[quote=“Paul_Griffiths, post:9, topic:31137”]I imported the DEM into QGIS (http://www.qgis.org/en/site/). I reprojected the raster DEM to WGS84 and exported it as a UTM XYZ ASCII point file.
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QGIS will automatically warp the raster file from its initial spatial reference system, to the target one (UTM). You do not have to reproject it to the WGS84 first and then to UTM.
@cwreckord
A lot of useful advises have been given in this topic. Just a small addition on the issue of spatial references, as I have been having similar ones lately.
A raster (topography) file of any sort (.tif, .asc, img…) , can not be imported into Rhino by “non-georeferencing” methods without checking its spatial reference system first. Plugins and applications like Rhino Terrain and Autocad Civil 3D do contain this option. But Heightfield command does not.
This is also true for vector files, but this topic is dealing with raster ones.
A raster file you downloaded should have a small .prj file downloaded next to it. It contains a WKT string representing a spatial reference of the raster file.
According to this spatial reference, you would need or need not to reproject the raster to an appropriate spatial reference system. This depends on a lot of factors, the purpose of the map, local geodetic regulations…
What do you intend to use your topography file for?