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vtkGreedyTerrainDecimation Class Reference

reduce height field (represented as image) to reduced TIN More...

#include <vtkGreedyTerrainDecimation.h>

Inherits vtkPolyDataAlgorithm.

Public Types

typedef vtkPolyDataAlgorithm Superclass
 

Public Member Functions

virtual int IsA (const char *type)
 
vtkGreedyTerrainDecimationNewInstance () const
 
void PrintSelf (ostream &os, vtkIndent indent)
 
virtual void SetErrorMeasure (int)
 
virtual int GetErrorMeasure ()
 
void SetErrorMeasureToNumberOfTriangles ()
 
void SetErrorMeasureToSpecifiedReduction ()
 
void SetErrorMeasureToAbsoluteError ()
 
void SetErrorMeasureToRelativeError ()
 
virtual void SetNumberOfTriangles (vtkIdType)
 
virtual vtkIdType GetNumberOfTriangles ()
 
virtual void SetReduction (double)
 
virtual double GetReduction ()
 
virtual void SetAbsoluteError (double)
 
virtual double GetAbsoluteError ()
 
virtual void SetRelativeError (double)
 
virtual double GetRelativeError ()
 
virtual void SetBoundaryVertexDeletion (int)
 
virtual int GetBoundaryVertexDeletion ()
 
virtual void BoundaryVertexDeletionOn ()
 
virtual void BoundaryVertexDeletionOff ()
 
virtual void SetComputeNormals (int)
 
virtual int GetComputeNormals ()
 
virtual void ComputeNormalsOn ()
 
virtual void ComputeNormalsOff ()
 

Static Public Member Functions

static int IsTypeOf (const char *type)
 
static vtkGreedyTerrainDecimationSafeDownCast (vtkObjectBase *o)
 
static vtkGreedyTerrainDecimationNew ()
 

Protected Member Functions

virtual vtkObjectBase * NewInstanceInternal () const
 
 vtkGreedyTerrainDecimation ()
 
 ~vtkGreedyTerrainDecimation ()
 
virtual int RequestData (vtkInformation *, vtkInformationVector **, vtkInformationVector *)
 
virtual int FillInputPortInformation (int port, vtkInformation *info)
 
void ComputePointNormal (int i, int j, float n[3])
 
void EstimateOutputSize (const vtkIdType numInputPts, vtkIdType &numPts, vtkIdType &numTris)
 
virtual int SatisfiesErrorMeasure (double error)
 
void InsertBoundaryVertices ()
 
vtkIdType AddPointToTriangulation (vtkIdType inputPtId)
 
vtkIdType InsertNextPoint (vtkIdType inputPtId, double x[3])
 
double * GetPoint (vtkIdType id)
 
void GetPoint (vtkIdType id, double x[3])
 
void GetTerrainPoint (int i, int j, double x[3])
 
void ComputeImageCoordinates (vtkIdType inputPtId, int ij[2])
 
int InCircle (double x[3], double x1[3], double x2[3], double x3[3])
 
vtkIdType FindTriangle (double x[3], vtkIdType ptIds[3], vtkIdType tri, double tol, vtkIdType nei[3], vtkIdList *neighbors, int &status)
 
void CheckEdge (vtkIdType ptId, double x[3], vtkIdType p1, vtkIdType p2, vtkIdType tri, int depth)
 
void UpdateTriangles (vtkIdType meshPtId)
 
void UpdateTriangle (vtkIdType triId, vtkIdType p1, vtkIdType p2, vtkIdType p3)
 
void UpdateTriangle (vtkIdType triId, int ij1[2], int ij2[2], int ij3[2], double h[4])
 
int CharacterizeTriangle (int ij1[2], int ij2[2], int ij[3], int *&min, int *&max, int *&midL, int *&midR, int *&mid, int mid2[2], double h[3], double &hMin, double &hMax, double &hL, double &hR)
 

Protected Attributes

int ComputeNormals
 
vtkFloatArray * Normals
 
int ErrorMeasure
 
vtkIdType NumberOfTriangles
 
double Reduction
 
double AbsoluteError
 
double RelativeError
 
int BoundaryVertexDeletion
 
vtkPolyData * Mesh
 
vtkPointData * InputPD
 
vtkPointData * OutputPD
 
vtkDoubleArray * Points
 
vtkDataArray * Heights
 
vtkIdType CurrentPointId
 
double Tolerance
 
vtkIdList * Neighbors
 
int Dimensions [3]
 
double Origin [3]
 
double Spacing [3]
 
vtkIdType MaximumNumberOfTriangles
 
double Length
 
vtkPriorityQueue * TerrainError
 
vtkGreedyTerrainDecimationTerrainInfoType * TerrainInfo
 
vtkGreedyTerrainDecimationPointInfoType * PointInfo
 

Detailed Description

reduce height field (represented as image) to reduced TIN

vtkGreedyTerrainDecimation approximates a height field with a triangle mesh (triangulated irregular network - TIN) using a greedy insertion algorithm similar to that described by Garland and Heckbert in their paper "Fast Polygonal Approximations of Terrain and Height Fields" (Technical Report CMU-CS-95-181). The input to the filter is a height field (represented by a image whose scalar values are height) and the output of the filter is polygonal data consisting of triangles. The number of triangles in the output is reduced in number as compared to a naive tessellation of the input height field. This filter copies point data from the input to the output for those points present in the output.

An brief description of the algorithm is as follows. The algorithm uses a top-down decimation approach that initially represents the height field with two triangles (whose vertices are at the four corners of the image). These two triangles form a Delaunay triangulation. In an iterative fashion, the point in the image with the greatest error (as compared to the original height field) is injected into the triangulation. (Note that the single point with the greatest error per triangle is identified and placed into a priority queue. As the triangulation is modified, the errors from the deleted triangles are removed from the queue, error values from the new triangles are added.) The point whose error is at the top of the queue is added to the triangulaion modifying it using the standard incremental Delaunay point insertion (see vtkDelaunay2D) algorithm. Points are repeatedly inserted until the appropriate (user-specified) error criterion is met.

To use this filter, set the input and specify the error measure to be used. The error measure options are 1) the absolute number of triangles to be produced; 2) a fractional reduction of the mesh (numTris/maxTris) where maxTris is the largest possible number of triangles 2*(dims[0]-1)*(dims[1]-1); 3) an absolute measure on error (maximum difference in height field to reduced TIN); and 4) relative error (the absolute error is normalized by the diagonal of the bounding box of the height field).

Warning
This algorithm requires the entire input dataset to be in memory, hence it may not work for extremely large images. Invoking BoundaryVertexDeletionOff will allow you to stitch together images with matching boundaries.
The input height image is assumed to be positioned in the x-y plane so the scalar value is the z-coordinate, height value.
See Also
vtkDecimatePro vtkQuadricDecimation vtkQuadricClustering
Tests:
vtkGreedyTerrainDecimation (Tests)

Definition at line 91 of file vtkGreedyTerrainDecimation.h.

Member Typedef Documentation

typedef vtkPolyDataAlgorithm vtkGreedyTerrainDecimation::Superclass

Definition at line 94 of file vtkGreedyTerrainDecimation.h.

Constructor & Destructor Documentation

vtkGreedyTerrainDecimation::vtkGreedyTerrainDecimation ( )
protected
vtkGreedyTerrainDecimation::~vtkGreedyTerrainDecimation ( )
protected

Member Function Documentation

static int vtkGreedyTerrainDecimation::IsTypeOf ( const char *  type)
static
virtual int vtkGreedyTerrainDecimation::IsA ( const char *  type)
virtual
static vtkGreedyTerrainDecimation* vtkGreedyTerrainDecimation::SafeDownCast ( vtkObjectBase *  o)
static
virtual vtkObjectBase* vtkGreedyTerrainDecimation::NewInstanceInternal ( ) const
protectedvirtual
vtkGreedyTerrainDecimation* vtkGreedyTerrainDecimation::NewInstance ( ) const
void vtkGreedyTerrainDecimation::PrintSelf ( ostream &  os,
vtkIndent  indent 
)
static vtkGreedyTerrainDecimation* vtkGreedyTerrainDecimation::New ( )
static

Instantiate the class.

virtual void vtkGreedyTerrainDecimation::SetErrorMeasure ( int  )
virtual

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

virtual int vtkGreedyTerrainDecimation::GetErrorMeasure ( )
virtual

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

void vtkGreedyTerrainDecimation::SetErrorMeasureToNumberOfTriangles ( )
inline

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

Definition at line 108 of file vtkGreedyTerrainDecimation.h.

void vtkGreedyTerrainDecimation::SetErrorMeasureToSpecifiedReduction ( )
inline

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

Definition at line 110 of file vtkGreedyTerrainDecimation.h.

void vtkGreedyTerrainDecimation::SetErrorMeasureToAbsoluteError ( )
inline

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

Definition at line 112 of file vtkGreedyTerrainDecimation.h.

void vtkGreedyTerrainDecimation::SetErrorMeasureToRelativeError ( )
inline

Specify how to terminate the algorithm: either as an absolute number of triangles, a relative number of triangles (normalized by the full resolution mesh), an absolute error (in the height field), or relative error (normalized by the length of the diagonal of the image).

Definition at line 114 of file vtkGreedyTerrainDecimation.h.

virtual void vtkGreedyTerrainDecimation::SetNumberOfTriangles ( vtkIdType  )
virtual

Specify the number of triangles to produce on output. (It is a good idea to make sure this is less than a tessellated mesh at full resolution.) You need to set this value only when the error measure is set to NumberOfTriangles.

virtual vtkIdType vtkGreedyTerrainDecimation::GetNumberOfTriangles ( )
virtual

Specify the number of triangles to produce on output. (It is a good idea to make sure this is less than a tessellated mesh at full resolution.) You need to set this value only when the error measure is set to NumberOfTriangles.

virtual void vtkGreedyTerrainDecimation::SetReduction ( double  )
virtual

Specify the reduction of the mesh (represented as a fraction). Note that a value of 0.10 means a 10% reduction. You need to set this value only when the error measure is set to SpecifiedReduction.

virtual double vtkGreedyTerrainDecimation::GetReduction ( )
virtual

Specify the reduction of the mesh (represented as a fraction). Note that a value of 0.10 means a 10% reduction. You need to set this value only when the error measure is set to SpecifiedReduction.

virtual void vtkGreedyTerrainDecimation::SetAbsoluteError ( double  )
virtual

Specify the absolute error of the mesh; that is, the error in height between the decimated mesh and the original height field. You need to set this value only when the error measure is set to AbsoluteError.

virtual double vtkGreedyTerrainDecimation::GetAbsoluteError ( )
virtual

Specify the absolute error of the mesh; that is, the error in height between the decimated mesh and the original height field. You need to set this value only when the error measure is set to AbsoluteError.

virtual void vtkGreedyTerrainDecimation::SetRelativeError ( double  )
virtual

Specify the relative error of the mesh; that is, the error in height between the decimated mesh and the original height field normalized by the diagonal of the image. You need to set this value only when the error measure is set to RelativeError.

virtual double vtkGreedyTerrainDecimation::GetRelativeError ( )
virtual

Specify the relative error of the mesh; that is, the error in height between the decimated mesh and the original height field normalized by the diagonal of the image. You need to set this value only when the error measure is set to RelativeError.

virtual void vtkGreedyTerrainDecimation::SetBoundaryVertexDeletion ( int  )
virtual

Turn on/off the deletion of vertices on the boundary of a mesh. This may limit the maximum reduction that may be achieved.

virtual int vtkGreedyTerrainDecimation::GetBoundaryVertexDeletion ( )
virtual

Turn on/off the deletion of vertices on the boundary of a mesh. This may limit the maximum reduction that may be achieved.

virtual void vtkGreedyTerrainDecimation::BoundaryVertexDeletionOn ( )
virtual

Turn on/off the deletion of vertices on the boundary of a mesh. This may limit the maximum reduction that may be achieved.

virtual void vtkGreedyTerrainDecimation::BoundaryVertexDeletionOff ( )
virtual

Turn on/off the deletion of vertices on the boundary of a mesh. This may limit the maximum reduction that may be achieved.

virtual void vtkGreedyTerrainDecimation::SetComputeNormals ( int  )
virtual

Compute normals based on the input image. Off by default.

virtual int vtkGreedyTerrainDecimation::GetComputeNormals ( )
virtual

Compute normals based on the input image. Off by default.

virtual void vtkGreedyTerrainDecimation::ComputeNormalsOn ( )
virtual

Compute normals based on the input image. Off by default.

virtual void vtkGreedyTerrainDecimation::ComputeNormalsOff ( )
virtual

Compute normals based on the input image. Off by default.

virtual int vtkGreedyTerrainDecimation::RequestData ( vtkInformation *  ,
vtkInformationVector **  ,
vtkInformationVector *   
)
protectedvirtual
virtual int vtkGreedyTerrainDecimation::FillInputPortInformation ( int  port,
vtkInformation *  info 
)
protectedvirtual
void vtkGreedyTerrainDecimation::ComputePointNormal ( int  i,
int  j,
float  n[3] 
)
protected
void vtkGreedyTerrainDecimation::EstimateOutputSize ( const vtkIdType  numInputPts,
vtkIdType &  numPts,
vtkIdType &  numTris 
)
protected
virtual int vtkGreedyTerrainDecimation::SatisfiesErrorMeasure ( double  error)
protectedvirtual
void vtkGreedyTerrainDecimation::InsertBoundaryVertices ( )
protected
vtkIdType vtkGreedyTerrainDecimation::AddPointToTriangulation ( vtkIdType  inputPtId)
protected
vtkIdType vtkGreedyTerrainDecimation::InsertNextPoint ( vtkIdType  inputPtId,
double  x[3] 
)
protected
double* vtkGreedyTerrainDecimation::GetPoint ( vtkIdType  id)
protected
void vtkGreedyTerrainDecimation::GetPoint ( vtkIdType  id,
double  x[3] 
)
protected
void vtkGreedyTerrainDecimation::GetTerrainPoint ( int  i,
int  j,
double  x[3] 
)
protected
void vtkGreedyTerrainDecimation::ComputeImageCoordinates ( vtkIdType  inputPtId,
int  ij[2] 
)
protected
int vtkGreedyTerrainDecimation::InCircle ( double  x[3],
double  x1[3],
double  x2[3],
double  x3[3] 
)
protected
vtkIdType vtkGreedyTerrainDecimation::FindTriangle ( double  x[3],
vtkIdType  ptIds[3],
vtkIdType  tri,
double  tol,
vtkIdType  nei[3],
vtkIdList *  neighbors,
int &  status 
)
protected
void vtkGreedyTerrainDecimation::CheckEdge ( vtkIdType  ptId,
double  x[3],
vtkIdType  p1,
vtkIdType  p2,
vtkIdType  tri,
int  depth 
)
protected
void vtkGreedyTerrainDecimation::UpdateTriangles ( vtkIdType  meshPtId)
protected
void vtkGreedyTerrainDecimation::UpdateTriangle ( vtkIdType  triId,
vtkIdType  p1,
vtkIdType  p2,
vtkIdType  p3 
)
protected
void vtkGreedyTerrainDecimation::UpdateTriangle ( vtkIdType  triId,
int  ij1[2],
int  ij2[2],
int  ij3[2],
double  h[4] 
)
protected
int vtkGreedyTerrainDecimation::CharacterizeTriangle ( int  ij1[2],
int  ij2[2],
int  ij[3],
int *&  min,
int *&  max,
int *&  midL,
int *&  midR,
int *&  mid,
int  mid2[2],
double  h[3],
double &  hMin,
double &  hMax,
double &  hL,
double &  hR 
)
protected

Member Data Documentation

int vtkGreedyTerrainDecimation::ComputeNormals
protected

Definition at line 175 of file vtkGreedyTerrainDecimation.h.

vtkFloatArray* vtkGreedyTerrainDecimation::Normals
protected

Definition at line 176 of file vtkGreedyTerrainDecimation.h.

int vtkGreedyTerrainDecimation::ErrorMeasure
protected

Definition at line 180 of file vtkGreedyTerrainDecimation.h.

vtkIdType vtkGreedyTerrainDecimation::NumberOfTriangles
protected

Definition at line 181 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Reduction
protected

Definition at line 182 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::AbsoluteError
protected

Definition at line 183 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::RelativeError
protected

Definition at line 184 of file vtkGreedyTerrainDecimation.h.

int vtkGreedyTerrainDecimation::BoundaryVertexDeletion
protected

Definition at line 185 of file vtkGreedyTerrainDecimation.h.

vtkPolyData* vtkGreedyTerrainDecimation::Mesh
protected

Definition at line 188 of file vtkGreedyTerrainDecimation.h.

vtkPointData* vtkGreedyTerrainDecimation::InputPD
protected

Definition at line 189 of file vtkGreedyTerrainDecimation.h.

vtkPointData* vtkGreedyTerrainDecimation::OutputPD
protected

Definition at line 190 of file vtkGreedyTerrainDecimation.h.

vtkDoubleArray* vtkGreedyTerrainDecimation::Points
protected

Definition at line 191 of file vtkGreedyTerrainDecimation.h.

vtkDataArray* vtkGreedyTerrainDecimation::Heights
protected

Definition at line 192 of file vtkGreedyTerrainDecimation.h.

vtkIdType vtkGreedyTerrainDecimation::CurrentPointId
protected

Definition at line 193 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Tolerance
protected

Definition at line 194 of file vtkGreedyTerrainDecimation.h.

vtkIdList* vtkGreedyTerrainDecimation::Neighbors
protected

Definition at line 195 of file vtkGreedyTerrainDecimation.h.

int vtkGreedyTerrainDecimation::Dimensions[3]
protected

Definition at line 196 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Origin[3]
protected

Definition at line 197 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Spacing[3]
protected

Definition at line 198 of file vtkGreedyTerrainDecimation.h.

vtkIdType vtkGreedyTerrainDecimation::MaximumNumberOfTriangles
protected

Definition at line 199 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Length
protected

Definition at line 200 of file vtkGreedyTerrainDecimation.h.

vtkPriorityQueue* vtkGreedyTerrainDecimation::TerrainError
protected

Definition at line 203 of file vtkGreedyTerrainDecimation.h.

vtkGreedyTerrainDecimationTerrainInfoType* vtkGreedyTerrainDecimation::TerrainInfo
protected

Definition at line 204 of file vtkGreedyTerrainDecimation.h.

vtkGreedyTerrainDecimationPointInfoType* vtkGreedyTerrainDecimation::PointInfo
protected

Definition at line 205 of file vtkGreedyTerrainDecimation.h.


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