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RTVR - a Flexible Java Library
for Interactive Volume Rendering
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| Abstract:
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This paper presents several distinguishing design features of
RTVR - a Java-based library for interactive volume rendering.
We describe, how the careful design of data structures, in our
case based on voxel enumeration, and an intelligent use of
lookup tables enable interactive volume rendering even on
low-end PC hardware. By assigning voxels to distinct objects within
the volume and by using an individual setup and combination of
lookup tables for each object, object-aware rendering can be
performed: different transfer functions, shading models and
compositing modes (MIP, DVR) can be mixed within a single scene,
while still providing rendering results in real-time.
While providing frame rates similar to volume visualization using
3D consumer hardware, RTVR provides much more flexibility and
extensibility due to it's pure software nature. Furthermore,
due to an efficient intermediate data representation, RTVR can
be used to provide volume viewing facilities over low-bandwidth
networks, with almost full control over rendering and visualization
mapping parameters (clipping, shading, transfer function) for
the user. This paper also addresses specific problems which arise
by the use of Java for interactive Visualization.
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| Project:
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This work has been carried out as part of the
basic research project ``interactive visualization''
at the VRVis research center in Vienna, Austria,
which is funded by an Austrian governmental research
project called Kplus.
A paper with title ``RTVR - a flexible Java library for
real-time volume rendering''
(authored by
Lukas Mroz and
Helwig Hauser)
is available as a technical report
from VRVis.
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| Animation:
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Screen capture from an interactive visualization session
with the RTVR viewer. The images have been captured at
approximately 10fps/500x400 (including the time to dump the
images to disk). As the animation is (hopefully)
displayed with 10fps, it quite well reflects the speed of
working with RTVR.
NOTE to MSIE users:
It seems that nobody at MS could imagine people making
animated GIFs with more than 10 frames. This animation has
~1000 frames, and you might notice that it gets
awfully slow using MSIE.
Solution: use Netscape for viewing this page instead, or
use some external viewer.
The animation at original resolution (~500x400)
in .avi format (MS mpeg 4 codec, 3MB)
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| Video:
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The video shows features and capabilities of RTVR:
- vis2001rtvr-small.avi, half NTSC resolution (324x243), MS mpeg4 codec, ~6MB
- vis2001rtvr-small.mpg, half NTSC resolution (324x243), mpeg1, ~8MB. Works with Quicktime player and Windows Media player.
Xanim seems to show only I-frames (drops ~90% of frames)
- vis2001rtvr-full.avi, full NTSC resolution (648x486), MS mpeg4 codec, ~15MB
- vis2001rtvr-full.mpg, full NTSC resolution (648x486), mpeg1, ~23MB
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| Applet:
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As an example for RTVR applications, a volume
viewer is available as Java applet:
- Sample data sets from a related project which can be
interactively manipulated with a RTVR based viewer.
- Interactive versions of the data shown in the figures and even more data.
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| Images:
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Note: all the medical data-sets which are
depicted on this page are courtesy of
Tiani Medgraph
and their clinical partners.
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CT scan of a human hand. Different bones and the skin surface are
rendered using various combinations of shading (phong, contour enhancement)
and compositing (DVR, MIP, summation) methods.
View the data with RTVR using
the browser's virtual machine
or using Sun's Java plugin.
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CT scan of a human head. Surface rendering of the bone.
View the data with RTVR using
the browser's virtual machine
or using Sun's Java plugin.
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CT scan of human vertebrae. surface rendering of the bone.
A non-photorealistic shading model is used to enhance contours.
Surface opacity is constant, voxel color is a combination of phong shading and
contour enhancement (based on the angle
between gradient vector and viewer).
View the data with RTVR using
the browser's virtual machine
or using Sun's Java plugin.
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CT scan of a human hand with a contrast medium injected into the
vessels. The bones and the vessels are displayed
as a phong shaded surface. The skin is displayed using using a non-photorealistic shading method which enhances the contours,
Voxel opacity of the skin corresponds to color intensity.
View the data with RTVR using
the browser's virtual machine
or using Sun's Java plugin.
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MT scan of human head. Brain (unshaded DVR) within context of surrounding tissue (summation)
the browser's virtual machine
(probably the browser will not provide suffichent memory for this data set)
or using Sun's Java plugin.
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CT scan of a human pelvis with contrast medium injected into the vessels.
A stenosis is present in one of the vessels (phong-shaded surface) close to the hip-bone (MIP).
The skin is rendered using a non-photorealistic shading method which enhances the contours.
View the data with RTVR using
the browser's virtual machine
or using Sun's Java plugin.
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Simulation results of a discrete dynamical system. Visualization of
a contact bifurcation. The contact between a chaotic attractor
(white transparent object, MIP) and the boundary of it's basin of
attraction is about to occur at the red-colored portions of the
basin boundary. One frame out of a
multi-volume
parameter series simulation.
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This page
is maintained by Lukas Mroz.
In case of questions, comments, etc., please
mailto:Mroz@VRVis.at.
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