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Specifies which segmentation algorithm to use to determine what is inside the mesh
and what is outside the mesh. By default, boundary-and-fill-and-grow voxelization
will be used.
Available algorithms are:
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0 : Perfect mesh (no voxelization).
This method works for "perfect meshes", i.e. meshes that are closed, watertight,
2-manifold and without self-intersection or interior/hidden geometry. It segments
the interior region of the mesh from the exterior using a pseudo-normal test.
It does not use voxelization. If mesh conditions are not respected, the segmentation
is likely to be wrong. This can make the segmentation process significantly longer
and prevent successful skeleton embedding.
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1 : Watertight mesh (flood fill).
This method works for "watertight meshes", i.e. meshes for which faces completely
separate the interior region of the mesh from the exterior. The mesh can have
degenerated faces, wrong face orientation, self-intersection, etc. The method
uses surface voxelization to classify as part of the interior region all voxels
intersecting with a mesh face. It then performs flood-filling from the outside,
marking all reached voxels as part of the exterior region of the model. Finally,
all unreached voxels are marked as part of the interior region. This method works
so long as the mesh is watertight, i.e. without holes up to the voxelization resolution.
Otherwise, flood-filling reaches the interior region and creates inaccurate segmentation.
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2 : Imperfect mesh (flood fill + growing).
This method works for meshes where holes could make the flood-filling step reach the
interior region of the mesh, but that have face orientation consistent enough so filling
them is possible. First, it uses surface voxelization to classify as part of the interior
region all voxels intersecting with a mesh face. It then alternates flood-filling and
growing steps. The flood-filling tries to reach all voxels from the outside so that
unreached voxels are marked as part of the interior region. The growing step uses a
relatively computation-intensive process to check for interior voxels in all neighbors
to those already identified. Any voxel identified as interior is likely to fill holes,
allowing subsequent flood-filling steps to identify more interior voxels.
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3 : Polygon soup (repair).
This method has no manifold or face orientation requirements. It reconstructs a mesh
that wraps the input mesh with a given offset (3 times the voxel size) and uses this
perfect 2-manifold mesh to segment the interior region from the exterior region of the model.
Because of the offset, it might lose some of the details and merge parts that are proximal.
However, this usually is not an issue with common models where body parts are not too close
to one another.
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99 : Direct skeleton (no embedding).
This method does not try to perform embedding. It simply returns the skeleton in its initial
pose without any attempt at embedding inside the meshes, other than placing it in the meshes
bounding box.
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