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75 lines
2.7 KiB
75 lines
2.7 KiB
/*=========================================================================
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Program: Visualization Toolkit
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Module: $RCSfile: vtkFiniteDifferenceGradientEstimator.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 vtkFiniteDifferenceGradientEstimator - Use finite differences to estimate gradient.
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//
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// .SECTION Description
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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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// .SECTION see also
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// vtkEncodedGradientEstimator
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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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class VTK_VOLUMERENDERING_EXPORT vtkFiniteDifferenceGradientEstimator : public vtkEncodedGradientEstimator
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{
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public:
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vtkTypeRevisionMacro(vtkFiniteDifferenceGradientEstimator,vtkEncodedGradientEstimator);
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void PrintSelf( ostream& os, vtkIndent indent );
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// Description:
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// Construct a vtkFiniteDifferenceGradientEstimator with
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// a SampleSpacingInVoxels of 1.
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static vtkFiniteDifferenceGradientEstimator *New();
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// Description:
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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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vtkSetMacro( SampleSpacingInVoxels, int );
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vtkGetMacro( SampleSpacingInVoxels, int );
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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();
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// Description:
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// Recompute the encoded normals and gradient magnitudes.
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void UpdateNormals( void );
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private:
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vtkFiniteDifferenceGradientEstimator(const vtkFiniteDifferenceGradientEstimator&); // Not implemented.
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void operator=(const vtkFiniteDifferenceGradientEstimator&); // Not implemented.
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};
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#endif
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