hmm is a heightmap meshing utility.
If you've done any 3D game development, 3D printing, or other such things, you've likely wanted to convert a grayscale heighmap image into a 3D mesh. The naive way is pretty simple but generates huge meshes with millions of triangles. After hacking my way through such solutions over the years, I finally decided I needed to write a good tool for this purpose.
hmm is a modern implementation of a nice algorithm from the 1995 paper Fast Polygonal Approximation of
Terrains and Height Fields by Garland and Heckbert. The meshes produced by hmm satisfy the Delaunay condition and can satisfy a specified maximal error or maximal number of
triangles or vertices. It's also very fast.
brew install boost glm # on macOS
git clone https://github.com/fogleman/hmm.git
cd hmm
makeusage: ./hmm --zscale=float [options] ... infile outfile.stl
options:
-z, --zscale z scale relative to x & y (float)
-x, --zexagg z exaggeration (float [=1])
-e, --error maximum triangulation error (float [=0.001])
-t, --triangles maximum number of triangles (int [=0])
-p, --points maximum number of vertices (int [=0])
-q, --quiet suppress console output
-?, --help print this message
hmm supports a variety of file formats like PNG, JPG, etc. for the input heightmap. The output is always a binary STL file.
The only other required parameter is ZSCALE, which specifies how much to scale the Z axis in the output mesh.
./hmm input.png output.stl -z ZSCALE
You can also provide a maximal allowed error, number of triangles, or number of vertices. (If multiple are specified, the first one reached is used.)
./hmm input.png output.stl -z 100 -e 0.001 -t 1000000
- add a solid base (coming soon)
- pre-triangulation filters? e.g. gaussian blur
- export a normal map?
- automatically compute some z scale?
- better error handling, especially for file I/O
- better overflow handling - what's the largest supported heightmap?
- thread pool doesn't help much usually - get rid of it?
- OpenCL rasterization?
- mesh validation?