Tutorial Konversi DN Landsat 8

TUTORIAL LANDSAT 8 MENGGUNAKAN SOFTWARE ER MAPPER Nilai multiplicative ML menggunakan nilai MULT di metadata citra Landsat 8 Nilai additive AL menggunakan nilai ADD di metadata citra Landsat 8 a. Radiance Lλ = MLQcal + AL Keterangan: Lλ = TOA spectral radiance (Wm-2sr-1μm-1) ML = Band-specific multiplicative rescaling factor from the metadata AL = Band-specific additive rescaling factor from the metadata Qcal = Quantized and calibrated standard product pixel values (DN) Rumus Algoritma di ER Mapper: Radiance band 1 = if i1=65535 then null else (0.012483*i1-62.41534) Radiance band 2 = if i1=65535 then null else (0.012729*i1-63.64723) Radiance band 3 = if i1=65535 then null else (0.011656*i1-58.27939) Radiance band 4 = if i1=65535 then null else (0.0098718*i1-49.35907) Radiance band 5 = if i1=65535 then null else (0.0059903*i1-29.95164) Radiance band 6 = if i1=65535 then null else (0.0015093*i1-7.54632) Radiance band 7 = if i1=65535 then null else (0.00049096*i1-2.45480) Radiance band 10 = if i1=65535 then null else (0.0003342*i1+0.1) Radiance band 11 = if i1=65535 then null else (0.0003342*i1+0.1) b. Temperature Brightness (Tb) Berdasarkan rumus Plank, maka spectral radiance dirubah menjadi temperature brightness Tb = (

Keterangan: Tb K1 band 10 K2 band 10 K1 band 11 K2 band 11 Lλ

)

= Temperature Brightness (K) = 774.89 (Wm-2sr-1μm-1) = 1321.08 (K) = 480.89 (Wm-2sr-1μm-1) = 1201.14 (K) = Spectral radiance pada kanal ke-i (Wm-2sr-1μm-1)

Rumus algoritma: Tb 10 = (1321.08/log(1+(774.89/i1))) Tb 11 = (1201.14/log(1+(480.89/i1)))

c. Reflectance ρλ' = MρQcal + Aρ Keterangan: ρλ' = TOA planetary reflectance Mρ = Band-specific multiplicative rescaling factor from the metadata Aρ = Band-specific additive rescaling factor from the metadata Qcal = Quantized and calibrated standard product pixel values (DN) Rumus algoritma di ER Mapper: Reflectance band 1 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 2 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 3 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 4 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 5 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 6 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 7 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 10 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Reflectance band 11 = if i1=65535 then null else (0.00002*i1-0.1)*1000 Nilai reflectance bernilai desimal, sehingga menggunakan faktor perkalian 1000 sehingga nilai reflectance nya bernilai ratusan. TOA reflectance dengan koreksi sudut matahari menjadi: ρλ = = Keterangan: ρλ = TOA planetary reflectance θSE = Local sun elevation angle. θSZ = Local solar zenith angle; θSZ = 90° - θSE

d. NDVI NDVI = NDVI = Normalized Difference Vegetation Index NIR = Band Near Infra Red (band 5) IR = Band Infra Red (band 4) e. EVI Perhitungan EVI berdasarkan persamaan (Heute et al 1999): EVI = 2.5 (R2 –R1)/(1 + R2 + 6R1 –7.5R3 ) Dimana : R1 = Reflektansi kanal infra merah dekat (NIR)

R2 R3

= Reflektansi kanal infra merah (IR) = Reflektansi kanal biru

Rumus penentuan suhu permukaan LST MODIS = - 457 + 4.47 Tb 10 - 0.644 Tb x - 9.13 NDVI + 8.87 EVI

Tb 10: Temperature Brightness band 10 Tb x : (Temperature Brightness band 10 x Temperature Brightness band 10)/100 NDVI : nilai NDVI EVI : nilai EVI