Marching Cubes

Dependencies

This node can optionally use SkImage or PyMCubes library to work. It can also work without any dependencies, but slower.

Functionality

This node uses Marching Cubes algorithm to find iso-surfaces of given scalar field, i.e. such surfaces, that for each point on a surface the scalar field has the given value. Such surfaces are also known as “implicit surfaces”.

Surfaces are generated as mesh - vertices and faces.

• Fields-> Coordinate Scalar Field

• Fields-> Voronoi Field

Inputs

This node has the following inputs:

• Field. Scalar field to find the iso-surfaces for. This input is mandatory.

• Bounds. Vertices defining the bounds for generated geometry. Only bounding box of these points is used. This input is mandatory.

  

• Value. The value of scalar field, for which the iso-surfaces should be generated. The default value is 1.0.

  

  • Fields-> Coordinate Scalar Field

  • Generator-> Box

  • Viz-> Viewer Draw

  

• SamplesX, SamplesY, SamplesZ. Number of scalar field samples to be used along X, Y and Z axes. This defines the resolution of surfaces: the higher the values, the more precise are the surfaces. Note that computation time of this node is proportional to SamplesX * SamplesY * SamplesZ, so if you increase each of these values by two times, the computation time will increase eight times. The default value is 50. These inputs are available only when Sampling parameter is set to Non-uniform.

• Samples. Number of samples of scalar field for X, Y and Z axes. This input is used instead of SamplesX, SamplesY and SamplesZ when the Sampling parameter is set to Uniform.

  

  • Fields-> Coordinate Scalar Field

  • Generator-> Box

  • Viz-> Viewer Draw

Parameters

This node has the following parameters:

• Implementation. This allows to select the algorithm implementation. The following options are possible:

  • SciKit-Image. This is available only if SciKit-Image library is available.

  • PyMCubes. This is available only if PyMCubes library is available.

  • Pure Python. This implementation is slower than other two.

  The default option depends is the first one of available, in this order.

• Sampling. The following options are available:

  • Uniform. The same number of samples will be used for X, Y and Z axes. The number of samples is provided in Samples input.

  • Non-Uniform. This allows to provide different values for X, Y and Z axes, in SamplesX, SamplesY, SamplesZ inputs, correspondingly.

    

  The default option is Uniform.

Outputs

This node has the following outputs:

• Vertices. The vertices of generated mesh.

• Faces. The faces of generated mesh. Due to the algorithm used, this output will always contain only tris.

• VertexNormals. Vertex normals. This output is only available if Implementation parameter is set to SciKit-Image.

  

  • Generator-> Line

  • Generator-> Box

  • Fields-> Coordinate Scalar Field

  • Viz-> Viewer Draw

Examples of usage

This node can be used to generate metaball-like structures:

• Generator-> NGon

• Fields-> Attractor Field

• Spacial-> Vector P Field

• Viz-> Viewer Draw

Or it is possible to generate mathematically-specified implicit surfaces. The following is known as “Saddle Tower”:

• Fields-> Scalar Field Formula

• Spacial-> Vector P Field

• Viz-> Viewer Draw

• Generator-> Box

• Fields-> Scalar Field Formula

• Number-> Number Range

• Number-> Number Range

• Number-> Map Range

• Matrix-> Matrix In

• List->List Main-> List Length

• Color-> Color In

• Viz-> Viewer Draw