Chris Henn (henn@neu.sgi.com)
Wed, 20 Oct 1999 18:47:47 +0200
There is no constraint whatsoever as to how many modalities you combine and
how, i.e. individual datasets do not need to be in register, they can have
different size and even different shape.
The guiding principle for multi-volume rendering is not complicated at all,
but putting all possible variations in an example makes it more convoluted
than necessary to explain how to use Volumizer.
First, you specify a global polygonalization framework to have all volume
sampling being done in register, i.e. sample in FRUSTUM space, not in OBJECT
space.
Second, you polygonize each object you want to overlay, positioning it in
whatever way that suits the application.
Then you define a processing order, i.e. how the two datasets are to be
combined, which is essentially a combination of blending or stencil
functions (e.g. for masking).
And last, you iterate over each sample plane, calling the corresponding
polygon lists for each of the individual volumes according to the specified
processing order, one at a time, in interleaved manner, every time setting
the right blending function before drawing the polygons.
Making multi-modal imaging really effective has been one of the principal
design goals for Volumizer. The provided example may be thin, however, it's
an example, not an application ...
Best regards,
Chris
-----Original Message-----
From: Mark Davey [mailto:mkd@medphys.ucl.ac.uk]
Sent: jeudi, 14. octobre 1999 9:28
To: info-volumizer
Subject: Multiple volume rendering
Hi..
I would like to say that the example code for rendering multiple volumes
is extremely limited.
Several assumptions are made, the worst being that all the volumes are
of the same size and are aligned. In order to produce a commercial
piece of software using Volumizer aimed at medical image visualisation I
would say that it is extremely important to be able to render more than
one data set at a time. There should not be the restriction of equal
size and alignment across data sets.
My question then is this. Is there any publically available code to
achieve the rendering of multiple arbitrarily sized and positioned
volumes using Volumizer. I fear that since such code was not shipped
with the API that this really is a non-trivial task, but one that is
very useful for the success of Volumizer (within a medical arena at
least)
Regards
Mark
-- From: Mark Davey Dept. of Medical Physics, UCL.TEL: +44 (0)171 915 1673. FAX: +44 (0)171 837 9279.
Institute of Laryngology and Otology, 330 Gray's Inn Road, London. WC1X 8GE.
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