GitHub

API

Quick Start - isosurface

Given 3D levelset data such as a CT scan, we can do:

using Meshing

A = rand(50,50,50) # 3D Matrix

points,faces = isosurface(A)

An iso-level is specified within the algorithm specification as follows:

using Meshing

A = rand(50,50,50) # 3D Matrix

points,faces = isosurface(A, MarchingCubes(iso=1))

Isosurface

isosurface is the common and generic API for isosurface extraction with any type of abstract vector/vertex/face type.

Meshing.isosurface — Function
isosurface(V)
isosurface(V, method::AbstractMeshingAlgorithm, X, Y, Z)

isosurface is the general interface to all isosurface extraction algorithms.

Returns: (Vector{NTuple{3, T}, }, Vector{NTuple{3, Int}})

Defaults: method must be an instance of an AbstractMeshingAlgorithm, e.g.:

  • MarchingCubes()
  • MarchingTetrahedra()

If isosurface is called without a specified algorithm, it will default to MarchingCubes.

If a subtype of AbstractArray is specified, the mesh will by default be centered at the origin between (-1,1) in each axis.

See also:

source

Meshing Algorithms

Three meshing algorithms exist:

  • MarchingCubes()
  • MarchingTetrahedra()

Each takes optional iso and eps parameters, e.g. MarchingCubes(iso=0.0,eps=1e-6).

Here iso controls the offset for the boundary detection. By default this is set to 0. eps is the detection tolerance for a voxel edge intersection.

Users must construct an algorithm type and use it as an argument to a GeometryTypes mesh call or isosurface call.

Visual Comparison: From left: Marching Cubes, Naive Surface Nets, Marching Tetrahedra

comparison

Meshing.MarchingCubes — Type
MarchingCubes(;iso=0.0)

Specifies the use of the Marching Cubes algorithm for isosurface extraction. This algorithm provides a good balance between performance and vertex count. In contrast to the other algorithms, vertices may be repeated, so mesh size may be large and it will be difficult to extract topological/connectivity information.

  • iso (default: 0.0) specifies the iso level to use for surface extraction.
source
Meshing.MarchingTetrahedra — Type
MarchingTetrahedra(;iso=0.0, eps=1e-3)

Specifies the use of the Marching Tetrahedra algorithm for isosurface extraction. This algorithm generates more faces. However, each vertex is guaranteed to not be repeated, making this algorithm useful for topological analysis.

  • iso specifies the iso level to use for surface extraction.
  • eps is the tolerence around a voxel corner to ensure manifold mesh generation.
source