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155 lines
5.1 KiB
C++
155 lines
5.1 KiB
C++
/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkCurvatures.h
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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/**
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* @class vtkCurvatures
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* @brief compute curvatures (Gauss and mean) of a Polydata object
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*
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* vtkCurvatures takes a polydata input and computes the curvature of the
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* mesh at each point. Four possible methods of computation are available :
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*
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* Gauss Curvature
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* discrete Gauss curvature (K) computation,
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* \f$K(vertex v) = 2*PI-\sum_{facet neighbs f of v} (angle_f at v)\f$
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* The contribution of every facet is for the moment weighted by \f$Area(facet)/3\f$
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* The units of Gaussian Curvature are \f$[1/m^2]\f$
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*
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* Mean Curvature
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* \f$H(vertex v) = average over edges neighbs e of H(e)\f$
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* \f$H(edge e) = length(e)*dihedral_angle(e)\f$
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* NB: dihedral_angle is the ORIENTED angle between -PI and PI,
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* this means that the surface is assumed to be orientable
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* the computation creates the orientation
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* The units of Mean Curvature are [1/m]
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*
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* Maximum (\f$k_max\f$) and Minimum (\f$k_min\f$) Principal Curvatures
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* \f$k_max = H + sqrt(H^2 - K)\f$
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* \f$k_min = H - sqrt(H^2 - K)\f$
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* Excepting spherical and planar surfaces which have equal principal curvatures,
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* the curvature at a point on a surface varies with the direction one "sets off"
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* from the point. For all directions, the curvature will pass through two extrema:
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* a minimum (\f$k_min\f$) and a maximum (\f$k_max\f$) which occur at mutually orthogonal
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* directions to each other.
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*
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* NB. The sign of the Gauss curvature is a geometric ivariant, it should be +ve
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* when the surface looks like a sphere, -ve when it looks like a saddle,
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* however, the sign of the Mean curvature is not, it depends on the
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* convention for normals - This code assumes that normals point outwards (ie
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* from the surface of a sphere outwards). If a given mesh produces curvatures
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* of opposite senses then the flag InvertMeanCurvature can be set and the
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* Curvature reported by the Mean calculation will be inverted.
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*
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* @par Thanks:
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* Philip Batchelor philipp.batchelor@kcl.ac.uk for creating and contributing
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* the class and Andrew Maclean a.maclean@acfr.usyd.edu.au for cleanups and
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* fixes. Thanks also to Goodwin Lawlor for contributing patch to calculate
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* principal curvatures
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*
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*
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*
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*/
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#ifndef vtkCurvatures_h
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#define vtkCurvatures_h
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#include "vtkFiltersGeneralModule.h" // For export macro
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#include "vtkPolyDataAlgorithm.h"
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#define VTK_CURVATURE_GAUSS 0
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#define VTK_CURVATURE_MEAN 1
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#define VTK_CURVATURE_MAXIMUM 2
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#define VTK_CURVATURE_MINIMUM 3
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class VTKFILTERSGENERAL_EXPORT vtkCurvatures : public vtkPolyDataAlgorithm
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{
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public:
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vtkTypeMacro(vtkCurvatures,vtkPolyDataAlgorithm);
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void PrintSelf(ostream& os, vtkIndent indent) VTK_OVERRIDE;
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/**
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* Construct with curvature type set to Gauss
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*/
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static vtkCurvatures *New();
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//@{
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/**
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* Set/Get Curvature type
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* VTK_CURVATURE_GAUSS: Gaussian curvature, stored as
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* DataArray "Gauss_Curvature"
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* VTK_CURVATURE_MEAN : Mean curvature, stored as
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* DataArray "Mean_Curvature"
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*/
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vtkSetMacro(CurvatureType,int);
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vtkGetMacro(CurvatureType,int);
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void SetCurvatureTypeToGaussian()
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{ this->SetCurvatureType(VTK_CURVATURE_GAUSS); }
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void SetCurvatureTypeToMean()
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{ this->SetCurvatureType(VTK_CURVATURE_MEAN); }
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void SetCurvatureTypeToMaximum()
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{ this->SetCurvatureType(VTK_CURVATURE_MAXIMUM); }
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void SetCurvatureTypeToMinimum()
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{ this->SetCurvatureType(VTK_CURVATURE_MINIMUM); }
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//@}
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//@{
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/**
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* Set/Get the flag which inverts the mean curvature calculation for
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* meshes with inward pointing normals (default false)
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*/
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vtkSetMacro(InvertMeanCurvature,int);
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vtkGetMacro(InvertMeanCurvature,int);
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vtkBooleanMacro(InvertMeanCurvature,int);
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//@}
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protected:
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vtkCurvatures();
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// Usual data generation method
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int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *) VTK_OVERRIDE;
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/**
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* discrete Gauss curvature (K) computation,
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* cf http://www-ipg.umds.ac.uk/p.batchelor/curvatures/curvatures.html
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*/
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void GetGaussCurvature(vtkPolyData *output);
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// discrete Mean curvature (H) computation,
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// cf http://www-ipg.umds.ac.uk/p.batchelor/curvatures/curvatures.html
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void GetMeanCurvature(vtkPolyData *output);
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/**
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* Maximum principal curvature \f$k_max = H + sqrt(H^2 -K)\f$
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*/
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void GetMaximumCurvature(vtkPolyData *input, vtkPolyData *output);
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/**
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* Minimum principal curvature \f$k_min = H - sqrt(H^2 -K)\f$
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*/
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void GetMinimumCurvature(vtkPolyData *input, vtkPolyData *output);
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// Vars
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int CurvatureType;
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int InvertMeanCurvature;
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private:
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vtkCurvatures(const vtkCurvatures&) VTK_DELETE_FUNCTION;
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void operator=(const vtkCurvatures&) VTK_DELETE_FUNCTION;
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};
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#endif
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