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100 lines
3.9 KiB
100 lines
3.9 KiB
/*=========================================================================
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Program: Visualization Toolkit
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Module: $RCSfile: vtkLinkEdgels.h,v $
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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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// .NAME vtkLinkEdgels - links edgels together to form digital curves.
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// .SECTION Description
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// vtkLinkEdgels links edgels into digital curves which are then stored
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// as polylines. The algorithm works one pixel at a time only looking at
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// its immediate neighbors. There is a GradientThreshold that can be set
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// that eliminates any pixels with a smaller gradient value. This can
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// be used as the lower threshold of a two value edgel thresholding.
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//
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// For the remaining edgels, links are first tried for the four
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// connected neighbors. A successful neighbor will satisfy three
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// tests. First both edgels must be above the gradient
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// threshold. Second, the difference between the orientation between
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// the two edgels (Alpha) and each edgels orientation (Phi) must be
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// less than LinkThreshold. Third, the difference between the two
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// edgels Phi values must be less than PhiThreshold.
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// The most successful link is selected. The measure is simply the
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// sum of the three angle differences (actually stored as the sum of
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// the cosines). If none of the four connect neighbors succeeds, then
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// the eight connect neighbors are examined using the same method.
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//
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// This filter requires gradient information so you will need to use
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// a vtkImageGradient at some point prior to this filter. Typically
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// a vtkNonMaximumSuppression filter is also used. vtkThresholdEdgels
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// can be used to complete the two value edgel thresholding as used
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// in a Canny edge detector. The vtkSubpixelPositionEdgels filter
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// can also be used after this filter to adjust the edgel locations.
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// .SECTION see also
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// vtkImageData vtkImageGradient vtkImageNonMaximumSuppression
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#ifndef __vtkLinkEdgels_h
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#define __vtkLinkEdgels_h
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#include "vtkPolyDataAlgorithm.h"
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class vtkCellArray;
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class vtkDataArray;
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class vtkDoubleArray;
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class vtkPoints;
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class VTK_GRAPHICS_EXPORT vtkLinkEdgels : public vtkPolyDataAlgorithm
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{
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public:
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vtkTypeRevisionMacro(vtkLinkEdgels,vtkPolyDataAlgorithm);
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void PrintSelf(ostream& os, vtkIndent indent);
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// Description:
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// Construct instance of vtkLinkEdgels with GradientThreshold set to
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// 0.1, PhiThreshold set to 90 degrees and LinkThreshold set to 90 degrees.
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static vtkLinkEdgels *New();
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// Description:
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// Set/Get the threshold for Phi vs. Alpha link thresholding.
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vtkSetMacro(LinkThreshold,double);
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vtkGetMacro(LinkThreshold,double);
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// Description:
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// Set/get the threshold for Phi vs. Phi link thresholding.
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vtkSetMacro(PhiThreshold,double);
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vtkGetMacro(PhiThreshold,double);
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// Description:
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// Set/Get the threshold for image gradient thresholding.
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vtkSetMacro(GradientThreshold,double);
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vtkGetMacro(GradientThreshold,double);
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protected:
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vtkLinkEdgels();
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~vtkLinkEdgels() {};
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virtual int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);
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virtual int FillInputPortInformation(int port, vtkInformation *info);
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void LinkEdgels(int xdim, int ydim,double *image, vtkDataArray *inVectors,
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vtkCellArray *newLines, vtkPoints *newPts,
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vtkDoubleArray *outScalars, vtkDoubleArray *outVectors,
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int z);
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double GradientThreshold;
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double PhiThreshold;
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double LinkThreshold;
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private:
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vtkLinkEdgels(const vtkLinkEdgels&); // Not implemented.
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void operator=(const vtkLinkEdgels&); // Not implemented.
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};
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#endif
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