I have a problem with the selection of S1 images (SLC) for the creation of a good DEM. I tried to download many pairs of different images with a short time difference and big baseline between there, but at the end of coregistration i saw that the coherence estimation was not good. The histogram obtained from coherence estimation tool hadn’t 70% of frequency values over 0,4 of coherence values. That isn’t a good result, if i understand well: infact the DEM that i obtained have a lot of errors and is “foggy” in many areas and elvetion values don’t correspond to SRTM DEM elevetions. Now i ask you if there is a quickly method of selection of the images. There is a method to understand if two images are coherent without necessarily having to carry out coregistration first and then the coherence estimation? In the end i want to understand why two images are coherence between there or not, what is the parameters that determinate it?
I have another question, what is the best method to use S1 datas for recognition forestry formations, or what is the best method to improve the forestry cover obtain with S2 datas with S1 products?
Thank you a lot.