Saturday, 13 December 2014

V-HACD 2.0 Parameters Description



Parameter name Description Default value Range
resolution maximum number of voxels generated during the voxelization stage 100,000 10,000-64,000,000
depth maximum number of clipping stages. During each split stage, all the model parts (with a concavity higher than the user defined threshold) are clipped according the "best" clipping plane 20 1-32
concavity maximum concavity 0.0025 0.0-1.0
planeDownsampling controls the granularity of the search for the "best" clipping plane 4 1-16
convexhullDownsampling controls the precision of the convex-hull generation process during the clipping plane selection stage 4 1-16
alpha controls the bias toward clipping along symmetry planes 0.05 0.0-1.0
beta controls the bias toward clipping along revolution axes 0.05 0.0-1.0
gamma maximum allowed concavity during the merge stage 0.00125 0.0-1.0
pca enable/disable normalizing the mesh before applying the convex decomposition 0 0-1
mode 0: voxel-based approximate convex decomposition, 1: tetrahedron-based approximate convex decomposition 0 0-1
maxNumVerticesPerCH controls the maximum number of triangles per convex-hull 64 4-1024
minVolumePerCH controls the adaptive sampling of the generated convex-hulls 0.0001 0.0-0.01

8 comments:

  1. Hey, Mr.Mamou. Can you make a preview or something to figure out differences from these parameters? Ultimately, I want to generate exact convex hulls instead approximated. If you reply me some preset of parameters, it can help other people who want to use your library! Thanks your efforts!

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  2. Hi, V-HACD is not meant to be an exact convex decomposition (ECD° library. To get something close to ECD, try to run with concavity=0

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  3. Thanks for reply. I tried that param but got similar result. If you know about any ECD library, please let me know. I had seen a bunny model that is covered with ECD. https://v-hacd.googlecode.com/git/snapshots/ecdvsacd.png You mean it was not generated from HACD or V-HACD, isn't it? Then how do you generate it?

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  4. The ECD decomposition was not generated by HACD or V-HACD. Try to increase the depth parameter. If you still have issues, please, send me the mesh by email.

    For an example of ECD algorithms, have a look at https://www.cs.princeton.edu/~chazelle/pubs/PhD.pdf

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  5. This comment has been removed by the author.

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  6. I've been really happy with this library! Thanks for making it available.

    I'd appreciate some more details about these parameters. For example, from the description, it is unclear if I should increase or decrease ConvexHullDownsampling to improve the quality of the results.

    I'd also recommend making it clear that gamma is very closely related to the concavity parameter. If you set the concavity very low but don't set gamma to match then the merge phase will mess everything up. Maybe it would be good to alter gamma so that it is a multiplier on concavity rather than a flat value. That would make it harder to mess up.

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  7. Could you please update your library? It is broken with blender for a long time now.

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