1. An Enhanced Splatting Method Graphics and Visualization Group Department of Computer Science The University of Auckland Peter Kulka & Richard Lobb

2. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Overview Direct volume rendering High resolution splatting Results Conclusions and future work

3. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Direct volume rendering Research area within visualization Rendering of 3D volume data sets –Volume reconstruction –Calculating an illumination model Two classes of algorithms: –Ray casting –Projection methods (splatting)

4. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Volume reconstruction Problem: –Finding values between sample points

5. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Illumination models Assigning optical properties to the volume Emission-absorption model: –Volumes consist of light emitting particles –Particles also attenuate light from behind them Such a system can be described by:

6. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Ray casting Image order method Simulation of light flow along viewing rays Sharp images

7. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Splatting Object order method Projection of each volume element onto the view plane Fast

8. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Motivation Want: –Rendering speed of splatting –Image quality of ray casting Approach: –Correct errors in splatting Leads to three separate modifications Result: sharper images –We call this method high resolution splatting

9. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Modifications to standard splatting Reordering reconstruction and illumination calculations Correcting view angle distortions

10. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Modifications (cont.) Slicing the reconstruction kernel

11. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb High resolution splatting Summary:

12. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Comparison Test data set: CT scan of a human pelvis –Size: 256  256  110 sample points

13. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Results Various rendering methods (close-up): ray castingsplattinghigh resolution splatting

14. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Conclusion Three modifications to splatting: –Explicit volume reconstruction and illumination –Correcting of view angle distortions –Reconstruction along the line of projection Rendering times comparable to splatting Image quality comparable to ray casting

15. ACSC’99 - An enhanced splatting method - Peter Kulka & Richard Lobb Future work More use of texture mapping hardware Perspective views Hierarchical versions –Building octrees –Wavelet splatting