I would like to create a RGB image using Sentinel 1 data. It appears the standard way is to assign VV, VH, and VV/VH for the R, G, and B channels. I do, however, have a two questions.
One. It is unclear to me if the VV and the VH bands referred to by folks have already been log-transformed and are in dB scale.
Two. I have tried various combinations--log-transform VV and VH or not; log(VV)-log(VH) vs log(VV)/log(VH); etc--but I cannot get my RGB image to show a blue color for water as seen in the image attached.
I suspect that is because of the upper and lower bounds of the VV and VH values one picks when transforming floats to integers. (For example, I think Google Earth Engine sometimes clip values outside of -25 and 0 and re-scale the rest to 0 to 255. And the -25 to 0 range seems to suggest that the VV and VH are in dB-scale?) Is there a standard way of picking the range so I can get the water to show a nice shade of blue?
P.S. The source of the image is page 21 of https://appliedsciences.nasa.gov/sites/default/files/SAR_Part1.pdf.