vtkGreedyTerrainDecimation Class Reference

#include <vtkGreedyTerrainDecimation.h>

Inheritance diagram for vtkGreedyTerrainDecimation:

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Collaboration diagram for vtkGreedyTerrainDecimation:

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List of all members.


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 90 of file vtkGreedyTerrainDecimation.h.


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 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 (vtkObject *o)
static vtkGreedyTerrainDecimationNew ()

Protected Member Functions

 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
vtkFloatArrayNormals
int ErrorMeasure
vtkIdType NumberOfTriangles
double Reduction
double AbsoluteError
double RelativeError
int BoundaryVertexDeletion
vtkPolyDataMesh
vtkPointDataInputPD
vtkPointDataOutputPD
vtkDoubleArrayPoints
vtkDataArrayHeights
vtkIdType CurrentPointId
double Tolerance
vtkIdListNeighbors
int Dimensions [3]
double Origin [3]
double Spacing [3]
vtkIdType MaximumNumberOfTriangles
double Length
vtkPriorityQueueTerrainError
vtkGreedyTerrainDecimationTerrainInfoType * TerrainInfo
vtkGreedyTerrainDecimationPointInfoType * PointInfo

Member Typedef Documentation

Reimplemented from vtkPolyDataAlgorithm.

Definition at line 93 of file vtkGreedyTerrainDecimation.h.


Constructor & Destructor Documentation

vtkGreedyTerrainDecimation::vtkGreedyTerrainDecimation (  )  [protected]

vtkGreedyTerrainDecimation::~vtkGreedyTerrainDecimation (  )  [protected]


Member Function Documentation

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

Reimplemented from vtkPolyDataAlgorithm.

static int vtkGreedyTerrainDecimation::IsTypeOf ( const char *  name  )  [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 vtkGreedyTerrainDecimation::IsA ( const char *  name  )  [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 vtkGreedyTerrainDecimation* vtkGreedyTerrainDecimation::SafeDownCast ( vtkObject o  )  [static]

Reimplemented from vtkPolyDataAlgorithm.

void vtkGreedyTerrainDecimation::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 vtkGreedyTerrainDecimation* vtkGreedyTerrainDecimation::New (  )  [static]

Instantiate the class.

Reimplemented from vtkPolyDataAlgorithm.

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 107 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 109 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 111 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 113 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 request,
vtkInformationVector **  inputVector,
vtkInformationVector outputVector 
) [protected, virtual]

This is called by the superclass. This is the method you should override.

Reimplemented from vtkPolyDataAlgorithm.

virtual int vtkGreedyTerrainDecimation::FillInputPortInformation ( int  port,
vtkInformation info 
) [protected, virtual]

Fill the input port information objects for this algorithm. This is invoked by the first call to GetInputPortInformation for each port so subclasses can specify what they can handle.

Reimplemented from vtkPolyDataAlgorithm.

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  )  [protected, virtual]

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

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double vtkGreedyTerrainDecimation::Origin[3] [protected]

Definition at line 196 of file vtkGreedyTerrainDecimation.h.

double vtkGreedyTerrainDecimation::Spacing[3] [protected]

Definition at line 197 of file vtkGreedyTerrainDecimation.h.

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vtkGreedyTerrainDecimationTerrainInfoType* vtkGreedyTerrainDecimation::TerrainInfo [protected]

Definition at line 203 of file vtkGreedyTerrainDecimation.h.

vtkGreedyTerrainDecimationPointInfoType* vtkGreedyTerrainDecimation::PointInfo [protected]

Definition at line 204 of file vtkGreedyTerrainDecimation.h.


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

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