[Paraview] How to do volume rendering of image data?

[Steve Huntley]

According to the Paraview FAQ, Paraview supports volume rendering of 
image data.  But despite searching the Web and buying the Paraview book, 
I have not been able to find any detailed descriptions of this feature, 
let alone directions for or examples of how to do it.

I have several image stacks in png format which represent slices of 
3-dimensional objects.  I can convert an image stack into a vtk file and 
open the file in Paraview, but after that I'm at a loss.  Is it possible 
to do a volume rendering and end up with a photorealistic image of the 
reconstructed 3D object?

After opening the vtk file created from the image stack and choosing 
volume representation, all I see is a black block.  The black is 
evidently the background image area surrounding my 3D object.  I would 
like to make the black transparent and thus reveal the object, but it 
seems to me that creating a custom color scale to control opacity would 
result in color mapping and interpolation which would destroy much of 
the original color in my image.  Is there a way to declare a single 
color transparent without affecting the other colors in the image?  Is 
this a valid way to pursue volume rendering of image data?

Up to now I have been using Osirix to reconstruct 3D objects from stacks 
of slices and do photorealistic renderings of them.  But Osirix has not 
been able to handle my larger image sets without crashing, and I would 
also like to be able to script the process, as well as take advantage of 
Paraview's parallel processing capabilities.

Is it possible to accomplish something like Osirix's 3D reconstructions 
in Paraview?


Thanks,
Steve Huntley