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85 lines
2.7 KiB
C++
85 lines
2.7 KiB
C++
/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkFiniteDifferenceGradientEstimator.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 vtkFiniteDifferenceGradientEstimator
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* @brief Use finite differences to estimate gradient.
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*
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*
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* vtkFiniteDifferenceGradientEstimator is a concrete subclass of
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* vtkEncodedGradientEstimator that uses a central differences technique to
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* estimate the gradient. The gradient at some sample location (x,y,z)
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* would be estimated by:
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*
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* nx = (f(x-dx,y,z) - f(x+dx,y,z)) / 2*dx;
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* ny = (f(x,y-dy,z) - f(x,y+dy,z)) / 2*dy;
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* nz = (f(x,y,z-dz) - f(x,y,z+dz)) / 2*dz;
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*
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* This value is normalized to determine a unit direction vector and a
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* magnitude. The normal is computed in voxel space, and
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* dx = dy = dz = SampleSpacingInVoxels. A scaling factor is applied to
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* convert this normal from voxel space to world coordinates.
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*
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* @sa
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* vtkEncodedGradientEstimator
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*/
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#ifndef vtkFiniteDifferenceGradientEstimator_h
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#define vtkFiniteDifferenceGradientEstimator_h
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#include "vtkEncodedGradientEstimator.h"
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#include "vtkRenderingVolumeModule.h" // For export macro
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class VTKRENDERINGVOLUME_EXPORT vtkFiniteDifferenceGradientEstimator
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: public vtkEncodedGradientEstimator
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{
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public:
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vtkTypeMacro(vtkFiniteDifferenceGradientEstimator, vtkEncodedGradientEstimator);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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/**
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* Construct a vtkFiniteDifferenceGradientEstimator with
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* a SampleSpacingInVoxels of 1.
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*/
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static vtkFiniteDifferenceGradientEstimator* New();
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//@{
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/**
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* Set/Get the spacing between samples for the finite differences
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* method used to compute the normal. This spacing is in voxel units.
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*/
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vtkSetMacro(SampleSpacingInVoxels, int);
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vtkGetMacro(SampleSpacingInVoxels, int);
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//@}
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// The sample spacing between samples taken for the normal estimation
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int SampleSpacingInVoxels;
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protected:
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vtkFiniteDifferenceGradientEstimator();
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~vtkFiniteDifferenceGradientEstimator() override;
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/**
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* Recompute the encoded normals and gradient magnitudes.
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*/
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void UpdateNormals(void) override;
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private:
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vtkFiniteDifferenceGradientEstimator(const vtkFiniteDifferenceGradientEstimator&) = delete;
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void operator=(const vtkFiniteDifferenceGradientEstimator&) = delete;
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};
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#endif
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