meshToVolume skipping over small features

[Greg Hurst]

I have a mesh with tiny tunnels. I've noticed if their diameter is less than 4 times the voxel spacing, they are looked over.

This only happens for signed distance fields, and using the flag DISABLE_INTERSECTING_VOXEL_REMOVAL shows they are not skipped over but have wrong values and are then deleted.

My only workaround is to sample at a finer resolution and then downsample the grid. This however is much slower and memory intensive.

I've attached an example mesh, small_tunnel.stl, which is a tunnel of diameter 0.03. Sampling over a grid with spacing 0.01 shows the missing tunnel (in the screenshot I removed an outer wall to see inside).

  

[Ignacio Martín Ochoa]

Interesting question Greg, I would also like to know what's going on.

Sorry if it's a bit off-topic, but how did you visualize the images? Especially the "Cut open SDF" image, It looks quite nice :) 

[Greg Hurst]

I wrote a little utility to import vdb into Mathematica as a SparseArray object. I then made a Graphics3D scene with a colored Cuboid for each nonzero position.