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I am using the Georeferencing tool/plugin in QGIS 3.1 to try and 'rubber sheet' two layers together. My reference sheet is a LiDar data set (ESPG 2961- NAD 83), pixel size 0.0709, -0.0709. The sheet I am trying to fit is a dated UAV DSM file. The two layers have a difference in elevation by ~5-10m. The problem I am having is that when I run the Georeferencing tool, the new 'georeferenced' layer is shown to have a NULL Z-value (1.79+308 being the max limit of computations-see photo below).

The data are taken of a coastal shoreline and I am measuring elevations of the intertidal area, so bare rock, sand, etc. I have posted photos of the methodology below:

Here is what the issue looks like- this photo is of the UAV layer post-rubbersheeting:

Here is what the issue looks like- this photo is of the UAV layer post-rubbersheeting

My process was as follows:

  1. Select 20 GCPs from around both layers so that they are uniform.
  2. Use the following transformations: 'Thin Plate Spline', with the resampling type of 'Cubic Spline'.
  3. Let run

UAV derived DEM with elevations on legend:

UAV derived DEM with elevations on legend.

LIDAR derived DEM with elevations on legend:

LIDAR derived DEM with elevations on legend.

Georeferncing toolbar open showing chosen GCPs from both reference layer and new layer:

Georeferncing toolbar open showing chosen GCPs from both reference layer and new layer

I am new to this tool, and ideally would be doing something like this in Pix4D or Global Mapper but I don't have access to the datum files for either layer so am unable to figure out the issues and fix them using those applications.

Is it possible to even use this tool on a UAV DEM file with z-values? IF yes, is there a way to run the program without getting NULL values? If not- are there other applications that work similarly?

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