vtkLinkEdgels Class Reference
#include <vtkLinkEdgels.h>
Inheritance diagram for vtkLinkEdgels:
[legend]Collaboration diagram for vtkLinkEdgels:
[legend]List of all members.
Detailed Description
links edgels together to form digital curves.
vtkLinkEdgels links edgels into digital curves which are then stored as polylines. The algorithm works one pixel at a time only looking at its immediate neighbors. There is a GradientThreshold that can be set that eliminates any pixels with a smaller gradient value. This can be used as the lower threshold of a two value edgel thresholding.
For the remaining edgels, links are first tried for the four connected neighbors. A successful neighbor will satisfy three tests. First both edgels must be above the gradient threshold. Second, the difference between the orientation between the two edgels (Alpha) and each edgels orientation (Phi) must be less than LinkThreshold. Third, the difference between the two edgels Phi values must be less than PhiThreshold. The most successful link is selected. The measure is simply the sum of the three angle differences (actually stored as the sum of the cosines). If none of the four connect neighbors succeeds, then the eight connect neighbors are examined using the same method.
This filter requires gradient information so you will need to use a vtkImageGradient at some point prior to this filter. Typically a vtkNonMaximumSuppression filter is also used. vtkThresholdEdgels can be used to complete the two value edgel thresholding as used in a Canny edge detector. The vtkSubpixelPositionEdgels filter can also be used after this filter to adjust the edgel locations.
- See also:
- vtkImageData vtkImageGradient vtkImageNonMaximumSuppression
- Tests:
- vtkLinkEdgels (Tests)
Definition at line 60 of file vtkLinkEdgels.h.
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| virtual void | SetLinkThreshold (double) |
| virtual double | GetLinkThreshold () |
| static vtkLinkEdgels * | New () |
Public Types |
| typedef vtkPolyDataAlgorithm | Superclass |
Public Member Functions |
| virtual const char * | GetClassName () |
| virtual int | IsA (const char *type) |
| void | PrintSelf (ostream &os, vtkIndent indent) |
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| virtual void | SetPhiThreshold (double) |
| virtual double | GetPhiThreshold () |
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| virtual void | SetGradientThreshold (double) |
| virtual double | GetGradientThreshold () |
Static Public Member Functions |
| static int | IsTypeOf (const char *type) |
| static vtkLinkEdgels * | SafeDownCast (vtkObject *o) |
Protected Member Functions |
| | vtkLinkEdgels () |
| | ~vtkLinkEdgels () |
| virtual int | RequestData (vtkInformation *, vtkInformationVector **, vtkInformationVector *) |
| virtual int | FillInputPortInformation (int port, vtkInformation *info) |
| void | LinkEdgels (int xdim, int ydim, double *image, vtkDataArray *inVectors, vtkCellArray *newLines, vtkPoints *newPts, vtkDoubleArray *outScalars, vtkDoubleArray *outVectors, int z) |
Protected Attributes |
| double | GradientThreshold |
| double | PhiThreshold |
| double | LinkThreshold |
Member Typedef Documentation
Constructor & Destructor Documentation
| vtkLinkEdgels::vtkLinkEdgels |
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| vtkLinkEdgels::~vtkLinkEdgels |
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Member Function Documentation
| virtual const char* vtkLinkEdgels::GetClassName |
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| static int vtkLinkEdgels::IsTypeOf |
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const char * |
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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 vtkLinkEdgels::IsA |
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const char * |
type |
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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. |
| void vtkLinkEdgels::PrintSelf |
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ostream & |
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vtkIndent |
indent |
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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. |
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Construct instance of vtkLinkEdgels with GradientThreshold set to 0.1, PhiThreshold set to 90 degrees and LinkThreshold set to 90 degrees.
Reimplemented from vtkPolyDataAlgorithm. |
| virtual void vtkLinkEdgels::SetLinkThreshold |
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double |
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Set/Get the threshold for Phi vs. Alpha link thresholding. |
| virtual double vtkLinkEdgels::GetLinkThreshold |
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Set/Get the threshold for Phi vs. Alpha link thresholding. |
| virtual void vtkLinkEdgels::SetPhiThreshold |
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double |
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Set/get the threshold for Phi vs. Phi link thresholding. |
| virtual double vtkLinkEdgels::GetPhiThreshold |
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Set/get the threshold for Phi vs. Phi link thresholding. |
| virtual void vtkLinkEdgels::SetGradientThreshold |
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double |
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Set/Get the threshold for image gradient thresholding. |
| virtual double vtkLinkEdgels::GetGradientThreshold |
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Set/Get the threshold for image gradient thresholding. |
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This is called by the superclass. This is the method you should override.
Reimplemented from vtkPolyDataAlgorithm. |
| virtual int vtkLinkEdgels::FillInputPortInformation |
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int |
port, |
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vtkInformation * |
info |
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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. |
Member Data Documentation
The documentation for this class was generated from the following file:
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