Hi! I’ve performed interferometric formation for DSM generation across two different locations containing boreal forests (Vindelfjäll nature reserve, Sweden & Malla strict nature reserve, Finland). I’ve used two image pairs with a tbaseline of 6 days and a pbaseline >150 taken during dry days and gotten quite good results. The only problem I have is that the elevation retrieved across Malla strict nature reserve is showing some height underestimation (up to -40m) in levelled terrain and height overestimation in mountainous regions (very unexpected) while the one in Vindelfjäll nature reserve is showing an overestimation in the levelled terrain (+50m) and underestimation in the mountainous areas (expected). Both DEMs used are measuring from the ellipsoid so I know its not that, I’ve also checked if slope degree and aspect could explain these differences but I couldn’t find any correlation. Lastly I checked if local incidence angle could explain it but can only find a very low positive correlation of 0.2 (1 = strong positive correlation).
Does anyone have any clue what might be the problem? I’ve tried with several image pairs over this location and seem to get similar results every time.