Visualizing 3D Flow with Volume Line Integral Convolution
Since its introduction four years ago, line integral convolution
[Cabral and Leedom 93] has become a very well-known and commonly used technique
for visualizing 2D flow, or flow over a surface in 3D.
However, the popularity of LIC as a tool for 3D flow visualization has
historically been somewhat limited, primarily due to the difficulties
inherent in clearly and effectively representing dense volume textures in
static, 2D images.
While at working as a staff scientist at ICASE, I investigate strategies
for more effectively using 3D LIC to portray 3D flow.
Parts of this work are described in the Visualization
'97 case study paper Interrante and Grosch. "Strategies for
Effectively Visualizing 3D Flow with Volume LIC"
(672k pdf)
and in the article Interrante and Grosch,
"Visualizing 3D Flow",
IEEE Computer Graphics and
Applications,18(4):49-53.
The
slides
from this talk describe my more recent work with 3D LIC in some greater
detail.
The images below highlight some of the results I was able to achieve. The
flow data, generated by
Dr. Chester
Grosch, represents a numerical
simulation of a hot, supersonic, laminar jet exiting into a colder, subsonic
coflow.
It is important to let the flow define the visible surface.
You can click inside the rightmost pair of images above to see mpeg animations
(about 1M each) through the slices in the 3D volume.
These side-by-side comparison images show how the use of
smoothly continuous, 3D visibility-impeding halos can clarify the
presentation of the flow information. Clicking on these images brings
up mpeg animations (about 1.6M each).
A simple modification of the
fast-LIC
algorithm by [Stalling and Hege 95]
allows the efficient computation of oriented 3D LIC images.
This work was inspired by the example of
OLIC,
an oriented LIC method developed by [Wegenkittl et al. 97].
Color remains one of the best means of conveying information about related
scalar quantities over a volume rendered flow. In the image above, color
varies from red to yellow with increasing temperature, highlighting the
effects of friction across the boundary layers in this flow.
Saturation increases with increasing streamwise vorticity across the
same set of streamlines in this image, subtly emphasizing the areas
of greatest turbulence. Both of these flows are rendered using halos.
In this image, color is used as an additional variable to represent the
magnitude of the vorticity across the flow volume.
This particular visualization conveys the pressure waves that are being
propagated down the axis of the flow. Halos are not being used.
Last updated: 1/20/98
to my home page
This work was performed in collaboration with
Dr. Chester
Grosch of Old Dominion University.
References:
Brian Cabral and Casey Leedom. "Imaging Vector Fields
Using Line Integral Convolution", Computer Graphics Proceedings, Annual
Conference Series, 1993, pp. 263-269.
Chester Grosch, J. M. Seiner, M. Y. Hussaini, and T. L.
Jackson. "Numerical Simulation of Mixing Enhancement in a Hot Supersonic
Jet", Physics of Fluids, 9(4):1125-1143, 1997.
Victoria Interrante and Chester Grosch.
"Strategies for
Effectively Visualizing 3D Flow with Volume LIC",
proceedings of Visualization '97, pp. 421-424.
Detlev Stalling and Hans-Christian Hege.
"Fast and
Resolution Independent Line Integral Convolution",
Computer Graphics Proceedings, Annual Conference Series,
1995, pp. 249-256.
Rainer Wegenkittl, Eduard Gröller and Werner Purgathofer.
"Animating Flowfields: Rendering of Oriented Line Integral Convolution",
Computer Animation '97, Geneva, Switzerland, June 1997.