Since MODIS Imagery Orthorectification (Open Source) had no answer, I will try to get one here with a similar problem:
I got some raster datasets with GCPs in lat/lon, but without height information. When I use gdal to project/re-project the data, I get an offset of approx. 2km, which I think comes from terrain distortion. Using ESA's SNAP Toolbox, I get the results I want, but they are using the actual SRTM DEM in the background.
Is there a way to provide gdal with the raster, the GCPs and a DEM to get everything done "at once" (or in several steps)?
So far, my approach (which gives the offset) looks like this:
gdal_translate -gcp pix1 line1 x1 y1 -gcp pix2 line2 x2 y2 (...) input.tif output.tif
The data are SAR raster from ERS-1, which might have something to do with the offset due to the viewing angle of the sensor