Category Archives: Research Notes

How to synthesize Radiometric Terrain Corrected (RTC) image

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:

  1. Check whether SAR data requires external orbital improvement. This is the case of ERS, Envisat or Sentinel-1, for instance
  2. Calibration: Use Radar >> Radiometric >> Calibrate menu. Output must include beta nought (beta-zero)
  3. Multilook, due to imbalance DEM and image resolutions (most likely). Use Radar >> Multilooking
  4. Terrain Flattening: Use Radar >> Radiometric >> Radiometric Terrain Flattening
  5. Terrain Correction: Use Radar >> Geometry >> Terrain Correction >> Range-Doppler Terrain Correction. The output is in gamma-nought (gamma-zero)