VCG Ridge Surface


The RidgeSurface filter extracts ridge or valley surfaces from point (node) scalar data. This filter operates on unstructured grid data and produces geometry output.


Extracts ridge surfaces






SmoothingRange Smoothing range for gradient computation. 1
Mode Mode for orienting the eigenvectors. Either the eigenvectors at all nodes of the cell are oriented simultaneously, or pairwise, using the eigenvectors at the nodes that share an edge.
  • cell nodes PCA
  • edge nodes PCA
Extremum Chose Ridges for the extraction of ridge surfaces and Valleys for the extraction of valley surfaces.
  • Ridges
  • Valleys
UseBisection Use bisection for detecting cell edge intersection (interpolating both, gradient and Hessian) instead of linear interpolation of directional derivatives. 0
ExcludeFLT_MAX Exclude nodes marked with FLT_MAX from extraction. 1
ExcludeLonelyNodes Exclude nodes which do not have enough neighbors (due to FLT_MAX exclusion) from extraction. 1
HessExtrEigenvalMin Minimum absolute value of second derivative across ridge (used for suppressing flat ridges). 0.0
PCAsubdomMaxPerc The second largest absolute eigenvalue must not be larger than this percentage of the largest absolute eigenvalue. 1.0
ScalarMin Minimum value of the scalar field for ridge extraction. -1e20
ScalarMax Maximum value of the scalar field for ridge extraction. 1e20
ClipScalarMin Minimum value of the scalar clipping field for clipped ridge extraction. -1e+20
ClipScalarMax Maximum value of the scalar clipping field for clipped ridge extraction. 1e20
MinSize Ridges with less than this number of triangles are suppressed. 1
FilterByCell Ridge filtering is based on cells. Otherwise it is based on cell edges (recommended). 0
CombineExceptions Instead of rejecting a triangle if a condition is violated at any corner, the violations are summed up and the the triangle is rejected if the count reaches or exceeds maxExceptions. 0
MaxExceptions A triangle is rejected if it exhibits this count of exceptions. 1
GenerateNormals Generate normals. However it is recommended to use the standard normals generation module instead. 0

Installation Instructions


Filip Sadlo

Available Files