VCG Ridge Surface
Description
The RidgeSurface filter extracts ridge or valley surfaces from point (node) scalar data. This filter operates on unstructured grid data and produces geometry output.
Details
Extracts ridge surfaces
Input
vtkUnstructuredGrid
Output
None
Parameters
Name 
Description 
Values/Default 
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.



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 

Authors
Filip Sadlo
Available Files
[BibTeX]
Acknowledgements