Reports 7.6.2.12.1.1 Production Flow 7.6.2.12.1.2 Fiducials 7.6.2.12.1.3 Space Resection 7.6.2.12.1.4 Rectification Quality (Spatial) 7.6.3 Deliverables Specifications for the Compilation of Digital Geospatial Data 7.7.1 General 7.7.1.1 Digital (Vector) Geospatial Data 7.7.1.1.1 Definition 7.7.1.1.2 Quality 7.7.2 Specifications 7.7.2.1 Projection, Datum, Coordinate System 7.7.2.2 Project Extent 7.7.2.3 Accuracy 7.7.2.3.1 Coordinate Resolution 7.7.2.4 Data Model 7.7.2.4.1 Compilation Rules 7.7.2.4.2 Control Points 7.7.2.4.3 Hard Copy 7.7.2.5 Deliveries and Production Process 7.7.2.5.1 Production Process 7.7.2.5.1.1 Photogrammetric Compilation 7.7.2.5.1.2 Site Verification 7.7.2.5.1.3 Final Edit 7.7.2.5.1.4 CGIS Quality Assurance 7.7.2.5.2 Materials to be Delivered 7.7.2.5.3 Quality Control 7.7.2.5.3.1 Reports 7.7.2.5.3.2 Production Flow 7.7.2.5.3.3 Stereo Model Set-up Sheets Specifications for the Compilation of Digital Elevation Models 7.8.1 General 7.8.1.1 Digital Elevation Models 7.8.1.1.1 Definition 7.8.1.1.2 Quality 7.8.2 Specifications 7.8.2.1 Projection, Datum, Coordinate System 7.8.2.2 Project Extent 7.8.2.3 Accuracy 7.8.2.4 Compilation Rules 7.8.2.4.1 Feature Digitizing Rules 7.8.2.4.1.1 Transportation Breaklines 7.8.2.4.1.2 Physical Breaklines 7.8.2.4.1.3 Hydrographic Breaklines 7.8.2.4.1.4 Building Heights 7.8.2.5 Quality Control 7.8.2.6 DEM Report 7.8.3 Deliverables Specifications for 3D City Model Mapping

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7.9.1

7.9.2

7.9.3 References

General 7.9.1.1 3D City Models 7.9.1.1.1 Compilation Specifications 7.9.2.1 Projection, Datum, Coordinate System 7.9.2.2 Project Extent 7.9.2.3 Accuracy 7.9.2.4 Vertical Aerial Photography 7.9.2.5 Oblique Aerial or Terrestrial Photography 7.9.2.5.1 Multi-Cameras Oblique Aerial Photography System 7.9.2.6 Quality Control 7.9.2.7 3D City Model Reports Deliverables

298 298 299 299 299 299 299 300 300 300 300 301 301 302

Chapter 8 – Geographic Information System Abbreviations 8.1.0 State of Qatar Geographic Information System (GIS) 8.2.0 Management of GIS 8.2.1 Strategic Management 8.2.2 Tactical Management 8.2.3 Operation Management 8.2.4 Executive Management 8.2.5 Functional Users Management 8.3.0 Structural Framework for the Development of Geographic Information Systems 8.3.1 Initiation 8.3.2 Evaluation 8.3.3 Preliminary System Design 8.3.4 Implementation Management 8.3.5 Maintenance 8.3.6 Feedback 8.4.0 Geospatial Data Overview and Standards 8.4.1 Geospatial Data Components 8.4.2 Geospatial Data Standards 8.5.0 Geospatial Database Specification 8.5.1 Vector Data Equivalence 8.5.2 Tabular Data Model 8.5.3 Qatar National GIS Data Dictionary Specifications 8.5.4 Accuracy of GIS Database References Appendix 8A – Eligible GIS Member Agencies

303 304 305 305 306 307 307 310 310 311 312 313 314 317 318 318 318 319 319 320 323 323 338 341 342

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Qatar Survey Manual - Preface

1.1

Introduction

The objective of this Qatar Survey Manual is to provide up-to-date standards and specifications for various types of survey and mapping activities in Qatar. It will also be based on generally accepted principles and practices of surveying. The Manual is also to serve as the basis for all survey and mapping activities in Qatar in the foreseeable future. Hence, all surveys conducted in accordance to the standards and specifications as laid out in this Manual will be assured of the same level of consistency and accuracy. This will ensure the reliability of all the survey data and enhance the confidence level of all its users. With this standardized survey data, it can be uploaded onto the Qatar GIS system as seamlessly as possible. To achieve the above objectives, a series of meetings and discussions, between Surbana and representatives from UPDA and various agencies, were held. The purpose of these meetings/discussions is to have an in depth understanding of the current practices and the needs of the users. With the above users’ needs and expectations in mind, • • • •

researches were conducted through internet, other academics were consulted, attended seminars and conferences on various surveying disciplines, and studies of the most relevant reports and books

to derive these best practices in various types of survey for Qatar. 1.2

Purpose

The Standards and Specifications in this Qatar Survey Manual will enable users: •

• • • • • • •

1.3

to understand the survey datum adopted of the State of Qatar and to adopt modern survey instrumentation and techniques to establish appropriate survey control network of international standard to understand the governance, administrative authority and procedure of conducting cadastral survey within the State of Qatar in completing a topographic survey from the field to the plan which supports the input to CGIS database in deciding which standard to adopt in order to achieve the accuracy that is needed for different requirements in hydrographic survey in achieving a good practice standard to ensure proper setting out for construction works to appreciate the background to, and the various techniques for, the determination of the gravity data required for precise geoid computations to understand the practices for Digital Mapping photogrammetrically derived or compiled from aerial photograph and/or satellite imagery to appreciate the management and framework for the development and maintenance of GIS in State of Qatar Scope

This Manual covers the standards and specifications for the following types of survey: i.

Chapter 1 – Control Survey This chapter covers the establishment of horizontal and vertical control networks for landbased surveying techniques.

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Qatar Survey Manual - Preface

ii.

Chapter 2 – Cadastral Survey This chapter covers cadastral survey of land parcels and strata units within the State of Qatar. It serves to provide the procedures, practices and a technical guide relating to the conduct of cadastral surveys in the State of Qatar. It does not list details of established practices which accredited surveyors are fully aware of and have been practicing them.

iii.

Chapter 3 – Topographic Survey This chapter covers the execution of topographic surveys using Total Stations, GNSS and 3D Terrestrial Laser Scanner.

iv.

Chapter 4 – Hydrographic Survey This chapter states the level of competence of hydrographic surveyors permitted to conduct hydrographic surveys in Qatari waters, the orders of accuracy and purposes of the hydrographic surveys.

v.

Chapter 5 – Construction Survey This chapter covers both the work procedures and practices governing horizontal and vertical setting out survey for various infrastructural construction work.

vi.

Chapter 6 – Gravimetric Survey This chapter concentrates upon the specifications required for gravity surveys conducted specifically for geoid computation and not intended, or applicable, for gravity surveys conducted for geophysical exploration.

vii.

Chapter 7 – Digital Mapping This chapter covers the specifications and practices for Aerial Photography, Aerial Triangulation, Digital Image Mapping, Satellite Image Mapping, Digital Vector Mapping, Digital Elevation Model and 3D Model, to be used in support of the production of Digital Orthoimagery, Vector, DEM, 3D City Model or Photogrammetrically compiled products of National Mapping Project for CGIS.

viii.

Chapter 8 – Geographic Information System This chapter concentrates on the management and initiation, evaluation, preliminary system design, implementation management, maintenance and feedback for the development of GIS. It also covers the geospatial data overview and database specifications.

1.4

Acronyms, Definitions and Abbreviations

Below is a list of acronyms, definitions and abbreviations used throughout this Preface of this Manual: i. ii. iii. iv. v. vi.

3D – 3 Dimension CGIS – Center for Geographic Information System, Qatar DEM – Digital Elevation Model GIS – Geographic Information System GNSS – Global Navigation Satellite System GSD – General Survey Department 2

Qatar Survey Manual - Preface

vii. viii. 1.5

Manual – Qatar Survey Manual UPDA – Urban Planning and Development Authority, Qatar Acknowledgement

We would like to take this opportunity to thank the Qatar Survey Manual Technical Evaluation Group: i. ii. iii. iv. v. vi. vii. viii. ix.

Manaf Ahmed Al Sada, CGIS Director Ali Mohd. Al Majid (CGIS) – Chairman Eufrepes E. Pangapalan, Jr. (CGIS) – Member K. D. Ranjith Wijekoon (CGIS) – Member I.M. Dayarathna (CGIS) – Member Mohammed Abd-Elwahab Hamouda (CGIS) – Member Vladan Jankovic (GSD) – Member Joalvin C. Villaroman (GSD) – Member Restituto P. Villareal (GSD) – Member

and also other representatives from: i. ii. iii. iv. v. vi. vii.

Topographic Survey Division – CGIS, UPDA General Survey Department – UPDA Hydrographic Section – GSD, UPDA Mapping & Archives Services Division – CGIS, UPDA Planning & Projects Division – CGIS, UPDA Planning Department – UPDA various agencies like Ministry of Interior, Ministry of Minicipal Affairs & Agriculture, Qatar Petroleum, Public Works Authority and others

for their support, cooperation, patience, and most of all, guidance provided.

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Qatar Survey Manual – Chapter 1 – Control Survey

Abbreviations CGIS

Centre for Geographic Information System

CORS

Continuously Operating Reference Stations

CRS

Coordinate Reference System

DGNSS

Differential Global Navigation Satellite System

E

Easting

EDM

Electronic Distance Meter

FBM

Fundamental Bench Mark

GDOP

Geometric Dilution of Precision

GNSS

Global Navigation Satellite System

GPS

Global Positioning System

H

Ellipsoidal Height

IGS

International GNSS Service

ITRF

International Terrestrial Reference Framework

L or λ

Geographic Longitude

n

Geoid Height

N

Northing

NGS

National Geodetic Survey (US)

O

Orthometric Height

P or Φ

Geographic Latitude

QND

Qatar National Datum

QND95

Qatar National Datum 1995

QNG

Qatar National Grid

RINEX

Receiver Independent Exchange format

RTK

Real-Time Kinematic

UTM

Universal Transverse Mercator

WGS84

World Geodetic System 1984

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Qatar Survey Manual – Chapter 1 – Control Survey

1.1.0

Datum

Geometric spatial reference data (3D position, position and height) must be presented in standardized, geodetic spatial reference systems, the so-called coordinate reference system. According to the EN ISO 19111:2007 standard (Spatial Referencing by Coordinates), a coordinate reference system (CRS) consists of two components, the “datum” and the “coordinate system”. The datum, often also designated as the reference system, is the physical part of a CRS which establishes the reference to the Earth by definition of the zero point, the orientation of the coordinate axes and the scale. A datum can be a geodetic datum, a vertical datum or an engineering or local datum: The coordinate system is the mathematical part of a CRS which establishes how coordinates are assigned to a geometry, e.g. a fixed point, using rules. The coordinates of a geometry can be stated, e.g. as Cartesian coordinates (X, Y, Z), ellipsoid coordinates (width, length and, where applicable, ellipsoidal height) or projected coordinates (Qatar National Grid, Gauß-Krüger mapping, UTM mapping, etc). As well as the CRS for 2D and 3D position data, some coordinate reference systems are defined for managing height data or coordinates (e.g. mean sea level heights). Transformations are necessary for the transfer of coordinates of a datum or reference system to another datum. Underlying any coordinate used for Surveying & Mapping, or indeed any positional information, is a Geodetic Datum. It is imperative that the datum is well defined and reproducible so that any positioning activity may be related to it. Geodetic Datum - Prime Meridian Most geodetic datums use Greenwich as their prime meridian. Default values for the attributes prime meridian name and Greenwich Longitude shall be “Greenwich” and 0 degree, respectively. Geodetic Datum – Ellipsoid An ellipsoid specification shall be provided if the datum is geodetic. An ellipsoid shall be defined either by its semi-major axis and inverse flattening, or by its semi-major axis and semi-minor axis, or as being a sphere. Geodetic datum’s in use in the State of Qatar are World Geodetic System 1984 (WGS84) and Qatar National Datum 1995 (QND95). QND95 is the datum used for surveying, mapping and related activities while WGS84 is the datum realized through the use of surveying techniques involving the Global Navigation Satellite System (GNSS). Coordinates derived through the use of GNSS are immediately transformed to QND95 except in a few circumstances such as the Civil Aviation Authorities who use WGS84 to maintain compatibility with their world-wide counterparts. Similar to most jurisdictions, the State of Qatar uses a map projection of the reference ellipsoid so that users may use grid {N, E} coordinates rather than the more complex geodetic coordinates { φ, λ, H }. Two projections are used in Qatar; Qatar National Grid (QNG) and Universal Transverse Mercator (UTM). QNG is encouraged throughout the State and is the only projection supported on QND95. UTM is available on the WGS84 datum only. 1.1.1

Reference Ellipsoids

The parameters of the reference ellipsoid for the World Geodetic System 1984 (WGS84) are: Semi - major axis (a) Flattening (f)

= =

6,378,137.0 m 1 / 298.257223563

Qatar National Datum 1995 (QND95) uses the International (Hayford) reference ellipsoid whose parameters are: Semi - major axis (a) = 6,378,388.0 m Flattening (f) = 1 / 297.00

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Qatar Survey Manual – Chapter 1 – Control Survey

1.1.2

Geodetic Datum

The two geodetic datums, WGS84 and QND95 are defined: WGS84 WGS84 used in Qatar is defined by the United States Defense Mapping Agency in their document “Department of Defense World Geodetic System 1984 - Its Definition and Relationship with Local Geodetic Systems”, DMA TR 8350.2, dated September 30 1987 [Second Printing]. QND95 QND95 is defined by transforming WGS84 coordinates using a 7-parameter coordinate transformation,

X  X  ∆X   ∆s Y     ∆Y  + − r = + Y        z  Z  QND 95  Z  WGS 84  ∆Z   ry

rz ∆s − rx

− ry   X   rx   Y  ∆s   Z  WGS 84

where the 7 parameters are: X - translation Y - translation Z - translation X - rotation Y - rotation Z - rotation

= = = = = =

∆X = +119.42480 m ∆Y = +303.65872 m ∆Z = +11.00061 m

rx ry rz

Scale change

=

∆s = -3.657065 ppm

= - 1.164298” = - 0.174458” = - 1.096259”

} The – sign must change to + sign for the } 3 rotations in some software, considering } its direction of rotation.

The 7 parameters, { ∆X ∆Y ∆Z rx ry rz ∆s } are exact values, that is, QND95 is defined by taking a WGS84 coordinate and applying the above transformation. The Qatar95 geoid model is incorporated into the transformation parameters. To obtain geodetically correct transformed coordinate values, the geoid model must be used. In some instances an approximate transformation using only 3 parameters may be used,

X  X  ∆X  Y  = Y  +  ∆Y         Z  QND 95  Z WGS 84  ∆Z  where the 3 parameters are: X - translation = Y - translation = Z - translation =

∆X ∆Y ∆Z

= +127.78098 m = +283.37477 m = -21.24081 m

See Appendix 1A for sample transformation calculation.

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1.1.3

Vertical Control Datum

The Qatar Vertical Datum is defined as the Mean Sea Level 1970-1972 being 8.0036 meters below the Fundamental Bench Mark B (FBMB, Private Mark) located at the north end of the runway at Doha International Airport. 1.1.4

Map Projection

Qatar National Grid (QNG) QNG is a transverse Mercator map projection using the following values: Northing origin Easting origin False Northing False Easting 1 Scale factor at origin

N 24° 27’ 00” E 51° 13’ 00” 300,000.0 m 200,000.0 m 0.99999(exact)

Universal Transverse Mercator (UTM) The UTM map projection used in Qatar is the standard definition of UTM. It is only used on the WGS84 datum and not QND95. All UTM values in Qatar fall in zone 39 (Central Meridian 51° East Longitude). 1.1.5

Geoid Model – Qatar95

In order to relate the ellipsoidal height derived from GNSS surveys to the desired orthometric height (sea level height) a geoid model is required. The State of Qatar has defined its own geoid model, Qatar95. It was derived by using the OSU91a geoid model and supplementing it with “known” geoid ellipsoid separations at 71 primary geodetic stations. For users in the State of Qatar, program QTRANS is available from the Centre for GIS that computes both coordinate transformations between WGS84 and QND95 and also the Qatar95 geoid components (Geoid Ellipsoid separation, and deflections of the vertical).

1

QNG is defined in terms of the scale factor at the origin (central meridian) not the zone width.

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Figure 1.1: Geoid Model of Qatar (Qatar95) 9

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1.2.0

Standards

1.2.1

Introduction

This section defines the fundamental requirement for a set of technical standards and specifications for horizontal and vertical control. These standards and specifications must always directly relate to the national coordinate reference systems and to the control of geodetic, engineering, mapping, cadastral surveys and spatial elements of geographic information systems. 1.2.2

Order – Horizontal Control

Stations in horizontal control surveys are assigned an ORDER commensurate with the precision of the survey and the conformity of the survey data with the existing coordinate set. The ORDER assigned to the stations in a new survey network following constraint of that network to the existing coordinate set may be; not higher than the ORDER of existing stations constraining that network. The allocation of ORDER to a station in a network, on the basis of the fit of that network to the existing coordinate set, may generally be achieved by assessing whether the semi-major axis of each relative standard error ellipse or ellipsoid, with respect to other stations in the fully constrained network, is less than or equal to the length of the maximum allowable semi-major axis. This technique makes use of the formula adopted from “Standards and Practices for Control Surveys Special Publication 1 (SP1) V1.6” published by The Intergovernmental Committee on Surveying and Mapping (ICSM), Australia: 1

r = c ( d + 0.2 ) Where r c

= =

d

=

length of the maximum allowable semi-major axis in mm. an empirically derived factor represented by historically accepted precision for a particular standard of survey. distance between two stations in km.

The values of “c” for various ORDERs of survey are shown in Table 1.1(a) which is taken from SP1 V1.6. Table 1.1(a): ORDER of Horizontal Control Survey

1

ORDER

c value (for one sigma )

0 1 2 3 4

3 7.5 15 30 50

Experience has shown that with most modern methods of establishing closely spaced control, the overall pattern of error propagation is not proportional to distance but rather to: the combination of instrumental and centring errors, the effects of network configuration and a host of other contributing errors - most of which defy individual identification. The errors of measurement contributing to this pattern can be divided into two groups: (a) those proportional to distance which are dominant on lines longer than one kilometre; and (b) those non-proportional to distance which are dominant on lines shorter than one kilometre. The adoption constant “0.2” as one element of the formula in the determination of ORDER will generally provide these specifications with the flexibility necessary to accommodate survey networks containing control stations which are closely spaced, widely spaced or with variable spacing.

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A survey network is adjusted in a constrained least squares process which satisfies the a posteriori statistical tests. In the adjustment output, standard (1 σ) line error ellipses (relative ellipses) are generated from each point to adjacent points in the network. The allowable limit, for instance of 1st Order position, is calculated for each of these lines and compared to the ellipse’s semi-major axis. If all the line error ellipses from a point are less than or equal to their limit for 1st Order, and the constrained points in the least squares adjustment are 1st Order or better, then hypothesis is true and the position may be adopted as 1st Order. If line ellipses from a point are greater than the limit for 1st Order, or the constraint stations in the least squares adjustment are less than 1st Order, the hypothesis is false and the position should be tested for a lower Order. Example: The line error ellipses and distances from point 1 to points 2, 3 & 4 are as shown:

From

To

Semi-major axis

Distance

1st Order allowable limit

1

2

0.23 m

33 km

7.5(33+0.2) = 0.248 m

1

3

0.16 m

27 km

7.5(27+0.2) = 0.204 m

1

4

0.30 m

42 km

7.5(42+0.2) = 0.316 m

As the semi-major axes of the line error ellipses from Point 1 to Points 2,3 & 4 are all less than their respective 1st Order limit, provided all constraint stations in the constrained least squares adjustment are 1st Order or better, Point 1 may be classified as 1st Order. With ORDER, it is recognized that assessment of the quality of a network following a constrained adjustment remains dependent upon a subjective analysis of the adjustment, the survey, and the ties to the existing coordinate system. The ultimate responsibility for the assignment of ORDER to the stations in a survey network must remain within the subjective judgment of the geodesists of the relevant authority. As a 1 comparison, Table 1.1(b) depicts the conventional order of horizontal control survey based on relative distance accuracy. 1

Table 1.1(b): Conventional ORDER of Horizontal Control Survey in the State of Qatar

1.2.3

Order

Classification (Relative Distance Accuracy)

Equivalent ppm

0 1 2 3 4

1:1,000,000 1:100,000 1:50,000 1:25,000 1:10,000

1 ppm 10 ppm 20 ppm 40 ppm 100 ppm

Order – Vertical Control

The assignment of an ORDER is largely technique dependent. ORDER assigned to the height of a mark following a constrained adjustment will be commensurate with: • 1

the order of the constraining heights,

All horizontal control coordinates values should be shown up to 3rd decimal of meter

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the precision of the transformation from one height datum to another, the magnitude of the discrepancy between the newly heighted and existing height differences of the survey marks at the abuttal of the new and existing leveling routes/vertical networks, and for GNSS heighting, the accuracy of the geoid-ellipsoid separation.

• • •

ORDER of height of a mark from a survey is allocated on the basis of the fit of that survey to existing (constraining) heights. This technique makes use of the formulae adopted from (SP1) V1.6 published by The Intergovernmental Committee on Surveying and Mapping (ICSM), Australia. The formulae are shown in Table 1.2(a) for the different surveys: Table 1.2 (a): Values of c for Various ORDERS of Heights Differential leveling r = c√ d ORDER 0 1 2 3 4

1

Trigonometric and GNSS heighting r = c(d+0.2) c (for 1 σ) 2 4 8 12 18

ORDER 3 4

2

c (for 1 σ) 30 50

Where: r = maximum allowable error, in mm. c = an empirically derived factor for each particular ORDER of survey result. d = distance between two stations in km Example: Consider a closed spirit-leveling network with a closure of 0.007 m, around a 15 km long loop. The standard deviation of each of the heights assigned to the 5 newly established Benchmarks, after a minimally constrained network adjustment, is approximately 0.001m. 3

Despite the closure rate and height values of better than ORDER 1, the equipment and procedures used requires that ORDER 3 or lower be assigned to the network. The survey is connected to one ORDER 1, two ORDER 2 and three ORDER 3 existing Marks. Though the constrained adjustment of the leveling loop achieved better than ORDER 1 agreement with the existing control, the highest ORDER to be allocated for the survey is ORDER 3 With ORDER, it is recognized that assessment of the quality of heights following a constrained adjustment remains dependent on a subjective analysis of the adjustment, the survey, and ties to the existing height system. The ultimate responsibility for the assignment of ORDER to the heights in a survey network must remain within the subjective judgment of the Authority or personnel in charge of the survey or of the vertical adjustment. Table 1.2 (b) depicts the conventional criteria used in the State of Qatar for the order of vertical control survey based on elevation closure. It could be used for comparison.

1 2

3

For differential leveling - the standard deviation of each height observation is less than or equal to the maximum allowable value (r). For GNSS and trigonometric heighting - the standard deviation of each height observation is less than or equal to the maximum allowable value (r). See Table 1.5 in Section 1.2.5.3

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Table 1.2 (b): Conventional ORDER of Vertical Control Survey in the State of Qatar

Order

Classification – Elevation Closure (mm)

0 1 2 3 4

1.5 √K 1 1.5 √K 1 3 √K 1 12 √K 1 24 √K

1

1.2.4

Instructions and Guidelines for Control Surveys

1.2.4.1

Control Survey

For maintaining accuracy levels, internal consistency of the Horizontal & Vertical control networks and CGIS data backup procedures, following guidelines to be followed in executing control surveys. (A)

Horizontal Network (Using Spatial Technique) (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x) (xi) (xii)

(B)

Fixed or Reference stations must be in a higher order than the intended horizontal order of the new stations. Fixed or Reference stations to be selected to equally distribute in all quadrants. Observation schemes and observation log sheets to be properly maintained. Sufficient baselines between fixed or reference stations to be observed in an equally distributed manner. At least three fixed/reference stations to be connected in every network. Including perimeter baselines, at least three baselines with every new station to be observed with other new stations when network has more than four stations. Few baselines to be observed connecting new stations lying at the extreme locations of the perimeter in the network when possible (more than 5 stations) for good strength of the network. When Spatial Technique (GNSS) is used, STS (Static) and RSTS (Rapid static) modes are accepted. A minimum observation time is ten (10) min. for dual frequency receivers and can go up depending on the length of the base line. For better network adjustment at least three GNSS receivers to be occupied for one session observations simultaneously. Least-squares adjustment to be done for network constraint adjustment. For checking internal consistency with existing control stations, few baselines to inter-visible or nearby stations to be observed. However, these baselines should not be included in the final adjustment & computations. rd Final coordinates values must be given in QNG coordinates (QND95 Datum) showing to 3 nd decimal. GNSS heights must be showing to 2 decimal. For getting correct GNSS height values, QATAR95 Geoid model to be applied in the computations.

Vertical Network (i)

Fixed or Reference stations must be in a higher order than the intended vertical order of the new stations. (ii) For Second or Higher, order leveling must be done both ways (up and down) with standard th manner. Final height values must be showing to 4 decimal. nd (iii) Least-squares adjustment must be done for level network adjustment (specially 2 Order and above) (iv) Field records and level line route diagrams to be maintained properly and attached to the final report. 1

√K = square root of distance in kilometres

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(v) GNSS heights are always in 5 order classification. Values showing up to 2

nd

decimal.

1.2.4.2 Control Survey Returns (A)

Complete Survey Report (Hard copy)

Separate sections for Horizontal network and Vertical network in same report or two different reports will be acceptable. These reports should contain following sections: (i) (ii)

(iii) (iv) (v) (vi) (B)

Digital Data (i) (ii) (iii) (iv) (v) (vi)

1.2.4.3

Front Cover – displaying Project name and other information Project summary file in MS word, MS excel or Plain text format. It should include the following details which are used to update tables and control database, • Project reference number or numbers • Area name • Period of Survey (Start date and End date) • Instrument used for Observation (with brand, model and serial numbers) • Observation method or scheme briefly • Names of Survey Software used for computation and adjustments • Reference/Fixed station details (Name, Northing, Easting, Height, H_order, V_order, Monu_type, Fixed status) • New stations coordinates (Name, Northing, Easting, Height, Monu_type, Remarks) Computation Files - Adjustment & Computation List files, Computation summary files, Log files, Original manual data entry forms, GNSS log sheets, Diagrams generated from computation software ….. etc. Field Notes – GNSS Log sheets, Original manual data entry forms ….etc References – Field Diagrams, Fixed stations data…etc Description sheets for new monuments

GNSS Raw data - Leica system 1200 raw data is accepted. For other brand GNSS receivers, RINEX format digital raw data is a must. Digital level Data – Field raw data & Edit data. Computation & adjustment listing files, summary files and output files. Survey report Project summary file in MS word, MS excel or Plain text format. Digital copies of other files included in Survey report. Digital copies of Survey stations' description sheets. Digital Data Structure (To be Used for CGIS Data Backing Up Requirements) 1

Following Directory structure is to be followed. All data files are to be in unlocked mode. 1. Level 1 2. Level 2 2

3. Level 3

1 2

qarsxx yymm

xx indicate more stations included qars number. eg: 0901 - "09" indicate year, "01" indicate month of observation started. (i) doc Digital copies of all attached documents to the report. (ii) rawdata/ssssss/yydddx where, ssssss – station name yyddda – yy (year) ddd (gpsday) a (session/occupation) st e.g. rawdata/560036/08366a (observed on 31-Dec-2008, 1 occupation) nd rawdata/560036/08366b (observed on 31-Dec-2008, 2 occupation)

Directory structure levels 1-3 are a must. Appropriate sub directories under the level 3 depend on the requirements of the control project.

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(iii) Adjustment (iv) leveling/rawdata /editdata /adjustment (v) descriptions

-

Network adjustment files digital raw data from filed data edit data for leveling digital files for leveling adjustment digital copies of new station description sheets in MS Excel format

Sample Directory Structure as follows

1.2.5

Specifications for Surveys and Reductions

Control networks are produced by making suitably accurate measurements and referring them to identifiable adjacent control points in the existing network. The combination of survey design, instrumentation, calibration procedures, observation techniques and data reduction methods comprise a control survey system. The required ORDER of fit to the control points of the proposed survey will determine the field methods and reduction techniques to be employed to achieve them. The purpose of this section is to provide the surveyor with a guide to the minimally acceptable practices which apply to the equipment, and to the appropriate reduction methods to meet the standards of a particular ORDER of survey. Adherence to the Recommended Practices described in this section is NOT mandatory in order to achieve a given ORDER. However, if not used, the onus is on the user to prove that the practices used will achieve the desired level of precision. Survey Techniques Each of the following sections deals with a specific surveying technique. The sections are not designed to be used as a text book and may not contain comprehensive lists of techniques and procedures. It is assumed the user of this document has a basic understanding of the techniques being used. If not, a suitable reference text should be consulted.

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1.2.5.1

Electronic Distance Measurement - EDM Table 1.3 (a): EDM Observation Requirements

ORDER Number of days of observations Number of sets of 1 full measurements 2 Move prisms between sets 3 Range of fine readings 3 Difference between two sets Difference between means of 3 each day's measurements Observation between 2 hours before local noon, and 2 hours 4 before local sunset Atmospheric dial setting (where possible) 5 Allow minimum warm up time Thermometer type

1

2

3

4

2

1

1

1

1

4

4

2

1

1

Yes 0) 9-19 (decimals >0)

Float Double Float Double

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Table 8.5: Geometry Type Mapping between CAD and Geodatabase: CAD feature class Point Polyline Polygon

Geodatabase geometry Point Line (polyline) with Zs Polygon with Zs

Table 8.6: Field Mapping between CAD Field and Geodatabase: Filed type String Integer Double

Geodatabase field type Text Long integer Double

Table 8.7: Legacy Data and Geodatabase Equivalents Coverage

1

Geodatabase

Description

Workspace Coverage Feature class Tic

Geodatabase Feature dataset Feature class N/A

RDBMS that contains data Contains topologically related feature classes Contains feature of same geometry GDB does not use; may import as points

Bnd Arc Node Point Polygon Polygon Label Route

N/A Line Point Point Polygon N/A Line

Extent is a property of the spatial reference Line may be multipart, like routers GDB does not use; may import as points Points may be multipart Polygons are "simple", not chains of arcs GDB does not use; may import as points Lines with m (measure) coordinates

Region Annotation N/A Network Topology

Polygon 1 Annotation

Polygons may be multipart, like regions Feature linked or not A type of graphical annotation Topologically related lines and points A set of rules defining spatial relationships

Dimension Network Topology

Annotation in the geo-database is not a geometry type but is implemented as a feature type.

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8.5.2

Tabular Data Model

The use of tabular data model depends on the Database Management System (DBMS) in which the table is stored such as Oracle®. The geodatabase supports only the following seven generic field data types, data types not in the table cannot be used: Data Type

Bytes

Short integer Long integer Float

2 4 4

Double Text Date BLOB

8 Varies 8 Varies

Range/format/notes -32,768 to +32,767 -2,147,483,648 to +2,147,483,648 About -3.4e38 to +1.2e38(~7 significant digits) About -2.2e308 to +1.8e308(~14 significant digits) Up to ~64,000 characters mm/dd/yyyy hh:mm:ss am/pm Store images or other multimedia

Oracle® ®

Data types used in Oracle are as follows: CHAR

Character

VARCHAR2

Character

NUMBER

Number

DATE

Date

LONG

Long Text

RAW

Raw Binary Large Object (BLOB) BLOB

LONGRAW BLOB

8.5.3

A fixed-length character string up to 2000 bytes in length. It will pad unused bytes with spaces. A variable-length character string up to 4000 bytes. It will not consume storage space for unused bytes. A variable-length number field, either with or without decimals. There is a maximum of 38 significant digits. A fixed length, 7-byte field, includes both calendar date and time of day. A variable length character string of up to 2GB (231 bytes). A variable-length binary data, only 2000 bytes. A variable-length field used for binary data up to 2GB (231 bytes). Binary large object, up to 4 GB in length

Qatar National GIS Data Dictionary Specifications

These specifications are administered under the authority of the National Geographic Information Systems (GIS) Steering Committee. It is the responsibility of this committee to provide national standards and specifications for all GIS databases in the State of Qatar that are compatible, and provide for effective sharing/exchange of data where such sharing is warranted. The Qatar National Geographic Information Systems Database Specifications & Data Dictionary is a multi-volume set of “Information Resource Catalogues”.

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Each GIS Data Dictionary is one volume in a series, of which focuses on a particular resource. The full series includes the following: Table 8.8: GIS Data Dictionaries Volume 1

Topographic

Volume 6

Water

Volume 11

Real Estate

Volume 2

Volume 7

Police Services

Volume 12

Environment

Volume 8

Agricultural Services

Volume 13

Fisheries

Volume 4

Drainage - PWA Urban & Regional Planning and Development Roads - PWA

Volume 9

Telecommunications

Volume 14

Education

Volume 5

Electricity

Volume 10

National Statistics

Volume 15

Health

Volume 3

Geodatabase is a container of geographic data objects and often refers to as workspace. The various types of objects it contains such as Tables, Feature classes, Subtypes, Feature datasets, Raster datasets, Relationship classes, Geometric networks, Topologies, and rules. Geodatabase addresses both geographic and non-geographic data issues. They are organized as follows: Table 8.9: Organization of Geodatabse Components Data Model Feature Datasets

List of all required data models Description of all required Feature Datasets and listing of Feature Classes, Topology layers, Geometric Network, Annotation FC, Dimensions (geographic object classes), and features' hierarchy

Feature Classes

Description of all required features classes

Annotation Classes

Description of all required annotation classes

Topology

Description of all required topologies

Domains/Subtypes

Description of required domains and subtypes

Tables/Object Classes

Entities (non-geographic object classes) and their attributes, if applicable

Relationship Classes

Description of relationship classes, if applicable

Geometric Networks

Description of all required Geometric Networks

Network Datasets

List all required Network Datasets

Raster Dataset

Description of all raster datasets; if applicable

Raster Catalogs

Description of all raster catalogs; if applicable

Others

Indexes/Other Object Classes, optional

Features

Description of features (geographic object classes)

(a)

Data Model

Data modeling plays an important role in all software environments. Data models can be used as simple representations of reality. The focus of most geographic information systems (GIS) is on the spatial relationships between entities in the real world. Having an accurate and structured dataset is crucial to the validity of the complex spatial analysis that is to be performed by a GIS. In order to maintain the integrity of data imported and edited by the end user, strict controls must be imposed via the model. Place all schematics of Object Oriented data models created either using CASE and UML for designing and building a geo-database e.g. Visio or any latest tool available/supported by ESRI technology to specify UML model.

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(b)

Feature Datasets

The purpose of this section is to identify all feature datasets, topology layers, geometric network and geographic object classes including Annotation and Dimension object classes required for each datasets. These should be listed alphabetically by the classes name in respective Feature Dataset. Feature Datasets is a collection of feature classes that shares the same spatial reference. To model or maintain spatial relationships in feature classes using a topology or geometric network, the feature classes must reside in a feature dataset. Feature classes that store simple features (not part of a topology or network) can be organized either inside or outside a feature dataset.


Feature class stores features with the same type of geometry and the same attributes. In geo-database, an object class that stores features and has a field of type geometry. For naming convention, please refer to Feature Class section.




Topology: Identification of the spatial relationships that meet the needs between features in one or more feature classes or subtypes that meet the needs of data model. The following types of rules are available:




Point rules Line rules Polygon rules

Separate one or more pages should be devoted to list the names of feature datasets, feature classes, and topology layers or any object classes those are participating in the geo-database. Following illustrates a list of feature datasets, feature classes, and topology layers for topographic database. For example: List of Feature Datasets, Feature Classes and Topology Layers 1. Landscap • • •

Landscap_Arc Landscap_Polygon Landscap_Topology

• • •

Landuse_Arc Landuse_Polygon Landuse_Topology

• • •

Veg_Arc Veg_Polygon Veg_Topology

• • •

Landchng_Arc Landchng_polygon Landchng_Topology

• • •

Urban_Arc Urban_Polygon Urban_Topology

• • •

Trnsport_Arc Trnsport_Polygon Trnsport_Topology

2. Landuse

3. Veg

4. Landchng

5. Urban

6. Trnsport

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7. Landmark •

Landmark_Point

•

Height_Point

8. Height

Topology Rules for Urban Feature Dataset Rule Must Not Overlap Must Not Intersect Must Not Self-Overlap Must Not Have Dangle Must Not Have Pseudo Must Not Intersect Or Touch Interior Must Not Self-Intersect Must Not Overlap Boundary Must Be Covered By

Feature Class

Associated Feature Class

URBAN_ARC URBAN_ARC URBAN_ARC URBAN_ARC URBAN_ARC URBAN_ARC URBAN_ARC URBAN_POLYGON URBAN_POLYGON

URBAN_ARC

The Feature Datasets must be described in alphabetic order by its name. The description of particular feature dataset should be started from separate page. One or more pages should be devoted for each feature dataset. Each page (or group of pages) is of the same format. At the top of the page is the full feature dataset name. This must be unique of any length, but is generally kept of 10 characters. The feature dataset is then described in the following headings: ♦

Description: A long description of the feature dataset's contents in terms of what criterion was used to define it. This will generally be the theme by which compulsory physical relationships were examined.

♦

Name: Write a name of feature dataset which will be used in other naming conventions such as for feature classes, topology layers, etc.

♦

Feature Classes: A list of feature classes that can be found under this feature dataset.

♦

Feature List: A list of features (classes of objects) those can be found in a feature class are 1 listed with each feature name and its Feature GFCODE . The feature list should be further subdivided into separate lists based on the geometric representation of the feature. Each of these lists is sorted in alphabetical order on GFCODE. The geometric representation has been classified into the following categories: ♦ ♦ ♦ ♦ ♦ ♦ ♦




1

Point primitive feature Line primitive feature Polygon primitive feature Line with measure system Point events Linear events Polygon

Known Redundancy: Notes regarding any features in this layer for which their geometry exists redundantly in other layers.

Features and Feature GFCODEs are explained further in the Features – Section 8.5.3 (j).

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Hierarchy: An indication of any topological hierarchy that may exist. For example, polygonal features may be bounded only by those linear features greater than a defined level in a hierarchy of linear features. A similar relationship may also exist between linear and nodal features.




History Notes: If geometric history is maintained, the means by which it's done is identified.




Owner: The agency which owns (or has been appointed as custodian for) the geometry in this layer.




Update Rights: The agencies entitled to submit changes to the geometry in this layer.

The list of features' hierarchy under a respective feature dataset should be started from separate page. One or more pages should be devoted for the same. Write at the top of the page "Feature Hierarchy" then feature data set name and followed by list of all features with their hierarchy. (c)

Feature Classes

The purpose of this section is to identify all feature classes required for each datasets. Here details explain business table of feature class. List and order all the identified feature classes by its name and describe them accordingly. One or more pages are devoted to the description of a feature class. Each page (or group of pages) should have same. At the top of the page is the feature class's full name. The feature class is then described under the following headings:


Name: The entity name, for primary geographic feature tables (business table) of type point, arc, or polygon, the Name assigned must be (_). For example, table landscape_arc would have this Name for arc feature class of landscape feature dataset.




Description: A long description of the feature class.




Feature Dataset: Name of the feature dataset that contains this feature class, if applicable.




RDBMS: The name of the Relational Database Management System within which this business table resides.




Known Redundancy: An indication if there is any data in the table which exists redundantly in other tables.




For the primary geographic feature attribute tables (business tables) in ArcSDE® , a number of mandatory columns exist. Some fulfill GIS software requirements, whereas others fulfill national feature inventory requirements.




Column Data Types: The breakdown of each column in the table should be identified in the following headings such COLUMN (name of the column), TYPE (what kind of value does it accept), WIDTH (how much is the width of column to accommodate the required values) and DECIMALS (number of decimal 2 places) for Oracle® tables, and CHARACTERISTICS to define domain and constraints such as acceptable values, range, validation checks, constraints for further limiting column values, unique key, primary key, foreign key etc. Note that column names can only be of maximum 10 characters in length, and must not conflict with any reserve word identified within ArcSDE® or Oracle® DBMSs. For the primary geographic feature attribute tables (business tables) in ArcSDE®, a number of mandatory columns exist. Some fulfill GIS software requirements, whereas others fulfill national feature inventory requirements.




Column Definitions: A description of what each column represents.

1 2

1

Refer to ArcSDE® documentation for further details Refer Oracle® documentation for further details

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List of Features: Provide a list of all features lie in this feature class in a table format with two columns under heading of GFCODE and definition, for feature details refer Features – Section 8.5.3 (j).




Owner: The agency that owns (or has been appointed as custodian for) the data in this table.




Update Rights on Columns: The agencies which are entitled to submit changes to the data in specific columns of this table.




Relate Table: A table which contains a list of all direct relationships for the given table. In case of many-to-many relates via a link table, both sectors of the relate table are shown on the same row.

Diagram methods: Design documents are often simplified (abstracted) so they may be easily read and understood. Use Unified Modeling Language which is independent of process and language under the Visio environment or any latest visual tools for data and software modeling available at ESRI. ESRI provides Visio templates needed in order to build designed model. They contain ArcObject geodatabase classes, their interfaces, and ESRI extensions to UML. Provide Data Model depicting relationship between feature classes, subtypes for a respective feature dataset. Also list out all domains applied for each feature class/subtype for a feature dataset. For clarity, Link Tables may be omitted. The Lookup Table that does not have its own Appendix C listing must be shown on in the model Master Tables it’s referenced with. A Lookup Table that has its own Appendix C listing must either have its own model, or be shown on the models of Master Tables it’s referenced with. The following class diagrams illustrate the representation of Feature Datasets used for developing topographic model.

LANDSCAPE

LANDUSE

VEGITATION

LANDCHANGE

URBAN

TRANSPORT

HEIGHT

LANDMARK

Figure 8.5: Feature Datasets for Topographic Geo-database

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The following illustration depicts the modeling of Feature Dataset, Feature classes, subtypes, and domains in UML/Visio, showing an example for Urban Feature dataset and its feature classes, subtypes and domains used for modeling topographic database.

URBAN FEATURE DATASET URBAN FEATURE DATASET FEATURE DATASET Generalization

URBAN_POLYGON

URBAN_ARC

+ OBJECTID + GFCODE + TYPE + GFCODE1 + TYPE1 + ARURBN_KY + DATE_LUPD + METHOD + AGENCY + ARURBN_KY1 + SHAPE + SUBTYPECOD

+ OBJECTID + GFCODE + LNURBN_KY FEATURE CLASS + DATE_LUPD + METHOD + AGENCY + SHAPE + SUBTYPECOD

Binary Association

SUBTYPES

Building

Tank

Tower

Pool

+SUBTYPECOD = 14 +GFCODE =TGARBLDG +GFCODE1 +TYPE +TYPE1

+SUBTYPECOD =113 +GFCODE = TGARTANK +GFCODE1 +TYPE +TYPE1

+SUBTYPECOD=129 +GFCODE = TGARTOWR +GFCODE1 +TYPE +TYPE1

+SUBTYPECOD=145 +GFCODE = TGARPOOL +GFCODE1 +TYPE +TYPE1

CODED VALUE DOMAIN Building School Refinery Clinic Light House Mosque Stadium Hospital Police Station Fire Station Government Bank Hotel Souq Co-operative

Tank 001 002 003 004 005 006 008 009 010 011 012 013 014 015

Oil Natural Water Sanitation

Pool

Tower 001 002 003 004

Water

001

Swimming 001 Water Fountain 002

Figure 8.6: Modeling Feature Datasets, Feature Classes, Subtypes, Domain in UML/Visio

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(d)

Topology Layers

Topology: Identification of the spatial relationships that meet the needs between features in one or more feature classes or subtypes that meet the needs of data model. The following types of rules are available:






Point rules Line rules Polygon rules

The primary purpose of geo-database topology is to define spatial relationships between features in one or more feature classes. It stores edited area, rules, errors, and exceptions. The primary spatial relationships to model are adjacency, coincidence, and connectivity. More than one topology rules may be applied in one feature class. Provide a list of all feature classes and/or subtypes affected by topology rules. All topology rules those are going to be applied on feature classes of a feature dataset should be listed under a same feature datasets. List and order all the identified topology layers by its name and describe them accordingly. One or more pages are devoted to the description for each topology layer. Each page (or group of pages) is of the same format. At the top of the page is the full name of topology layer. The topology layer is then described in the following headings: Name: Following naming convention should be followed for topology layers: __Topology Feature Class Name: is the name of feature class whose rank is the highest in the topology relationship. If there is only one feature class in topology then same name should be used. Description: Long description of topology layer's contents in terms of what spatial relationships is maintained and why. Cluster Tolerance: Define a distance in which all vertices and boundaries are considered identical, or coincident. The default is the inverse of the precision of the feature dataset. Feature Dataset: Name of the feature dataset which contains this topology layer. Feature Classes: List out all feature classes those will participate in the topology. Ranks: Ranks allows controlling how vertices move during validation process. Determine the number of ranks (up to 50) based on data, and the priority of the rank of each feature class in the topology. Rules: These define conditions in the topology, and are used to specify and constrain the topological relationships that must exist within the topology. Specify topology rules those will be applied and corresponding feature classes. (e)

Domains/Subtypes

Domains:

Attribute domains define additional rules/constraints for fields in table, feature class, or subtype. They are created as properties of the geo-database, and then are assigned to fields by editing the field properties of a feature class or table. The same domain may be assigned to many fields in different tables. Also, domains may be applied to all records, or to specific subtypes of records. These are used in defining legal values or defining split or merges policies for features. Following are the types of domain: • •

Range Domain Coded-value domain

Range domain specifies a valid range of values for a numeric attribute. A coded value domain can apply to any type of attribute – text, numeric, date, and so on. 330

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List and order all the identified domains needed for database by its name and describe them accordingly. Description of each domain should start from separate page. One or more pages should be devoted to the description of each domain. On the top of the page is the name of the domain and it must be unique of any length. Then describe domain as follows: domain properties, codes/ranges and values. The naming conventions for the domains are as follows: (i)

If domain is specific to a feature class then – AgencyCodeFeatureClassName_DomainName

(ii)

If domain is applicable to more than one feature class – AgencyCode_DomainName

Description: A long description of domain including need and objective.

Following example shows the naming convention used, domain properties, coded values for specifically arc feature class of vegetation feature dataset in topographic database. Name: Veg_Arc_GFCode Domain Properties

Field Type Domain Type Split Policy Merge Policy

Text Coded Value Duplicate Default Value

Coded Values GFCODE TGLESCRB TGLEWDAR TGLNHDGW TGLNTRLN TGLVMPLT TGLVNEAT

Description Scrub Extent Wooded Area Extent Hedgerow Tree Line Mapping Limit Extent Neatline Extent

Subtypes:

The geodatabase has several data integrity and data management capabilities, one of them is subtypes. The objects stored in a feature classes or table are organized into subtypes and can have set of validation rules associated with them. When to use subtypes it depends upon business requirements. For example, if we are trying to distinguish objects by their default values, attribute domains, connectivity rules, and relationship rules, it is recommended to create subtypes for a single feature class or table. If we are trying to distinguish objects based on different behaviors, attributes, access privileges, or whether the objects are multi versioned, we must create additional feature classes. The description of each subtype should start from separate page. One or more pages can be devoted to the description of each subtype needed to database. Use following subtype values and associated features those are common to all feature classes: 0

- New feature

999

- Empty feature (applicable to polygon feature class only)

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Order and description of subtypes is as follows: Feature Dataset Name: Write the name of feature dataset that will contain these subtypes. Feature Class/Table Name: Specify the name of feature class/table where these subtypes will be applied. Description of Subtypes: Write the description of each subtype and respective code. (f)

Tables

The purpose of this section is to identify all tables. List and order all the identified tables by its name and describe them accordingly. One or more pages are devoted to the description of a particular table. Each page (or group of pages) is of the same format. At the top of the page is the RDBMS table name. Other than the primary geographic feature attribute tables in ArcSDE®, there are 3 different types of tables indicated in this document. These are: MST Master Table - A primary table representing an entity and maintaining its characteristics. 1 Master Table names are given the following structure : _MST

Where GFCODE is the feature/entity GFCODE. e.g. ZZZZSTUF_MST

LNK Link Table - A table which only maintains foreign keys for the purpose of allowing relates between Master Tables (usually when a many-to-many relationship exists between them). Link Table 1 names are given the following structure : ZZ_LNK

Where Resource Area is the first 2 characters from GFCODE, and sequence is a sequential value between AAAA and ZZZZ (i.e. AAAA, AAAB, AAAC, etc.) such that the full 8 characters before the extension (LNK) are unique. e.g. TGZZAACL_LNK

2

LKP Lookup Table - A table which maintains a single column of long text, along with its abbreviation. This abbreviation is essentially a primary key to substitute for long text in Master Tables 1 thus minimizing data storage requirements. Lookup Table names are given the following structure :

ZZ_LKP

Where Resource Area is the first 2 characters from GFCODE, and abbrev is an abbreviation to represent the file such that the full 8 characters before the extension (LKP) are unique. e.g. TGZZCHPT_LKP

1 2

The underscore ("_") delimiter is used with Oracle®. In INFO®, a period (".") is used as its delimiter. A Lookup Table may maintain two columns of long text where one is in Arabic, and the other in English.

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The table is then described under the following headings:


GFCODE: An 8 letter identifier to nationally identify a unique entity or feature (geo-entity). Refer to the previous section FEATURES description (page) for generating GFCODE and more details. For primary geographic feature attribute tables (.AATs, .PATs, etc.), the GFCODE assigned must not have PV, LV, LE, LX, RV, AV, GV, or CV in character positions 3 and 4 (i.e. basic geometric representation without the qualifiers “virtual” or “extent”).




Name: The entity/feature name.




Description: A long description of what the entity is in its true existence.




RDBMS: The name of the Relational Database Management System including version number within which this table resides.




Normalization: Mention what degree of normalization such as first, second, third, etc. could have been achieved by normalizing a table, if applicable; or specify clearly why de-normalization is preferred.




Known Redundancy: An indication if there is any data in the table which exists redundantly in other tables.




Column Data Types: The breakdown of each column in the table should be identified in the following headings such COLUMN (name of the column), TYPE (what kind of value does it accept), WIDTH (how much is the width of column to accommodate the required values) and DECIMALS (number of decimal 1 places) for Oracle® tables, and CHARACTERISTICS to define domain and constraints such as acceptable values, range, validation checks, constraints for further limiting column values, unique key, primary key, foreign key etc. Note that column names can only be of maximum 10 characters in length, 2 and must not conflict with any reserve word identified within ArcSDE® or Oracle® DBMSs. For the primary geographic feature attribute tables (business tables) in ArcSDE®, a number of mandatory columns exist. Some fulfill GIS software requirements, whereas others fulfill national feature inventory requirements.




Column Definitions: A verbal description of what each column represents. If a Lookup Table (LKP) is to be referenced, and it does not have its own Appendix C entry, the Lookup Table's Column Data Types must be listed.




Owner: The agency that owns (or has been appointed as custodian for) the data in this table.




Update Rights on Columns: The agencies which are entitled to submit changes to the data in specific columns of this table.




Relate Table: A table which contains a list of all direct relationships for the given table. In case of many-to-many relates via a link table, both sectors of the related are shown on the same row.




Diagram Methods: Design documents are often simplified (abstracted) so they may be easily read and understood. Use Unified Modeling Language which is independent of process and language under the Visio environment or any latest visual tools for data and software modeling available at ESRI. ESRI provides the Visio templates needed in order to build designed model. They contain the ArcObject geo-database classes, their interfaces, and the ESRI extensions to the UML. Provide Data Model depicting relationship between feature classes, subtypes for a respective feature dataset. Also list out all domains applied for each feature class/subtype for a feature dataset. For clarity, Link Tables may be omitted. The Lookup Table that does not have its own Appendix C listing must be shown on in the model Master Tables it’s referenced with. A Lookup Table that has its own Appendix C listing must either have its own model, or be shown on the models of Master Tables it’s referenced with.

1 2

Refer Oracle® documentation for further details Refer to ArcSDE® documentation for further details.

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(g)

Relationship Classes

Geodatabase relationship classes manage the relationship between pairs of classes in the geodatabase. Relationship rules restrict the type of objects in the origin feature class or table that can be related to a certain kind of objects in the destination feature class or table. A relationship is implemented as a class in the geodatabase. Geodatabase relationship classes provide many advanced capabilities not found in ArcMap joins and relates such as read-write access, versioning support, all cardinalities, relationship rules, simple or composite, referential integrity. These are created in ArcCatalog and use them in ArcMap. Relationships are established between a pair of classes, one of which is the origin and the other is the destination. Objects in two classes are matched based on the values found in their key fields. The key fields may have different names, but must be of the same data types and contain the same kind of information. Fields of all data types except BLOB and Date may be key fields. Maintaining relationship classes requires more computer processing to maintain than joins and relates. Use them only when you need their advanced capabilities. List and order all the identified relationship classes by its name and describe them accordingly. One or more pages are devoted to the description of a particular relationship class. Each page (or group of pages) is of the same format. At the top of the page is the full relationship class name. The relationship class is then described in the following headings: Name: Relationship classes have names, like tables and feature classes, and their names must be unique within the geo-database. Use descriptive naming conventions; a label is easiest to use when its name is descriptive, like ToOwner and ToParcel. You might preface the name with the relationship, like OwnerToParcel:ToParcel. Description: A long description of the relationship class's in terms of what type of relationship, the objective, relationship rule, cardinality, need of intermediate key table, and so on. Origin Class: Write a name of origin class with breakdown of its all fields, which has an impact on referential integrity enforcement. Destination Class: Write a name of destination class with breakdown of its all fields. Key Fields: Write name of fields, data type, and their width from origin and destination classes those are going to be used for matching the values between classes. Types of Relationships: Relationship type should be written here such as simple, composite, or other types. (h)

Geometric Network Classes

There are two types of network: geometric and topologic. A geometric network is a topological relationship between line and point feature classes in a feature dataset, and a feature class can participate in one geometric network. Each feature has a role in the geometric network of either an edge or a junction. The point and line features acquire more behavior and become junction and edge features in a single, integrated dataset. Junction is of two types: simple and complex. Geometric network satisfies the needs of vector datasets required to model utility networks to support tracing through a set of connected lines and points. List and order all the identified geometric networks by its name and describe them accordingly. One or more pages are devoted to the description of a particular geometric network class. Each page (or group of pages) is of the same format. At the top of the page is the geometric network class name. The geometric network class is then described in the following headings: Name: Geometric network classes have names, like tables and feature classes, and their names must be unique within the geodatabase. Use descriptive naming conventions such as WaterNet, DrainageNet. Description: A long description of the geometric network class's in terms of what type of network such as simple or complex, the objective, and so on. Feature Dataset: Write the name of feature dataset that will contain the network.

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Feature Classes: List out all feature classes those will participate in the network. A geometric network doesn't have to include all feature classes in a feature dataset. Snapping Tolerance: Specify the map units that features are going to be snapped to and the features classes that are going to be snapped. Moreover, specify some feature classes to snap while others remain stationary. It would be required if one feature class is more accurate than another, and want the less accurate class to snap to the more accurate feature class. Connectivity Rules: Specify the network connectivity rules those constrain the type of network features that may be connected to one another and the number of features given type that can be connected to features of another type. For example, in a water network, 10-inch transmission main can only connect to an 8-inch transmission main through a reducer. Network Weights: Identify the names and type of weights will have in network and fields those weights are associated with it. Network weights are required to control tracing operations. These are three types: Ratio, Nominal, and Bitgate. (i)

Raster Datasets

The purpose of this section is to identify all raster datasets. List and order all the identified raster datasets by its name and describe them accordingly. One or more pages are devoted to the description of raster images. Each page (or group of pages) is of the same format. At the top of page is the full name of raster image such as satellite images, ortho images, etc. Description of each type of images should be started from separate page. The image is described under the following headings:


Name: It is the same name as of business table which will be stored in the database. Naming convention should include the following: Area Name: Image name should be preceded by including the meaningful name of area to which this imagery belongs such as DOHA, ALKHOR, QATAR, etc. Year: After preceding by underscore, include 4 digits for year in which image was taken such as 1994, 2003, 2009, etc. Month: After preceding by another underscore, include 2 digits for the name of a month in which image was taken such as 01 = Jan, 02 = Feb, 03 = Mar, ……, 12 = Dec. Resolution: After preceding by another underscore, include resolution of image in centimeter such as C20, C100, C2000, etc in the part of name. Source of Image: After preceding by another underscore, include three characters code suitable for the source of Image such as ORT = Ortho, IKS = Ikonos, LNT – Landsat, SPT = Spot, QKD = Quikbird, etc as a last part of full image name. For example: RASTER.ALKHOR_2008_05_C080_IKS




Description: A long description of raster image, it may include resolution of image, name of the source, date of image, source type (continuous, discrete), area of image, etc.




Storage Type: Specify the appropriate raster storage type needed such as Mosaic, catalog or any other type.




RDBMS: The name of Relational Database Management System within which this image will reside.




Known Redundancy: An indication if there is any raster dataset in the database which exists redundantly.

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Compression Method: Specify compression method needed and used to store raster image into the geo-database such as LZ77, JPEG, JPEG2000, etc, along with type of compression or percentage of compression respectively.




Data Depth: Specify the data depth of image such 8, 16.




Owner: The agency that owns (or has been appointed as custodian for) the raster dataset.




Update Rights on Columns: The agencies which are entitled to submit changes to the raster dataset.

(j)

Features

The purpose of this section is to identify all required geographic features for respective data dictionary. These are listed first by Geometric Representation (in the order shown under GFCODE below, excluding Section and Not Geographic), and then alphabetically by the Feature Name. One or more pages should be devoted for the description of a particular feature. Each page (or group of pages) is of the same format. At the top of the page is the feature name. This may be of any length, but is generally kept short. The feature name is given in the following structure:

()

Where Feature Name is given with all first letters in upper case, and Geometric Representation (see under GFCODE below) is given inside round brackets, and with all letters in lower case. e.g. Guard Rail (line) The feature is then described under the following headings:


GFCODE: An 8 character identifier to nationally identify a unique entity or feature (geo-entity). Uniqueness is only present using the full 8 characters). GFCODE is structured as follows:

♦

The first two characters in positions 1 and 2 combine to represent the Resource Area from which the entity/feature was identified. The available Resource Area values are: Table 8.10: Resource Areas of Entity/Feature

AG

Agriculture/Water

EN

Environment

SW

Sewer

CD

Civil Defense

FS

Fisheries

TE

Treated Sewage Effluent

CI

Crime Investigation

IM

Immigration & Residence

TG

Topographic

CS

Control Survey

NS

National Statistics

TL

Telecommunications

DA

Drainage

PD

Municipal Planning & Development

TP

Traffic & Patrol

DI

Demographic

PS

Police Services

TR

Traffic Management

ED

Education

RD

Road

WT

Water

EI

Economic

RE

Real Estate

ZZ

Common

EL

Electricity

SG

Surface Ground Water

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♦

The characters in positions 3 and 4 combine to represent the Geometric Representation of the entity/feature. The available Geometric Representations are as follows: PT PV LN LE LX LV ND NV AR AV GN GV RT RV EP EL EC TX CX CV PX SC ZZ

♦

Point Point Virtual Line Line Extent Line Extent Virtual Line Virtual Node Node Virtual Area Area Virtual Region Region Virtual Route Route Virtual Event/Point Event/Linear Event/Continuous 1 Text Complex Object Complex Object Virtual Pixel Cell Section Not Geographic

Given the Resource Area and Geometric Representation identifiers, the characters in positions 5, 6, 7, and 8 combine to identify a particular entity/feature. If numbers are to be used in positions 5, 6, 7, or 8, in order to avoid confusion between letter “O” and the number zero, the only valid configurations of letters (“L”) and numbers (“N”) are as follows: Position 5

6

7

8

L

L

L

L

L

L

L

N

Remarks

no letter “O” in position 7

L

L

N

N

no letter “O” in position 6

L

N

N

N

no letter “O” in position 5

N

N

N

N

♦

Virtual applies to objects which require geometric representation, but do not physically exist (e.g. Administrative areas or boundaries).

♦

Extent applies to linear objects which only exist to delineate the limits of areas.




Definition: A long definition of the feature. This will describe what the feature is in its true existence (not how it will be geometrically represented).




Aliases: A list of any aliases or alternative spellings for the feature name.




Feature Dataset: Name of feature dataset within which the feature can be found.

1

Text is available as a Geometric Representation since it fulfills cartographic demands that can't be satisfied by other means. However, it should be noted that where the text string labels characteristics for a coded geometric object, the content of that text string must not be considered as the primary source of that characteristic. The characteristic's primary source is its attribute association with the geometric object.

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Feature Class(es)/Object(s): Name of feature class(es)/Object(s) within which the feature can be found. A list of more than one feature classes/object(s) represents the presence of redundancy in feature geometry.




Geometric Representation: An explanation of how an object's true shape and position (and possibly orientation) are geometrically represented.




Sharpness: An indication of how fixed & distinct the feature is. This essentially classifies features in 1 terms of their potential to have a significant degree of positional accuracy associated with them . Valid options are:

Well Defined – always having a very fixed & distinct shape. Not Well Defined – never having a fixed & distinct shape. Mixed – fixed & distinct in shape in some cases, but not in others. Not Applicable – feature for which Sharpness does not apply (such as cartographic text). Examples: Any diagrams, images, etc. which add to the clarity of how the feature is to be identified either on site, or in the GIS Database.




8.5.4

Accuracy of GIS Database

The issue of accuracy is dealt with in this section under 4 general headings. These are: 1. 2. 3. 4. (a)

Positional Accuracy (correctness) Characteristic Accuracy (correctness of attributes) Data Currency Completeness Positional Accuracy

For determining positional accuracy, one undertakes computation of the exact range from an object's measured position within which its true position will fall. This is dependent on numerous factors. In the data dictionary, the computed positional accuracy is not recorded for any objects. However, there are three values which are stored against each which allow the user to gauge the data's positional accuracy. These are:

1

SOURCE

The unique identifier of a specific positional data capture history, which has generated the current positional values. The source of capturing data could be such as CGIS (Surveyed by their team), Outsourced company, digitized from ortho images, digitized from Satellite images, digitized from scanned document and so on.

RELIABLE

A subjective estimate of a position's reliability as indicated by the layer owner. It is indicated as a plus or minus value in the same units as the positional data. As of today, the acceptable values are Reliable, Moderate and Fair.

CONFIDENCE

The expected frequency, expressed as a percentage, with which the position will be within the tolerance expressed by RELIABLE. We are choosing a level of certainty or a level of confidence such as 99%, 95%, 90%, and so on.

Positional accuracy requirements for future “survey / data collection” exercises of a particular feature are listed in the Qatar National GIS Survey Specification (not yet produced at the time of this document’s printing).

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Most applications will be able to rely on the RELIABLE and CONFIDENCE values alone. More rigorously determined accuracy could be established by interrogating the details available via the SOURCE field. This field allows linkage to the following details, defining how a position was established:







Other sources used Tasks performed Methods used Equipment used Specifications under which each source was produced Agencies involved

The means by which these details are accessed are mapped out in the ERD in Figure 8.7.

constitute part of

consist of

be used by

Source

Resource Custodianship Appointment

of have available

Resource Type

be created by

conform to

use create

be issued to define

Specification

receive

issue

be used by

be issued by

be qualified to perform

Project

use be generated by

generate be used by

be a qualified service of

use

Method

divide into

have be for

be a division of spawn

Equipment Custodianship Appointment

be spawned by

Agency

be credited with

be credited to

Equipment Purchase

manufacture

be manufactured by

Task

form part of

constitute part of be made by

be of

consist of

consist of

make

Equipment Requirment

constitute part of

Equipment Type identify the classification of be classified as

Equipment be used by

use

have been done by

have done

Figure 8.7: Entity Relationship Diagram of Positional SOURCE Details

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(b)

Characteristic Accuracy

If they are required, accuracy for characteristics will be recorded in separate columns. Typically, measured values (which includes date & time values) will have their accuracy recorded in columns much like RELIABLE and CONFIDENCE in the previous Positional Accuracy section. Columns carrying text (alpha, numeric, or both) may have their accuracy recorded in columns that indicate "Verified/Unverified" values. In the case where translations are involved, additional columns may be used to indicate if the translation is phonetic, or based on meaning. (c)

Data Currency

Via the SOURCE column, all tasks associated with the establishment of an object's position can be queried. The START and FINISH date characteristics recorded for these tasks indicate when an object was positioned, but they do not give any indication of whether or not anything has happened since. Has it since been destroyed? Has something new gone up in the vicinity? To determine when an area was last examined for any changes, a change verification START and FINISH 1 date exist as characteristics against each tile . In some cases, changes may take place in a portion of a tile during the examination for changes. If that change is in an area already examined, it will not be picked up. Thus, the change verification START date for a tile is the date one can rely on as an indication of how current a position is. Where required, the currentness for any characteristic of any entity or feature, are established by one or more date last examined columns. These reflect the last time when one or more characteristics were verified. One last date characteristic which is of particular importance is the date a piece of data became available on 2 the database . For position, this is stored in the DATE_LUPD (date of last update) column of the business table of feature class. Where required for characteristic values, similar date fields are added.

1

2

A Layer can extend, geographically, to infinity. It is often more practical to geographically partition a layer into more manageable areas. Each of these is referred to as a Tile. For historic data, the date of removal carries a similar level of significance.

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References

CGIS Topographic Data Dictionary Metadata Details document of CGIS CGIS Data Dictionary and Specifications CGIS Database Design Document

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Appendix 8A Eligible GIS Member Agencies Center for GIS (CGIS)-State of Qatar Serial #

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Agency Name

Real Estate Registration Department (RERD)/Ministry of Justice Statistical Department/Planning Council Electricity/Qatar General Electricity and Water Corporation (KAHRAMAA) Water/Qatar General Electricity and Water Corporation (KAHRAMAA) Qatar Telecommunication (QTEL) Roads/Drainage Public Works Authority (PWA) Ashghal Qatar Petroleum Corporation (QP) (it Includes around five sectors/departments) Lands Affairs Sector/Urban Planning and Development Authority-UPDA (It includes three Departments) Planning Affairs Sector/Urban Planning and Development Authority-UPDA (It includes three Departments) Agricultural Information center (AIC) Ministry of Interior (MOI) Supreme Council For Environment and Natural Resources Department of Agricultural and Water Research (DAWR) Department of Agriculture and Development (DAD) Qatar University Building Engineering Department/Public Works Authority (PWA) Ashghal Ministry of Education (MOE) Civil Defense Department Ministry of Awqaf and Islamic Affairs Olympic Games Committee State Security Intelligence (SSI) Internal Security Force Qatar Armed Forces (Head Quarter) Al-Daayen Municipality Doha Municipality Rayan Municipality Al Khor Municipality Al Wakrah Municipality Al Shamal Municipality Technical Affairs- Doha Municipality

To continue

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Appendix 8A (continue) Eligible GIS Member Agencies Center for GIS (CGIS)-State of Qatar

Serial #

31 32 33 34 35 36 37 38 39 40 41 42 43 44

Agency Name

Health Affairs- Doha Municipality Umm Salal Municipality Mechanical Engineering Department Animal Health Affairs Agricultural Central Lab Central Market - Salwa Road Fisheries Department Ministry of Municipal Affairs and Agriculture (MMAA) Head Quarter Building Permit Complex (It includes UPDA, Kahrammaa, PWA, Civil Defense, Qtel, Doha Municipality Offices) State Audit Bureau Courts Private Engineering Office (Ameri Dewan) Hamad Medical Emergency Services (Ambulance) Hamad Medical Corporation (HMC)-Head Quarter

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Document Control Page Document version:

1.0

Document status:

Current

Document owner:

Urban Planning & Development Authority, Qatar

Date printed:

30 May 2009

Document name:

Qatar Survey Manual

Revision history of this document: Version Number

Revision Date

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