Raster DEM projection rendering problem

Question

I am new to QGIS and am using it primarily for the DEMto3D plugin. My use case is creating STL meshes so I can CNC carve scale models of the landscape features as art pieces.

I purchased one meter ortho-rectified Raster DEM data from a commercial provider in the BIL format, and they provided me with a projection file that looks like this:

GEOGCS["Geographic Coordinate System",DATUM["D_WGS84",SPHEROID["WGS84",6378137,298.257223560493]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

I named it as the root of the *.bil filename, and when I load the BIL into a new raster layer it does read in the custom *.prj, (I see "OGC:CRS84" in the lower right) but renders it as viewed from about a 15 deg angle from the south, instead of straight down as I was expecting. Naturally this is a foreshortened view when I want the rendered data to look like the physical feature, when viewed from straight above, so that DEMto3D creates an STL mesh that looks like the real feature.

Although it shows that I have the "correct CRS", I don't see the view I need.

Seems that there is something else going on somewhere that is overriding my CRS. There is obviously something basic that I am missing.

How can I get the rendered view "straightened out"?

It appears to be a projection issue based on what I am seeing, but with my inexperience, who knows?

I am using QGIS 3.28

Answer 1

Your DEM is in a geographic CRS (coordinate are in degree and reference the location on an ellipsoid).

If you dont set a specific projection QGIS use by default an less than adequate projection (Plate Carré if I remember well) to display it on your 2D screen. This often result as objet appearing tilted due to the deformation caused by the projection.

To "straightened out" the view you need to set the project CRS to a suitable projection for your area.

Depending on how the DEMto3D plugin work you may need to reproject your raster to get good result (if you dont reproject you will need to set some vertical exaggeration depending on the latitude, this is because the lat/lon is in degree while the elevation unit is probably meter ; the vertical exaggeration will "convert" the elevation to match the lat/lon unit)