[vtkusers] how to speed up vtkVoxelModeller?

[Lars Hegenbart]

Dear VTK-Users,

I am using vtkVoxelModeller (vtk5.0) to voxelise polygonal mesh (e.g.  
surface model made out off some ten-thousands quads). The target  
voxel dimensions are about 90 x 50 x 300 = 1.35e6.

The problem is, that is very slow. On a WinXP Pentium4, 3.4 GHz  
machine it takes days to get one surface model voxelised.

How can I possibly speed up vtkVoxelModeller?



Here comes my code:

vtkPolyData *polyOrgan = vtkPolyData::New();

polyOrgan->SetPoints(points); // points are generated before

points->Delete();

polyOrgan->SetPolys(polys); // polys are generated before

polys->Delete();

vtkCleanPolyData *polyOrganClean = vtkCleanPolyData::New();

polyOrganClean->SetInput(polyOrgan);// get rid of double definitions

vtkVoxelModeller *voxelmacher = vtkVoxelModeller::New();

voxelmacher->SetSampleDimensions(90,50,300);

voxelmacher->SetModelBounds( /* box just around the polydata */ );

voxelmacher->SetInput(polyOrganClean->GetOutput());

vtkDataSetWriter *aWriter = vtkDataSetWriter::New();

aWriter->SetFileName("afile.vtk");

aWriter->SetInputConnection(voxelmacher->GetOutputPort());



A performance check told me the following cpu-time fractions when my  
code running:

	36.7%	vtkQuad::EvaluatePosition(double*, double*, int&, double*,  
double&, double*)	
	19.4%	vtkDataArrayTemplate<double>::GetTuple(int, double*)	
	7.1%	vtkPoints::GetPoint(int, double*)	
	4.5%	vtkTriangle::ComputeNormal(double*, double*, double*, double*)	
	3.5%	vtkQuad::InterpolationFunctions(double*, double*)	
	3.4%	vtkQuad::InterpolationDerivs(double*, double*)	


Thanks in advance for any hints to speed up vtkVoxelModeller!

Best regards

Lars