Is there any python code to deal with the non-popular and self-intersecting problems of 3D models

[Phbayo]

Specifically, it is to detect whether the model composed of a triangular surface has non-prevalent and self-intersecting conditions, and if so, how to remove them

[Grantim]

Hello!

There are variety of issues that may be present in mesh:

• small components
• disconnected vertices
• degenerate faces
• multiple edges
• self intersections
• holes
• (meshlib fixes non-manifoldness on load or construct, so it cannot be an issue here)

MeshLib has function to detect them and fix them

• Small components:

    # remove small components first
    area = mesh.area()
    bigComps = mm.MeshComponents.getLargeByAreaComponents(mesh,area * 0.002,None)
    mesh.deleteFaces(mesh.topology.getValidFaces() - bigComps)

• Disconnected vertices:
  

  MeshLib/test_python/test_meshBuilder.py

  Line 77 in 09b543e

  mrmesh.uniteCloseVertices(mesh,0)

• Degenerate faces:

    tolerance = mesh.computeBoundingBox().diagonal()*1e-2
    degFaces = mm.findDegenerateFaces(mesh,1e3)
    shortEdges = mm.findShortEdges(mesh,tolerance*1e-2)
    degFaces |= mm.getIncidentFaces(mesh.topology,shortEdges)
    mm.expand(mesh.topology,degFaces,3)

    dSettings = mm.DecimateSettings()
    dSettings.strategy = mm.DecimateStrategy.ShortestEdgeFirst
    dSettings.maxError = tolerance * 0.1
    dSettings.criticalTriAspectRatio = 1e3
    dSettings.tinyEdgeLength = tolerance*1e-2
    dSettings.stabilizer = mm.ResolveMeshDegenSettings().stabilizer
    dSettings.optimizeVertexPos = False
    dSettings.region = degFaces
    dSettings.maxAngleChange = mm.ResolveMeshDegenSettings().maxAngleChange
    mm.decimateMesh(mesh,dSettings)

• Multiple edges:

    multipleEdges = mm.findMultipleEdges(mesh.topology) # just find them
    # fix possible multiple edges
    mm.fixMultipleEdges(mesh)

• Self-intersections:

    # remove self-intersections
    selfIntersSettings = mm.SelfIntersections.Settings()
    selfIntersSettings.method = mm.SelfIntersections.Settings.Method.CutAndFill
    selfIntersSettings.maxExpand = 2
    selfIntersSettings.relaxIterations = 2
    mm.SelfIntersections.fix(mesh,selfIntersSettings)

• Holes:

    # fill all holes if needed
    for e in mesh.topology.findHoleRepresentiveEdges():
        mm.fillHole(mesh,e)

---

Or there is single function that fixes Holes Self-intersections Multiple edges and most degenerations (it may leave some small components).
Rebuilding by voxel conversion

    params = mm.RebuildMeshSettings()
    params.voxelSize = mm.suggestVoxelSize(mesh,5e6)
    params.fwn = mc.FastWindingNumber(mesh) # Enables usage of CUDA (mc = `from meshlib import mrcudapy as mc`)
    mesh = mm.rebuildMesh(mesh,params)

[Phbayo]

Thank you for your answer. I would like to ask you whether the mesh construction here requires the special construction of meshlib or whether I can use the construction method of other libraries for some surface data

[Grantim]

To use meshlib algorithms you need to construct Mesh object from meshlib, or read it directly from file