vtkCurvatures Class Reference

#include <vtkCurvatures.h>

Inheritance diagram for vtkCurvatures:

[legend]Collaboration diagram for vtkCurvatures:

[legend]List of all members.

Detailed Description

compute curvatures (Gauss and mean) of a Polydata object

vtkCurvatures takes a polydata input and computes the curvature of the mesh at each point. Four possible methods of computation are available :

Gauss Curvature discrete Gauss curvature (K) computation, K(vertex v) = 2*PI-{facet neighbs f of v} (angle_f at v) The contribution of every facet is for the moment weighted by Area(facet)/3 The units of Gaussian Curvature are [1/m^2]

Mean Curvature H(vertex v) = average over edges neighbs e of H(e) H(edge e) = length(e)*dihedral_angle(e) NB: dihedral_angle is the ORIENTED angle between -PI and PI, this means that the surface is assumed to be orientable the computation creates the orientation The units of Mean Curvature are [1/m]

Maximum (k_max) and Minimum (k_min) Principal Curvatures k_max = H + sqrt(H^2 - K) k_min = H - sqrt(H^2 - K) Excepting spherical and planar surfaces which have equal principal curvatures, the curvature at a point on a surface varies with the direction one "sets off" from the point. For all directions, the curvature will pass through two extrema: a minimum (k_min) and a maximum (k_max) which occur at mutually orthogonal directions to each other.

NB. The sign of the Gauss curvature is a geometric ivariant, it should be +ve when the surface looks like a sphere, -ve when it looks like a saddle, however, the sign of the Mean curvature is not, it depends on the convention for normals - This code assumes that normals point outwards (ie from the surface of a sphere outwards). If a given mesh produces curvatures of opposite senses then the flag InvertMeanCurvature can be set and the Curvature reported by the Mean calculation will be inverted.

Thanks:: Philip Batchelor [email protected] for creating and contributing the class and Andrew Maclean [email protected] for cleanups and fixes. Thanks also to Goodwin Lawlor for contributing patch to calculate principal curvatures

Created by:

Biddiscombe, John

CVS contributions (if > 5%):

Biddiscombe, John (72%)
Malaterre, Mathieu (18%)

CVS logs (CVSweb):

.h (/Graphics/vtkCurvatures.h)
.cxx (/Graphics/vtkCurvatures.cxx)

Tests:: vtkCurvatures (Tests)

Definition at line 86 of file vtkCurvatures.h.

Public Types

typedef vtkPolyDataToPolyDataFilter Superclass

Public Member Functions

virtual const char * GetClassName ()

virtual int IsA (const char *type)

void PrintSelf (ostream &os, vtkIndent indent)

virtual void SetCurvatureType (int)

virtual int GetCurvatureType ()

void SetCurvatureTypeToGaussian ()

void SetCurvatureTypeToMean ()

void SetCurvatureTypeToMaximum ()

void SetCurvatureTypeToMinimum ()

virtual void SetInvertMeanCurvature (int)

virtual int GetInvertMeanCurvature ()

virtual void InvertMeanCurvatureOn ()

virtual void InvertMeanCurvatureOff ()

Static Public Member Functions

int IsTypeOf (const char *type)

vtkCurvatures * SafeDownCast (vtkObject *o)

vtkCurvatures * New ()

Protected Member Functions

vtkCurvatures ()

void Execute ()

void GetGaussCurvature ()

void GetMeanCurvature ()

void GetMaximumCurvature ()

void GetMinimumCurvature ()

Protected Attributes

int CurvatureType

int InvertMeanCurvature

Member Typedef Documentation

typedef vtkPolyDataToPolyDataFilter vtkCurvatures::Superclass

Reimplemented from vtkPolyDataToPolyDataFilter.
Definition at line 89 of file vtkCurvatures.h.

Constructor & Destructor Documentation

vtkCurvatures::vtkCurvatures ( ) [protected]

Member Function Documentation

virtual const char* vtkCurvatures::GetClassName ( ) [virtual]

Reimplemented from vtkPolyDataToPolyDataFilter.

int vtkCurvatures::IsTypeOf ( const char * type ) [static]

Return 1 if this class type is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.
Reimplemented from vtkPolyDataToPolyDataFilter.

virtual int vtkCurvatures::IsA ( const char * type ) [virtual]

Return 1 if this class is the same type of (or a subclass of) the named class. Returns 0 otherwise. This method works in combination with vtkTypeRevisionMacro found in vtkSetGet.h.
Reimplemented from vtkPolyDataToPolyDataFilter.

vtkCurvatures* vtkCurvatures::SafeDownCast ( vtkObject * o ) [static]

Reimplemented from vtkPolyDataToPolyDataFilter.

void vtkCurvatures::PrintSelf ( ostream & os,

vtkIndent indent

) [virtual]

Methods invoked by print to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.
Reimplemented from vtkPolyDataToPolyDataFilter.

vtkCurvatures* vtkCurvatures::New ( ) [static]

Construct with curvature type set to Gauss
Reimplemented from vtkAlgorithm.

virtual void vtkCurvatures::SetCurvatureType ( int ) [virtual]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"

virtual int vtkCurvatures::GetCurvatureType ( ) [virtual]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"

void vtkCurvatures::SetCurvatureTypeToGaussian ( ) [inline]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"
Definition at line 101 of file vtkCurvatures.h.
References VTK_CURVATURE_GAUSS.

void vtkCurvatures::SetCurvatureTypeToMean ( ) [inline]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"
Definition at line 103 of file vtkCurvatures.h.
References VTK_CURVATURE_MEAN.

void vtkCurvatures::SetCurvatureTypeToMaximum ( ) [inline]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"
Definition at line 105 of file vtkCurvatures.h.
References VTK_CURVATURE_MAXIMUM.

void vtkCurvatures::SetCurvatureTypeToMinimum ( ) [inline]

Set/Get Curvature type VTK_CURVATURE_GAUSS: Gaussian curvature, stored as DataArray "Gauss_Curvature" VTK_CURVATURE_MEAN : Mean curvature, stored as DataArray "Mean_Curvature"
Definition at line 107 of file vtkCurvatures.h.
References VTK_CURVATURE_MINIMUM.

virtual void vtkCurvatures::SetInvertMeanCurvature ( int ) [virtual]

Set/Get the flag which inverts the mean curvature calculation for meshes with inward pointing normals (default false)

virtual int vtkCurvatures::GetInvertMeanCurvature ( ) [virtual]

Set/Get the flag which inverts the mean curvature calculation for meshes with inward pointing normals (default false)

virtual void vtkCurvatures::InvertMeanCurvatureOn ( ) [virtual]

Set/Get the flag which inverts the mean curvature calculation for meshes with inward pointing normals (default false)

virtual void vtkCurvatures::InvertMeanCurvatureOff ( ) [virtual]

Set/Get the flag which inverts the mean curvature calculation for meshes with inward pointing normals (default false)

void vtkCurvatures::Execute ( ) [protected, virtual]

This method is the old style execute method
Reimplemented from vtkSource.

void vtkCurvatures::GetGaussCurvature ( ) [protected]

discrete Gauss curvature (K) computation, cf http://www-ipg.umds.ac.uk/p.batchelor/curvatures/curvatures.html

void vtkCurvatures::GetMeanCurvature ( ) [protected]

void vtkCurvatures::GetMaximumCurvature ( ) [protected]

Maximum principal curvature k_max = H + sqrt(H^2 -K)

void vtkCurvatures::GetMinimumCurvature ( ) [protected]

Minimum principal curvature k_min = H - sqrt(H^2 -K)

Member Data Documentation

int vtkCurvatures::CurvatureType [protected]

Definition at line 140 of file vtkCurvatures.h.

int vtkCurvatures::InvertMeanCurvature [protected]

Definition at line 141 of file vtkCurvatures.h.

The documentation for this class was generated from the following file:

dox/Graphics/vtkCurvatures.h


Public Types
typedef vtkPolyDataToPolyDataFilter	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)

virtual void	SetCurvatureType (int)
virtual int	GetCurvatureType ()
void	SetCurvatureTypeToGaussian ()
void	SetCurvatureTypeToMean ()
void	SetCurvatureTypeToMaximum ()
void	SetCurvatureTypeToMinimum ()

virtual void	SetInvertMeanCurvature (int)
virtual int	GetInvertMeanCurvature ()
virtual void	InvertMeanCurvatureOn ()
virtual void	InvertMeanCurvatureOff ()
Static Public Member Functions
int	IsTypeOf (const char *type)
vtkCurvatures *	SafeDownCast (vtkObject *o)
vtkCurvatures *	New ()
Protected Member Functions
	vtkCurvatures ()
void	Execute ()
void	GetGaussCurvature ()
void	GetMeanCurvature ()
void	GetMaximumCurvature ()
void	GetMinimumCurvature ()
Protected Attributes
int	CurvatureType
int	InvertMeanCurvature