Issue with terrain correction

Hi everyone!

I have pre-processed a Sentinel-1 GRD tile. The steps include: Thermal Noise Removal, Calibration, Speckle Filtering and Terrain Correction. I’ve used the 1 arc second DEM.

However the hills don’t look correct. Anyone know why this is?

Range Doppler Terrain Correction only corrects the geometric distortions caused by the looking angle. The radiometric effects are still present, e.g. over-illumination of slopes facing the sensor.

To compensate for these effects, you have to include Terrain Flattening:

  1. Thermal noise removal
  2. Calibration to Beta0
  3. (Speckle filtering)
  4. Radiometric terrain flattening
  5. Range Doppler Terrain Correction

Thank you Braun!

I will try it.

ps. It is not recommended to put terrain flattening and terrain correction in the same processing-chain for performance-reasons.


I’m working with snappy. Would this mean these are the steps:

  1. Thermal noise removal
  2. Calibration to Beta0
  3. Speckle filtering
    4a. Radiometric terrain flattening (speckle filtering as input)
    4b. Range Doppler Terrain Correction (speckle filtering as input)

If so, how would I merge the two outputs before converting to db?

Thank you.