Sources
Landsat
Two Landsat sensors, 7 and 8, were used for determining the built-up areas in 2000 (Landsat-7) and 2017 (Landsat-8). The Landsat constellation yields a long-running historical archive of the entire country that is unavailable through other sources.
For this analysis the Level-1 Precision Terrain corrected (L1TP) was used, providing scenes that are calibrated across both Landsat-7 and Landsat-8. The scenes were not atmospherically corrected, but this source of error was minimized in the analysis by the use of band indices as the source of input, which helps in 'canceling out' atmospheric effects.
Six spectral bands were used from both sensors, and these were used to generate band indices.
| Name | L7-Wave length | L7-Bands | L8-Wave length | L8-Bands |
|---|---|---|---|---|
| Blue | 0.45 - 0.52 µm | B1 | 0.45 - 0.51 µm | B2 |
| Green | 0.52 - 0.60 µm | B2 | 0.53 - 0.59 µm | B3 |
| Red | 0.63 - 0.69 µm | B3 | 0.64 - 0.67 µm | B4 |
| NIR | 0.77 - 0.90 µm | B4 | 0.64 - 0.67 µm | B5 |
| SWIR1 | 1.55 - 1.75 µm | B5 | 1.57 - 1.65 µm | B6 |
| SWIR2 | 2.08 - 2.35 µm | B7 | 2.11 - 2.29 µm | B7 |