Oh, I see now. I don't think this approach is going to work either. First of
all, ParaView ignores the LOOKUP_TABLE defined in VTK file. It is an old
feature that is rarely used anymore (the more recent VTK files don't support
it), and it conflicts with ParaView's management of lookup
Unfortunately ParaView only has one-dimensional transfer functions
(and it doesn't handle opacity encoded in the alpha channel directly
all that well either). Please add this as a feature request.
More details for the curious:
We do one-dimensional transfer functions like so:
rgba' = f(value)
Uh, what lookup table? The data file you posted has no LOOKUP_TABLE entry.
Even if it did, the VTK format specifies that the LOOKUP_TABLE is applied to a
SCALARS entry whereas the molar.vtk file has data stored as COLOR_SCALARS.
Even if the RGB values were listed under a SCALARS entry (which
I guess there was a communication problem. It seems you're still looking
at the first file I attached in an earlier message: molar.vtk. I created
a new file with the lookup table called molar.look.vtk and attached it
to the later message that discusses lookup tables and opacity.
Moreland,
The data you sent has RGB values but no alpha values that I can see. Volume
rendering is generally not very useful if you do not have some representation
of opacity. If you were to assume a homogeneous opacity, you would get a
mostly black box with a blob of color in the middle if you looked
The alpha values are in the lookup table. Each line in the lookup table
has four values: red, green, blue, opacity. That's my understanding of
a properly formatted lookup table in a vtk file. I used:
http://www.vtk.org/VTK/img/file-formats.pdf as a reference.
All opacity values are set to
Up to now I have been working with version 3.2. I just installed
version 3.8 to see if there were any differences in behavior.
In version 3.8 I'm not allowed to do volume rendering at all. When I
try to set the Volume representation option (which resulted in display
of a black block in
Steve,
Try this:
* Create Wavelet source
* Hit Apply
* Then choose Volume from the representation combo.
That's an example of volume rendering of image data.
How let's see what's missing with your data so that it cannot be
volume rendered.
Look at the information tab. Do you see any single
Nope. ParaView is just telling you that the current operation is not supported.
Probably the best course of action is to submit a feature request to ParaView's
bug list (http://www.paraview.org/Bug) to which you can attach an example file.
I would also recommend entering the feature in
Sure. Where should I send it?
In the meantime, is there a place on the web that gives examples of how
to do volume rendering of image data as specified in the FAQ?
--Steve H.
Moreland, Kenneth wrote:
Hmm... That might be a gap in ParaView functionality. Do you have an
example data set you
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
Hi Steve,
I don't know if what you describe can be achieved in Paraview, but actually you
can do it easily with VolView [1] (another - bt not open-source - Kitware
software).
Volume rendering is a standard technique for visualising X-Ray Computed
Tomography data.
If you find out out to do this
Steve,
Your approach is correct. I don't know why you are seeing what you describe.
How are you coloring your data?
-Ken
On 7/15/10 4:37 AM, Steve Huntley step...@xhuntley.net wrote:
According to the Paraview FAQ, Paraview supports volume rendering of
image data. But despite searching the
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