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, $K(vertex v) = 2*PI-\sum_{facet neighbs f of v} (angle_f at v)$ 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 philipp.batchelor@kcl.ac.uk for creating and contributing the class and Andrew Maclean a.maclean@acfr.usyd.edu.au for cleanups and fixes. Thanks also to Goodwin Lawlor for contributing patch to calculate principal curvatures

Tests:: vtkCurvatures (Tests)

Definition at line 75 of file vtkCurvatures.h.

virtual void SetCurvatureType (int)

virtual int GetCurvatureType ()

void SetCurvatureTypeToGaussian ()

void SetCurvatureTypeToMean ()

void SetCurvatureTypeToMaximum ()

void SetCurvatureTypeToMinimum ()

static vtkCurvatures * New ()

Public Types

typedef vtkPolyDataAlgorithm Superclass

Public Member Functions

virtual const char * GetClassName ()

virtual int IsA (const char *type)

void PrintSelf (ostream &os, vtkIndent indent)

virtual void SetInvertMeanCurvature (int)

virtual int GetInvertMeanCurvature ()

virtual void InvertMeanCurvatureOn ()

virtual void InvertMeanCurvatureOff ()

Static Public Member Functions

static int IsTypeOf (const char *type)

static vtkCurvatures * SafeDownCast (vtkObject *o)

Protected Member Functions

vtkCurvatures ()

int RequestData (vtkInformation *, vtkInformationVector **, vtkInformationVector *)

void GetGaussCurvature (vtkPolyData *output)

void GetMeanCurvature (vtkPolyData *output)

void GetMaximumCurvature (vtkPolyData *input, vtkPolyData *output)

void GetMinimumCurvature (vtkPolyData *input, vtkPolyData *output)

Protected Attributes

int CurvatureType

int InvertMeanCurvature

Member Typedef Documentation

typedef vtkPolyDataAlgorithm vtkCurvatures::Superclass

Reimplemented from vtkPolyDataAlgorithm.
Definition at line 78 of file vtkCurvatures.h.

Constructor & Destructor Documentation

vtkCurvatures::vtkCurvatures ( ) [protected]

Member Function Documentation

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

Reimplemented from vtkPolyDataAlgorithm.

static 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 vtkPolyDataAlgorithm.

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 vtkPolyDataAlgorithm.

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

Reimplemented from vtkPolyDataAlgorithm.

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 vtkPolyDataAlgorithm.

static vtkCurvatures* vtkCurvatures::New ( ) [static]

Construct with curvature type set to Gauss
Reimplemented from vtkPolyDataAlgorithm.

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 90 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 92 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 94 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 96 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)

int vtkCurvatures::RequestData ( vtkInformation * ,

vtkInformationVector ** ,

vtkInformationVector *

) [protected, virtual]

This is called by the superclass. This is the method you should override.
Reimplemented from vtkPolyDataAlgorithm.

void vtkCurvatures::GetGaussCurvature ( vtkPolyData * output ) [protected]

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

void vtkCurvatures::GetMeanCurvature ( vtkPolyData * output ) [protected]

void vtkCurvatures::GetMaximumCurvature ( vtkPolyData * input,

vtkPolyData * output

) [protected]

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

void vtkCurvatures::GetMinimumCurvature ( vtkPolyData * input,

vtkPolyData * output

) [protected]

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

Member Data Documentation

int vtkCurvatures::CurvatureType [protected]

Definition at line 129 of file vtkCurvatures.h.

int vtkCurvatures::InvertMeanCurvature [protected]

Definition at line 130 of file vtkCurvatures.h.

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

dox/Graphics/vtkCurvatures.h

Generated on Mon Jan 21 23:39:06 2008 for VTK by

1.4.3-20050530


virtual void	SetCurvatureType (int)
virtual int	GetCurvatureType ()
void	SetCurvatureTypeToGaussian ()
void	SetCurvatureTypeToMean ()
void	SetCurvatureTypeToMaximum ()
void	SetCurvatureTypeToMinimum ()
static vtkCurvatures *	New ()
Public Types
typedef vtkPolyDataAlgorithm	Superclass
Public Member Functions
virtual const char *	GetClassName ()
virtual int	IsA (const char *type)
void	PrintSelf (ostream &os, vtkIndent indent)

virtual void	SetInvertMeanCurvature (int)
virtual int	GetInvertMeanCurvature ()
virtual void	InvertMeanCurvatureOn ()
virtual void	InvertMeanCurvatureOff ()
Static Public Member Functions
static int	IsTypeOf (const char *type)
static vtkCurvatures *	SafeDownCast (vtkObject *o)
Protected Member Functions
	vtkCurvatures ()
int	RequestData (vtkInformation , vtkInformationVector , vtkInformationVector )
void	GetGaussCurvature (vtkPolyData *output)
void	GetMeanCurvature (vtkPolyData *output)
void	GetMaximumCurvature (vtkPolyData input, vtkPolyData output)
void	GetMinimumCurvature (vtkPolyData input, vtkPolyData output)
Protected Attributes
int	CurvatureType
int	InvertMeanCurvature