This page contains images and video footage to accompany "A
Video-Based Rendering Acceleration Algorithm for Interactive
Walkthroughs" by Wilson, Manocha, Lin, Yeo, and Yeung, published
in ACM Multimedia 2000. Information about spatial video
encoding is on a different page.
Contents
The Paper
Abstract
We present a new approach for faster rendering of large
synthetic environments using video-based representations. We
decompose the large environment into cells and pre-compute
video-based impostors using MPEG compression to represent
sets of objects that are far from each cell. At runtime, we
decode the MPEG streams and use displaying algorithms that
provide nearly constant-time random access to any frame. The
resulting system has been implemented and used for an
interactive walkthrough of a model of a house with 260,000
polygons and realistic lighting and textures. It is able to
render this model at 16 frames per second on average on a
Pentium II PC with an off-the-shelf graphics card.
A copy of the paper itself is available as a
PDF file (494k). It will appear in the ACM Multimedia 2000
proceedings.
Images
These are images taken from the running system. Each one is a
thumbnail; click to get a higher-resolution version.
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This is the house model we use for our environment, seen
from overhead with the roof removed. The image on the right
has the cell grid overlaid in green.
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From here on down, the image on the left shows a scene rendered
with geometry only. The image on the right employs video-based
impostors.
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This is a typical view of the kitchen. The color
discontinuity in the image on the right is an
implementation problem, but is useful here to point out
where the impostors begin. There's a small amount of
perspective distortion in this image where objects cross
the impostor boundary.
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Another view of the kitchen. The color problem is still
there, but perspective distortion is minimized.
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This view of the kitchen shows the worst-case perspective
distortion. The viewpoint is at the very edge of a cell, as
far from the point at which the impostor was captured as
possible. A smaller cell grid or a more sophisticated
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Perspective distortion is less apparent in environments with
lots of objects, as the eye is not drawn as immediately to
the problematic areas.
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Another view of the living room.
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The color discontinuity here is due to a mismatch in the
YUV<->RGB conversions used by the MPEG encoder and decoder.
We are working to correct this.
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This particular part of the environment could also be
exploited with traditional cells-and-portals partitioning.
A better method of cell creation would take into account the
portal formed by the archway leading into the bedroom.
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System Footage
These movies contain live footage of the running walkthrough
system. All are in AVI format, encoded using Intel's Indeo
codec; MPEG versions will be provided soon.
- Movie 1: system in operation (shows differing frame rates with and without impostors)
Contacting the Authors
Snail mail:
Andy Wilson
Department of Computer Science
CB 3175, Sitterson Hall
University of North Carolina
Chapel Hill, NC 27599-3175
USA
Email: Andy's address is awilson@cs.unc.edu.
Andy Wilson
Last modified: Tue Dec 11 22:54:18 EST 2001
