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Re: IDLgrWindow, IDLgrVolume and alpha channel (more details) [message #33794 is a reply to message #33781]

Mon, 27 January 2003 01:14

s[1]
Messages: 21
Registered: December 2002

Junior Member

Hi all,

first of all, thanks for all infos.
Here come some more details:
I am rendering two volumes, similar to the MRI + PET demo, but its two
volumes (and not two data sets in one volume) and the zbuffer of the first
is intersected with the second one.
I am rendering the two volumes to two different IDLgrBuffers.
The resulting images are then blended.

I need the alpha for two reasons:
a) To determine the contribution of each image.
b) To find the image background (o.k., that I can also do with the
zbuffer).

Another, not so important reason is that I am thinking about using the
alpha values from the image to adapt the transfer function.

I was already thinking about the "linear ramp and greyscale" solution, but
for some volumes I have to use a non-linear opacity function, so that
doesn't work.

For me, getting the 4-channel IDLgrImage Karl was talking about would be
the perfect solution.
Do I understand you correctly that there is no chance to get the alpha?
Is there a difference between using a IDLgrBuffer and IDLgrWindow for this
problem?
I think having the alpha channel during rendering and just throwing it
away without having the least chance to get it is just stupid - there
will always be someone who might make use of it...

Best regards & thanks for all help,

Sebastian

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[Message index]

		Re: IDLgrWindow, IDLgrVolume and alpha channel (more details) By: Karl Schultz on Tue, 28 January 2003 06:58
		Re: IDLgrWindow, IDLgrVolume and alpha channel (more details) By: s[1] on Mon, 27 January 2003 01:14
		Re: IDLgrWindow, IDLgrVolume and alpha channel (more details) By: Rick Towler on Thu, 30 January 2003 10:21

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