Tutorial 7 Real-Time Volume Graphics

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Tutorial 7Real-Time Volume Graphics

• Klaus Engel
• Markus Hadwiger
• Christof Rezk Salama

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Real-Time Volume Graphics01 Introduction and
Theory
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Appliations Medicine
CT Human HeadVisible Human Project,US National
Library of Medicine, Maryland, USA
CT AngiographyDept. of NeuroradiologyUniversity
of Erlangen,Germany
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Applications Geology
Deformed Plasticine Model, Applied
Geology,University of Erlangen
MuschelkalkPaläontologie,Virtual Reality
Group, University of Erlangen
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Applications Archeology
Hellenic Statue of Isis3rd century B.C.ARTIS,
University of Erlangen-Nuremberg, Germany
Sotades Pygmaios Statue,5th century B.CARTIS,
University of Erlangen-Nuremberg, Germany
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Applications
Biology
Material Science, Quality Control
biological sample of the soil, CT,Virtual
Reality Group, University if Erlangen
Micro CT, Compound Material,Material Science
Department, University of Erlangen
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Applications

• Computational Science and Engineering

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Applications Computer Science

• Visualization of Pseudo Random Numbers

Entropy of Pseudo Random Numbers, Dan Kaminsky,
Doxpara Research, USA,www.doxpara.com
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Outline
Classification
Data Set
3D Rendering

• in real-time on commodity graphics hardware

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Physical Model of Radiative Transfer
Increase
true emission
in-scattering
Decrease
true absorption
out-scattering
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Ray Integration

• How do we determine the radiant energy along the
  ray?
• Physical model emission and absorption, no
  scattering

viewing ray
Absorption along the ray segment s0 - s
Initial intensity at s0
Without absorption all the initial radiant
energy would reach the point s.
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Ray Integration

• How do we determine the radiant energy along the
  ray?
• Physical model emission and absorption, no
  scattering

viewing ray
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Ray Casting

• Software Solution

Image Plane
Data Set

• Numerical Integration

• Resampling

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Numerical Solution
Extinction
Approximate Integral by Riemann sum
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Numerical Solution
Now we introduce opacity
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Numerical Solution
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Numerical Solution
can be computed recursively
Radiant energyemitted at position i
Radiant energyobserved at position i1
Absorption at position i
Radiant energyobserved at position i
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Numerical Solution
Back-to-front compositing
can be computed recursively
Front-to-back compositing
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Summary

• Emission Absorption Model
• Numerical Solutions

Back-to-front iteration
Front-to-back iteration