1. School of Computer Science and Engineering
Volume Graphics (lecture 6 : Transfer Fucntion) slides knowledgement : G. Kindlmann
Bong-Soo Sohn
School of Computer Science and Engineering
Chung-Ang University

2. Transfer Function Transfer functions make volume data visible
by mapping data values to optical properties
volume data

3. Transfer Function

4. Optical Properties
Anything that can be composited with a standard graphics operator (“over”)
Opacity: “opacity functions”
Most important
Color
Can help distinguish features
Emittance
Why don’t we use this more often?
Phong parameters (ka, kd, ks)
Index of refraction

5. Volume rendering with different transfer function
Setting transfer function is difficult, unintuitive, and slow

6. Goal Make good renderings easier to come by
Make space of TFs less confusing
Remove excess “flexibility”
Provide one or more of:
Information
Guidance
Semi-automation
Automation

7. Semi-automatic generation of TF
edges

8. Scatter plot

9. Analysis

10. Distance Map

11. Whole Process

12. Result : CT Head

13. Result

14. Multidimensional Transfer Fucntion

15. 1D vs 2D histogram

16. Volume rendering using 2D transfer function

17. Multidimensional transfer function

18. Multivariate Imaging Data

19. Interaction Tools Data Probe Clipping plane Classification Widget
Triangle
rectangle

20. Dual Domain Interaction

21. Results

22. Results

23. Results