generate-watertight-meshes-and-sdf-grids

Generate watertight meshes and sdf grids from degenerate, non-manifold meshes

Example pics

SDF grid	Inside View (blue = inside, red = outside	Marching Cubes output

Advantages

• Always finds inside/outside (see examples), even though the original mesh may contain intersecting triangles, no normals, tiny holes
• Very fast though CUDA implementation
• Output from Marching Cubes is garantueed to be watertight
• High resolution (grid dimension > 1000) possible
• Very important: This method generates real SDF grids - and not just TSDF grids (truncated SDF). Rendering based techniques (for SDF generation) cannot handle thin structures and often give wrong SDF values for larger volumes

Dependencies

• CUDA
• glm
• Eigen3

How-To Install

git submodule update --init --recursive
mkdir build
cd build
cmake ..
make -j 4

cd ..
cd python_scripts
pip install -r requirements.txt

How-To Run

See example script

bash example.sh

or

Generating watertight sdf grids via watershed.
Usage:
  watershed [OPTION...]

  -i, --in arg     input mesh file
  -o, --out arg    output file
  -r, --res arg    resolution (default: 0.002)
  -t, --trunc arg  surface truncation distance in voxels (default: 5)
  -p, --pad arg    outer padding for voxelgrid (default: 5)
  -v, --verbose    verbose
  -h, --help       Print usage

Checkout python_scripts/marching_cubes.py to generate meshes from .vox files

What's the output of this?

It's a binary file that contains the sdf grid information as resolution, grid dimensions, grid2world matrix, sdf values.

Have a look at src/base/Vox.h or python_scripts/Vox.py for cpp and python readers and writers.

How does it work?

It is based on a 3D watershed/floodfill algorithm, where from each corner of the grid you fill water in the grid until you reach a stationary state where the water cannot penetrate anymore the inside of the object as it is being held out by its surface. Here is an illustration: