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<TITLE>RE: [vtkusers] Advice on preprocessing before surface rendering</TITLE>
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<P><FONT SIZE=2>Hello Martin,<BR>
<BR>
You can try passing your data through a Gaussian Filter which will smooth out some<BR>
your noise:<BR>
<BR>
smImg = vtkImageGaussianSmooth()<BR>
smImg.SetDimensionality(3)<BR>
smImg.SetRadiusFactors([1.0,1.0,1.0])<BR>
smImg.SetInput(srcImg.GetOutput())<BR>
<BR>
Also you can try setting the threshold in Marching Cubes to a higher value to see<BR>
if you can remove some of the noise that way.<BR>
<BR>
If you decimate that can also alter the look of noise.<BR>
<BR>
I don't know how big your data sets are but I typically have to subsample my data which<BR>
also removes a bit of noise. But I do this step in a seperate program outside of VTK.<BR>
<BR>
There are also software packages out there that allow you to manually edit image stacks.<BR>
<BR>
Otherwise getting the trade-off between noise and data involves a lot of trial and error.<BR>
<BR>
regards,<BR>
<BR>
Henrik<BR>
<BR>
<BR>
-----Original Message-----<BR>
From: vtkusers-bounces+henrik.westerberg=crg.es@vtk.org on behalf of Martin Kavec<BR>
Sent: Tue 9/18/2007 12:43 PM<BR>
To: insight-users@itk.org; vtkusers@vtk.org<BR>
Subject: [vtkusers] Advice on preprocessing before surface rendering<BR>
<BR>
Hi,<BR>
<BR>
I have images of the MR angiography of brain, for which I would like to do<BR>
surface rendering of the vessels. The problem is that there is a high<BR>
intensity noise in the lower and central part of the images, which reduces<BR>
the quality of the rendering. Could anybody recommend me some preprocessing<BR>
steps to enhance/segment/something the vessels before the surface rendering.<BR>
To demonstrate the "quality" of the images I uploaded the montage of 4/180<BR>
slices on web:<BR>
<A HREF="http://www.uku.fi/~kavec/MRA.jpg">http://www.uku.fi/~kavec/MRA.jpg</A><BR>
<BR>
Thanks a lot for advice.<BR>
<BR>
Martin<BR>
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