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Icon by Freepik, Banner photo by Thiago Medeiros Araujo
Check out how Winston Moy's video on making a topographic map of Colorado. They mention these data sources:
OpenSCAD's surface primitive can turn height maps into STL files.
You may have to trim the state boundaries yourself. :(
Thanks! I've made lots of wide area and close-up terrain models using DEM and lidar before, but trimming to state boundaries has always been the challenge. Every time I try to trim the raster data in qgis I don't get anywhere, even though it should be possible.
The OpenSCAD primitive is a new one for me though - thanks! In the past I've just used the DEMto3D plugin in qgis.
If you can get state boundary image data coincident with height map data (such as by taking two screenshots on the USGS website, one with the heightmap data opaque and with it translucent, without panning or zooming between), you could use a normal image editor (eg: GIMP) to mask the height map data so that it's zero (black) outside the state boundary and at least slightly gray inside the state boundary. With OpenSCAD's surface, this would give you a rectangle that's flat outside the state and at some minimum height inside the state. You could then use one difference or intersection to cut across the model by height, trimming off the flat rectangular base.
(I.e., doing the trimming the image seems much easier than trimming an STL, & would totally work.)
Ah interesting - that makes sense. I didn't think to treat it like an image mask like that. Thanks!