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115 lines
3.9 KiB
C
115 lines
3.9 KiB
C
3 weeks ago
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/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkLinkEdgels.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 vtkLinkEdgels
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* @brief links edgels together to form digital curves.
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*
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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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*
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* @sa
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* vtkImageData vtkImageGradient vtkImageNonMaximumSuppression
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*/
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#ifndef vtkLinkEdgels_h
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#define vtkLinkEdgels_h
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#include "vtkFiltersGeneralModule.h" // For export macro
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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 VTKFILTERSGENERAL_EXPORT vtkLinkEdgels : public vtkPolyDataAlgorithm
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{
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public:
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vtkTypeMacro(vtkLinkEdgels, vtkPolyDataAlgorithm);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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/**
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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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*/
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static vtkLinkEdgels* New();
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//@{
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/**
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* Set/Get the threshold for Phi vs. Alpha link thresholding.
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*/
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vtkSetMacro(LinkThreshold, double);
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vtkGetMacro(LinkThreshold, double);
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//@}
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//@{
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/**
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* Set/get the threshold for Phi vs. Phi link thresholding.
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*/
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vtkSetMacro(PhiThreshold, double);
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vtkGetMacro(PhiThreshold, double);
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//@}
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//@{
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/**
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* Set/Get the threshold for image gradient thresholding.
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*/
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vtkSetMacro(GradientThreshold, double);
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vtkGetMacro(GradientThreshold, double);
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//@}
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protected:
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vtkLinkEdgels();
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~vtkLinkEdgels() override {}
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int RequestData(vtkInformation*, vtkInformationVector**, vtkInformationVector*) override;
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int FillInputPortInformation(int port, vtkInformation* info) override;
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void LinkEdgels(int xdim, int ydim, double* image, vtkDataArray* inVectors,
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vtkCellArray* newLines, vtkPoints* newPts, vtkDoubleArray* outScalars,
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vtkDoubleArray* outVectors, 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&) = delete;
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void operator=(const vtkLinkEdgels&) = delete;
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};
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#endif
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