[vtkusers] vtkDecimatePro Problem

[葛为卫]

hello,everyone.

I have a problem.I appreciate someone can help me.

Here is my source code.It's very simple,read CT images and rebuild then in 3D.
You can see that I use vtkDecimatePro to decimate triangle plane.But after 
that job.I find that it costs more time.

I'm very puzzled.I take the method to speed up,but it costs more time.Can some
tell me why.

Thank everyone in advance.  Best regards.


...
...
  vtkDICOMImageReader   *reader =  vtkDICOMImageReader::New();
	reader->SetDataByteOrderToLittleEndian();
	reader->SetDirectoryName("C://data");
	reader->SetDataSpacing(3.2, 3.2, 1.5);
	reader->SetDataOrigin(0.0, 0.0, 0.0);


  vtkContourFilter *skinExtractor = vtkContourFilter::New();
    skinExtractor->SetInputConnection(reader->GetOutputPort());
    skinExtractor->SetValue(0,1500);

  vtkDecimatePro *decimatepro=vtkDecimatePro::New();
	decimatepro->SetInputConnection(skinExtractor->GetOutputPort());
	decimatepro->SetTargetReduction(0.8);


  vtkPolyDataNormals *skinNormals = vtkPolyDataNormals::New();
    skinNormals->SetInputConnection(skinExtractor->GetOutputPort());
    skinNormals->SetFeatureAngle(180);
.....
.....