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   -> Volume 7, Issue 10


Dissertation: Wavelet-based volume rendering
 
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Lars Lippert (lars.lippert@alcatel.ch)
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PostPosted: Tue Oct 13, 1998 4:11 pm    
Subject: Dissertation: Wavelet-based volume rendering
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#12 Dissertation: Wavelet-based volume rendering

DISSERTATION: Wavelet-based volume rendering

Abstract This thesis discusses theoretical and practical improvements
to volume rendering in the context of visual data exploration and
realistic rendering of three-dimensional data sets. Despite the
increasing importance of volume rendering in the field of scientific
visualization, state-of-the-art algorithms still suffer from some
major shortcomings. Difficulties include the numerical complexity as
well as the high memory costs. This work presents a solution to these
key problems by introducing synergy-effects, provided by the
combination of the wavelet theory and new volume rendering
approaches. On basis of this combination, three concepts are presented
for the computation of global and local illumination scenarios.

First, a new physically-based volume radiosity model is derived from
the underlying transport theory model, which counts for both direct
illumination and indirect illumination due to multiple
interreflections of light. The global cube concept focuses on
hierarchical approximations of the energy transfer within a pure
volumetric environment. This concept is designed to meet the
requirements of an accurate and fast computation scheme by using
modern graphics hardware and efficient data topologies.

Next, by neglecting indirect illumination effects, a new concept of
wavelet-based image order volume rendering is derived. This technique
extends classical rendering strategies, as it allows the formulation
of a hierarchical rendering concept for locally illuminated data sets.
Further-more, global and local filtering operations of the wavelet
transformed data sets are proposed to further compress the data and to
increase the rendering speed. The analytic representation of the used
B-spline wavelets provides realistic shading effects and analytic
error bounds.

Finally, by further assuming an isotropically absorbing medium, a new
object order volume rendering approach is presented, which unifies
efficient projection methods and the hierarchical representation of
the data set in the wavelet space. This progressive rendering concept
is performed by superimposing 2D textures and provides interactive
volume visualization. The linearity of the rendering scheme allows the
implementation of a highly efficient data coding strategy that
encompasses the advantages of the wavelet transform and effective
color space transformations.

For each of these concepts, extensive error and performance analyses
of the implemented prototypes are discussed. The analyses clearly
prove the superiority of the introduced concepts.

It can be downloaded from:
ftp://ftp.inf.ethz.ch/pub/publications/dissertations/th12612.pdf

Lars Lippert
Alcatel Switzerland
Telecom Software and Services
All times are GMT + 1 Hour
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