1. Real-Time Volume Graphics [05] Transfer Functions

2. Classification
During Classification the user defines the „Look“ of the data.
Which parts are transparent?
Which parts have which color?

3. Absorption A (opaticity α)
Classification
During Classification the user defines the „Look“ of the data.
Which parts are transparent?
Which parts have which color?
The user defines a Transfer function.
scalar S
Emission RGB
Transfer Function
Absorption A (opaticity α)

4. Classification
Real-Time update of the transfer function necessary!!!

5. Classification

6. Pre- vs Post-Interpolative Classification
PRE-INTERPOLATIVE
POST-INTERPOLATIVE
interpolation
optical properties
optical properties
interpolation
data value
data value
Pre-interpolative classification : affecter une valeur d’couleur et opacité à chaque voxel et interpolation de ces valeurs à la rasterization
Post-interpolative : à la rasterization interpoler la densité en fonctions des valeurs de densité des pixels voisins, puis appliquer la fonction de classification à l’aide d’une texture afin d’obtenir la couleur et l’opacité interpolées.

7. Pre- vs Post-Classification
Continuous data
Discrete data
alpha value
Scalar value
Transfer Function
Transfer Function
Supersampling
Supersampling
Transfer Function
Classified data
Pre-interpolative TF
Analytical Solution
Post-interpolative TF

8. Quality: Pre- vs. Post-Classification
Comparison of image quality
Pre-Classification
Post-Classification
Same TF, same Resolution, same Sampling Rate

9. Quality
Pre-Classification
Post-Classification

10. Pre-Integrated Classification