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> From: david.gobbi@gmail.com<BR>> Date: Wed, 27 Oct 2010 10:41:16 -0600<BR>> Subject: Re: [vtkusers] some questions about example Imagereslicing.cxx<BR>> To: juanxiaoyan@hotmail.com<BR>> CC: vtkusers@vtk.org<BR>> <BR>> 2010/10/26 ÏþÑå öÁÏþÑå <juanxiaoyan@hotmail.com>:<BR>> > i find the value of SetDataSpacing is not used when read the 2D CT images<BR>> > using vtkImageReader2, but i want to read 2D CT images as 3D according to<BR>> > value of SetDataSpacing in order to extract a interpolated slice in desired<BR>> > orientation. i wonder it can be implemented? i will appreciate any answer<BR>> > from you. thank you.<BR>> ><BR>> > some program of the example is as follows:<BR>> > vtkImageReader2 *reader = vtkImageReader2::New();<BR>> > reader->SetFilePrefix(argv[1]);<BR>> > reader->SetDataExtent(0, 63, 0, 63, 1, 93);<BR>> > reader->SetDataSpacing(3.2, 3.2, 1.5);<BR>> > reader->SetDataOrigin(0.0, 0.0, 0.0);<BR>> > reader->SetDataScalarTypeToUnsignedShort();<BR>> > reader->UpdateWholeExtent();<BR>> <BR>> The image reader cannot do any reslicing. The SetDataSpacing() method<BR>> tells VTK that the pixels in the file are 3.2mm by 3.2mm and that the<BR>> slices are 1.5mm apart, because VTK needs this information in order to<BR>> correctly render the data. To reslice the data, you must add a<BR>> vtkImageReslice filter or a vtkImageResample filter after the reader.<BR>> <BR>> I might have misunderstood your question, but I hope that my answer is helpful.<BR>> <BR>> David<BR>
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thanks David! <BR>
Because i want to get the resliced data extracted using vtkImageReslice in order to write the display program by myself. so i have another questions.<BR>
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1) VTK don't needs SetDataSpacing() method before rendering the data, so do the image reader method? <BR>
2) According to the below program, if 1) is true, i can understand why the size of the data of sagittalData is 64¡Á93 instead of 64¡Á3.2¡Á93¡Á1.5. and it is the true that the sagittalData is extracted from CT images directly without considering the DataSpacing , but it is clear that extracted reslice is bad, because the CT images are not interpolated according to the value of SetDataSpacing().<BR>
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////////////////////////////////////////////////////////// Set the slice oobliquerientation//////////////////////////////////////////////////// <BR> vtkMatrix4x4 *resliceAxesSagittal = vtkMatrix4x4::New();<BR> resliceAxesSagittal->DeepCopy(sagittalElements);<BR> // Extract a slice in the desired orientation<BR> vtkImageReslice *resliceSagittal = vtkImageReslice::New();<BR> resliceSagittal->SetInputConnection(v16->GetOutputPort());<BR> resliceSagittal->SetOutputDimensionality(2);<BR> resliceSagittal->SetResliceAxes(resliceAxesSagittal);<BR> resliceSagittal->InterpolateOn();<BR> //resliceSagittal->SetInterpolationModeToLinear();<BR> resliceSagittal->Update();<BR> ////////////////////////////////////////extract the data of sagittal////////////////////////////////////////////////////////<BR> if(resliceSagittal->GetOutput()->GetScalarPointer()==NULL){<BR> resliceSagittal->GetOutput()->AllocateScalars();<BR> }<BR> unsigned short *ptrdb=(unsigned short *)resliceSagittal->GetOutput()->GetScalarPointer();<BR> memcpy(sagittalData,ptrdb,64*93*sizeof(unsigned short));<BR><BR> </body>
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