Rapport ENVI.docx

Abdelmalek Essaadi University National School of Applied Sciences Tétouan

Report : Introduction to Remote Sensing NOAA-AVHRR Digital Image Processing

Done by :

Supervisied

by : -

EL BAKKOURI Mehdi

- DR.RAISSOUNI Naoufal

5TH YEAR TELECOMS ENGINEERING

2016/2017

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INTRODUCTION : The present practice has a double objective: first, to familiarize with the use of the ENVI (The Environnement for Visualizing Images) for the satellite digital image processing, and second, the use of the Band Math to compute some of the studied biophysical parameters, such as the NDVI, ԑ,∆ ԑ,Ts.

OBJECTIVES:  Distribution and presentation of a scene of digital data.  Familiarization with the ENVI software for the satellite digital image processing.  Application of some digital filters.  Image to image geometric correction of AVHRR-NOAA of Morocco: From Lambert to Homolosine.  The use of the ENVI Band Math to compute: NDVI, the emissivities ԑ and ∆ԑ and finally Ts. The data correspond to the AVHRR-NOAA channels 1, 2, 4 and 5 of the Mediterranean Basin of the Pathfinder AVHRR Land (PAL)-NASA/NOAA project during the month of august, 1982.  Presentation of results.

MATERIAL : The biophysical parameters computation: The Mediterranean basin images: (August, 1982) Channel 1 (M828c1b; reflectivity x 1000, mascara = -1), Channel 2 (M828c2b; reflectivity x 1000, mascara = -1), Channel 4 (M828c4b; Temperature in K x 10, mascara = -1) and Channel 5 (M828c5b; Temperature in K x 10, mask = 1).Format: 695 columns, 316 rows, Integer Host (Intel), Homolosine projection.

REALIZATION : With the ENVI Band Math compute the :

NDVI = (NIR-R) / (NIR +R) R: Red Band NIR: Near Infrared Band. First, we add the two images (R and NIR) :

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Then , we use the bad math to calculate the NDVI, using this formula :

(float(B2)-float(B1))/(float(B2)+float(B1))

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For a constant atmospheric water vapor W= 1 g cm-2. Compute the image of Ts given by the split-window algorithm given by Sobrino and Raissouni (2000): [J. A. Sobrino and N.Raissouni, 2000, "Toward remote sensing methods for land cover dynamic monitoring: application to Morocco", International Journal of Remote Sensing, 21, 2, 353-366].

Ts = T4 + 1.4 (T4-T5) + 0.32 (T4-T5)2 + 0.83 + (575W) (1-ԑ) - (161-30W) ∆ԑ  We have 3 cases :  Case 1 :

First we wiill start with the calculationg of Pv :

Using this formula :

(b1 LE 0.5 AND b1 GE 0.2) * ((b1-0.2)*(b1-0.2)/float(0.09))

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The calculation of :

(b1 LE 0.5 AND b1 GE 0.2) * ((0.968+0.021*b2))

The calculation of :

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(b1 LE 0.5 AND b1 GE 0.2) * ((0.974+0.015*b2))

The calculation of :

(b1 LE 0.5 AND b1 GE 0.2) * ((b2+b3)/2)

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The calculation of :

(b1 LE 0.5 AND b1 GE 0.2) * (b2-b3)

Now we add the T4 and T5 images.

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Finally ,the calculation of TS.

First case :

(b1 LE 0.5 AND b1 GE 0.2) * (b4+1.4*(b4-b5)+ 0.32*(b4-b5)*(b4-b5)+0.83+52*(1-b3)-131*b2)  Case

2:

The calculation of :

(b1 LT 0.2 ) *(0.980-0.042*(b2/1000))

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The calculation of :

(b1 LT 0.2 ) *(-0.003-0.029*(b2/1000)) Then the TS

(b1 LT 0.2) * (b4+1.4*(b4-b5)+ 0.32*(b4-b5)*(b4b5)+0.83+52*(1- b3)-131*b2)  Case 3 :

So we calculate directly the Ts, using this formula :

(b1 GT 0.5) * (b4+1.4*(b4-b5)+ 0.32*(b4b5)*(b4-b5)+0.83+52*(1-0.99))

Finally we add the Ts of the 3 cases and we convert the Ts to C° using the formula :

(b1+b2+b3)-273.15

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INTRODUCTION TO REMOTE SENSING