Radiometric Terrain Corrected (RTC) image is fundamental in SAR temporal analysis. It provides basic, consistent data for further analyses including change detection or time-series investigation from detected SAR data.
Proposed development of RTC in SNAP software is as follows:
- Check whether SAR data requires external orbital improvement. This is the case of ERS, Envisat or Sentinel-1, for instance
- Calibration: Use Radar >> Radiometric >> Calibrate menu. Output must include beta nought (beta-zero)
- Multilook, due to imbalance DEM and image resolutions (most likely). Use Radar >> Multilooking
- Terrain Flattening: Use Radar >> Radiometric >> Radiometric Terrain Flattening
- Terrain Correction: Use Radar >> Geometry >> Terrain Correction >> Range-Doppler Terrain Correction. The output is in gamma-nought (gamma-zero)