I have two DEMs of a stream channel created with photogrammetry from different times. One of the DEMs used ground control points and is georeferenced correctly. The other model did not use ground control points, but was georeferenced with the gps on the drone used to collect the imagery and was corrected using satellite imagery.
To correct elevation on the DEM I used a DEM of difference between the two, found the mode of the elevation values and added it to the DEM. This worked amazingly well, however there appeared to be a slight, north/south tilt to the DEM. I took several sample from a nearby road and found the mode of those, and then plotted them and found that there is a 1 to 2 meter tilt from the north end to the south end:
I am trying to use something of the form:
new_band =
for [i] in length 1:y[i]{
zdif_south + dist_north * (zdif_south - zdif_north)/z[y[i]]
}
I have tried to figure it out in the raster calculator and in python console in QGIS. One problem I am having is I don't know how to index the xy in raster datasets.
Has anyone done anything similar to this?