[vtkusers] Advice on preprocessing before surface rendering

[Carl Henrik Westerberg]

Hello Martin,

You can try passing your data through a Gaussian Filter which will smooth out some
your noise:

smImg = vtkImageGaussianSmooth()
smImg.SetDimensionality(3)
smImg.SetRadiusFactors([1.0,1.0,1.0])
smImg.SetInput(srcImg.GetOutput())

Also you can try setting the threshold in Marching Cubes to a higher value to see
if you can remove some of the noise that way.

If you decimate that can also alter the look of noise. 

I don't know how big your data sets are but I typically have to subsample my data which
also removes a bit of noise. But I do this step in a seperate program outside of VTK.

There are also software packages out there that allow you to manually edit image stacks.

Otherwise getting the trade-off between noise and data involves a lot of trial and error.

regards,

Henrik


-----Original Message-----
From: vtkusers-bounces+henrik.westerberg=crg.es at vtk.org on behalf of Martin Kavec
Sent: Tue 9/18/2007 12:43 PM
To: insight-users at itk.org; vtkusers at vtk.org
Subject: [vtkusers] Advice on preprocessing before surface rendering
 
Hi,

I have images of the MR angiography of brain, for which I would like to do 
surface rendering of the vessels. The problem is that there is a high 
intensity noise in the lower and central part of the images, which reduces 
the quality of the rendering. Could anybody recommend me some preprocessing 
steps to enhance/segment/something  the vessels before the surface rendering. 
To demonstrate the "quality" of the images I uploaded the montage of 4/180 
slices on web:
http://www.uku.fi/~kavec/MRA.jpg

Thanks a lot for advice.

Martin
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