To get an incident angle of Sentinel-1 using snappy, I used two approaches.
- To create a new band “incident_angle” using Band Math in SNAP. And then reading pixels for that band using snappy for particular pixels (x,y).
- To use getRasterDataNode(‘incident_angle’) function to get an object and reading pixels into numpy array using readPixels.
When I approached my problem with two different approaches, I am getting slightly different values of incident angle. For some examples where I checked, I got following values -
case 1 (some x,y)-
- 31.569101333618164 (1st approach)
- 31.56910178519918 (2nd approach)
So as seen there is difference between these values (order of 10^-5). But can I know the reason behind getting this difference? Is Band Math add some processing before converting into the band? Also, for your information, I have tried both techniques after application of orbit files. Is it creating this difference?