If you want to convert sigma 0 to gamma 0 (\ Radar \ Radiometric \ convert sigma 0 to gamma 0), DO NOT RECOGNIZE IT, in 1C and 1D formats. The angle of incidence is not in the metadata. Calculating the local angle of incidence for the L1C and L1D would not be straightforward, and could be done with calculations that consider orbital geometry. Errors also occur with 1A SLC formats, which cannot be orthorectified. Polarimetric analysis can be started, but it is impossible to correct geometrically. For SNAP to read the 1A SLC, all the incident angle files and NES0 files must be removed from the “Data” directory and copied elsewhere, otherwise, SNAP gets confused and reads it wrong. That is, you just must leave the SLC images with their associated XML. But after all, analysis is one frustration after another. Does anyone have any suggestions for these problems? I need to solve two main issues:
I need the L1A SLCs to be able to apply the polarimetric algorithms and obtain for example the classification maps that would remain in slant-range geometry (they would not be geocoded), and
On the other hand, you would need the incidence angles to be able to calculate the Gamma on the one hand and to do the orthorectification of both the Gamma and the results of the polarimetric classification (which would be in slant-range geometry).
The incidence angle for SAOCOM products is provided as tie point grid (see attached figure) which can be used directly in the generation of gamma0 using Band Maths in SNAP. Also, for the reported problem on 1A SLC orthorectification, we have tested the 1A SLC we have with the Range-Doppler Terrain Correction operator and did not find any problem. You can upload your screenshot of the error message and we can look into it again
Dear Jun_Lu,
Thank you very much for your advice, I was able to calculate it in band maths, I made a mistake not considering this option. Anyway, the band maths gives me information gaps (see the screenshot). This version 8 has a lot of problems. I had to uninstall and I am using version 7.
Thank you very much for the reply. I’ve seen the forum and the problems that Geonow raised. My students and I, we had detected this problem as soon as we installed version 8. The error with BandMath is serious. In our examples the algorithm does not work saving the bands created with BandMath, the image does not look good, especially in radar images. This happens when we use both the products individually or integrally with the collocate algorithm.
