262 lines
11 KiB
C
262 lines
11 KiB
C
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/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkBinnedDecimation.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 vtkBinnedDecimation
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* @brief reduce the number of triangles in a vtkPolyData mesh
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*
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* vtkBinnedDecimation is a filter to reduce the number of triangles in a
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* triangle mesh represented by vtkPolyData. It is similar to
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* vtkQuadricClustering in concept, although it is performance accelerated:
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* it does not use quadric error metrics to position points in the bins, plus
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* it is threaded. (See vtkQuadricClustering for more information.) It also
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* takes some short cuts in the interest of speed: it limits the binning
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* resolution to no more than 2^31 bins; and it can (optionally) reuse the input
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* points in the output (to save memory and computational costs).
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*
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* A high-level overview of the algorithm is as follows. Points are binned
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* into a regular grid subdivided in the x-y-z directions. The idea is to
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* combine all the points within each bin into a single point which is then
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* used by the output triangles. Four options are available to generate the
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* output points. If the input points are to be reused as the output points,
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* then all points in the same bin simply adopt the coordinates of one of the
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* selected points in the bin (and thus all points in the bin take on the
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* same output point id). Alternatively, if new output points are to be
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* generated, then either one point is selected; the centers of occupied bins
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* can be used as the output point coordinates; or an average position of all
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* points falling into the bin can be used to generate the bin
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* point. Finally, triangles are inserted into the output: triangles whose
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* three, binned points lie in separate bins are sent to the output, while
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* all others are discarded (i.e., triangles with two or more points in the
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* same bin are not sent to the output).
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*
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* To use this filter, specify the divisions defining the spatial subdivision
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* in the x, y, and z directions. Of course you must also specify an input
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* vtkPolyData / filter connection. Higher division levels generally produce
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* results closer to the original mesh. Note that for performance reasons
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* (i.e., related to memory), the maximum divisions in the x-y-z directions
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* is limited in such a way (i.e., proportional scaling of divisions is used)
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* so as to ensure that no more than 2^31 bins are used. Higher divisions have
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* modest impact on the overall performance of the algorithm, although the
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* resolution of the output vtkPolyData is affected significantly (i.e., many
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* more triangles may be generated).
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*
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* @warning
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* This filter can drastically affect mesh topology, i.e., topology is not
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* preserved.
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*
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* @warning
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* This filter and vtkQuadricClustering produce similar results, with
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* vtkQuadricClustering theoretically producing better results. In practice
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* however, vtkBinnedDecimation produces results that are visually close to
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* vtkQuadricClustering at speeds approaching 10-100x faster (depending on
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* the bin divisions, and how the output points are generated), and the
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* algorithm requires much less memory. Note that the API of this filter is a
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* subset of vtkQuadricClustering and can often be used interchangeably with
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* vtkQuadricClustering.
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*
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* @warning
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* Algorithm 4) BIN_CENTERS uses a very different implementation strategy
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* requiring a sort of all points. It scales better as the number of bins
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* increases.
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*
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* @warning
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* For certain types of geometry (e.g., a mostly 2D plane with jitter in the
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* normal direction), this decimator can perform badly. In this situation,
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* set the number of bins in the normal direction to one.
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*
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* @warning
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* This class has been threaded with vtkSMPTools. Using TBB or other
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* non-sequential execution type (set in the CMake variable
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* VTK_SMP_IMPLEMENTATION_TYPE) may improve performance significantly.
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*
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* @sa
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* vtkQuadricClustering vtkDecimatePro vtkDecimate vtkQuadricLODActor
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* vtkTriangleFilter
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*/
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#ifndef vtkBinnedDecimation_h
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#define vtkBinnedDecimation_h
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#include "vtkFiltersCoreModule.h" // For export macro
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#include "vtkPolyDataAlgorithm.h"
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class VTKFILTERSCORE_EXPORT vtkBinnedDecimation : public vtkPolyDataAlgorithm
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{
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public:
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///@{
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/**
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* Standard instantiation, type and print methods.
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*/
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static vtkBinnedDecimation* New();
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vtkTypeMacro(vtkBinnedDecimation, vtkPolyDataAlgorithm);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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///@}
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///@{
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/**
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* Set/Get the number of divisions along each axis for the spatial bins.
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* The number of spatial bins is NumberOfXDivisions*NumberOfYDivisions*
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* NumberOfZDivisions. The filter may choose to ignore large numbers of
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* divisions if the input has few points and AutoAdjustNumberOfDivisions is
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* enabled. Also, the maximum number of divisions is controlled so that no
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* more than 2^31 bins are created. (If bin adjustment due to the limit on
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* the number of bins is necessary, then a proportional scaling of the
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* divisions in the x-y-z directions is used.) This API has been adopted
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* to be consistent with vtkQuadricClustering.
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*/
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void SetNumberOfXDivisions(int num);
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void SetNumberOfYDivisions(int num);
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void SetNumberOfZDivisions(int num);
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vtkGetMacro(NumberOfXDivisions, int);
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vtkGetMacro(NumberOfYDivisions, int);
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vtkGetMacro(NumberOfZDivisions, int);
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void SetNumberOfDivisions(int div[3]) { this->SetNumberOfDivisions(div[0], div[1], div[2]); }
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void SetNumberOfDivisions(int div0, int div1, int div2);
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int* GetNumberOfDivisions() VTK_SIZEHINT(3);
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void GetNumberOfDivisions(int div[3]);
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///@}
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///@{
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/**
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* Enable automatic adjustment of number of divisions. If disabled, the
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* number of divisions specified by the user is always used (as long as it
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* is valid). The default is On.
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*/
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vtkSetMacro(AutoAdjustNumberOfDivisions, bool);
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vtkGetMacro(AutoAdjustNumberOfDivisions, bool);
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vtkBooleanMacro(AutoAdjustNumberOfDivisions, bool);
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///@}
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///@{
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/**
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* This is an alternative way to set up the bins. If you are trying to
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* match boundaries between pieces, then you should use these methods
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* rather than SetNumberOfDivisions(). To use these methods, specify the
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* origin and spacing of the spatial binning.
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*/
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void SetDivisionOrigin(double x, double y, double z);
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void SetDivisionOrigin(double o[3]) { this->SetDivisionOrigin(o[0], o[1], o[2]); }
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vtkGetVector3Macro(DivisionOrigin, double);
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void SetDivisionSpacing(double x, double y, double z);
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void SetDivisionSpacing(double s[3]) { this->SetDivisionSpacing(s[0], s[1], s[2]); }
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vtkGetVector3Macro(DivisionSpacing, double);
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///@}
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///@{
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/**
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* Four options exist for generating output points. 1) Pass the input
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* points through to the output; 2) select one of the input points in the bin and
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* use that; 3) generate new points at the center of bins (only center bin
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* points used by the output triangles are generated); and 4) generate new
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* points from the average of all points falling into a bin and used by
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* output triangles. Note that 1) can result in many, unused output points,
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* but tends to be fastest for small numbers of bins. This can impact
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* rendering memory usage as all points are typically pushed into the
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* graphics hardware. Options 2-4 produce only points used by the output
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* triangles but generally take longer (for small numbers of bins), with
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* speeds slowing in order from options 2 through 4. In terms of quality,
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* option 4 (BIN_AVERAGES) produces the best output; options 1) and 2)
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* produce decent output, with option 3) (BIN_CENTERS) producing a
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* voxelized-like result (which is quite useful for illustrative purposes).
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* Note that for very large numbers of bins (say number of divisions > 500^3),
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* then algorithm 4) BIN_AVERAGES scales better, i.e., is likely faster and
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* produces better results.
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*/
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enum
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{
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INPUT_POINTS = 1,
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BIN_POINTS = 2,
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BIN_CENTERS = 3,
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BIN_AVERAGES = 4
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};
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vtkSetClampMacro(PointGenerationMode, int, INPUT_POINTS, BIN_AVERAGES);
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vtkGetMacro(PointGenerationMode, int);
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void SetPointGenerationModeToUseInputPoints() { this->SetPointGenerationMode(INPUT_POINTS); }
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void SetPointGenerationModeToBinPoints() { this->SetPointGenerationMode(BIN_POINTS); }
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void SetPointGenerationModeToBinCenters() { this->SetPointGenerationMode(BIN_CENTERS); }
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void SetPointGenerationModeToBinAverages() { this->SetPointGenerationMode(BIN_AVERAGES); }
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///@}
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///@{
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/**
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* This flag directs the filter to produce output point data from the input
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* point data (on by default). If the ProducePointData is set to
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* INPUT_POINTS, point data is simply passed from input to output (since
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* the points don't change). If the point generation mode is set to
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* BIN_AVERAGES, then the average of all point data values withing a bin
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* are associated with the point generated in the bin. If the point
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* generation mode is either BIN_POINTS or BIN_CENTERS, then the point
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* data values from one of the points falling into the bin is used.
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*/
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vtkSetMacro(ProducePointData, bool);
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vtkGetMacro(ProducePointData, bool);
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vtkBooleanMacro(ProducePointData, bool);
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///@}
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///@{
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/**
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* This flag directs the filter to copy cell data from input to output.
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* This flag is off by default.
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*/
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vtkSetMacro(ProduceCellData, bool);
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vtkGetMacro(ProduceCellData, bool);
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vtkBooleanMacro(ProduceCellData, bool);
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///@}
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/**
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* Return a flag indicating whether large ids were used during
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* execution. The value of this flag is only valid after filter
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* execution. The filter may use a smaller id type unless it must use
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* vtkIdType to represent points and cell ids.
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*/
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bool GetLargeIds() { return this->LargeIds; }
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protected:
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vtkBinnedDecimation();
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~vtkBinnedDecimation() override;
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int RequestData(vtkInformation*, vtkInformationVector**, vtkInformationVector*) override;
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int FillInputPortInformation(int, vtkInformation*) override;
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int NumberOfXDivisions;
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int NumberOfYDivisions;
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int NumberOfZDivisions;
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int NumberOfDivisions[3];
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// Since there are two ways of specifying the grid, we the the flag below
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// to indicate which the user has set. When this flag is on, the bin sizes
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// are computed from the DivisionOrigin and DivisionSpacing.
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int ComputeNumberOfDivisions;
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bool AutoAdjustNumberOfDivisions;
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double DivisionOrigin[3];
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double DivisionSpacing[3];
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double Bounds[6];
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int PointGenerationMode;
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bool ProducePointData;
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bool ProduceCellData;
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bool LargeIds;
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// Helper function
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void ConfigureBinning(vtkPolyData* input, vtkIdType numPts);
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private:
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vtkBinnedDecimation(const vtkBinnedDecimation&) = delete;
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void operator=(const vtkBinnedDecimation&) = delete;
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};
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#endif
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