does range doppler terrain correction change inherent values in in level 1 data in orthorectifying the selected image?
this depends on the setting. If you select nearest neighbor interpolation, the values are preserved. The standard (bilinear resampling) slightly changes the pixel values while projecting the image.
Thanx for your reply .
I have one more question. I have found two method of orthorectification 1. Range doppler terrain correction (RDTC), 2. SAR-Simulation Terrain Correction (SARSimTC) . Which one of the above method gives more accurate result with least chage in pixel value?
Orthorectification of Sentinel-1 SAR (Synthetic Aperture Radar) Data Using Sentinel-1 Toolbox
Thanx again in advance.
regarding the geometric accuracy both are fine, but Range Doppler Terrain Correction is more common for Sentinel-1 data.
The change of pixel values is determined with the resampling method. If you want to keep the input values you have to select Nearest Neighbor interpolation.