I did a drone flight using 30 RTK surveyed GCP’s in order to generate an accurate DSM to be compared against survey data. I set and surveyed 30 GCP’s with high accuracy RTK-GPS, but every time I generate a DSM, the resulting elevation values (ft) are negative and I cannot figure out why. I have tried just about every setting including using using the default Geoid setting, using the height above ellipsoid, and also arbitrary for veritical coordinate system. Reading forum posts and my own trial and error seem to point to using arbitrary as the best results but I still can’t get the correct values. Has anyone else experienced this or know of a solution?