1. Exploring Photic Extremum Lines (PELs) for 3D Surface Visualization Mario Rincón-Nigro Slides based on Xie et al Vis 2007 Presentation

2. Illustrative visualization

3. Feature Lines: Contours Pros: – Show strongest cues with model-to-background distinction Cons: – Cannot capture structure of the interior of the shape

4. Feature Lines: Suggestive Contours Pros: – Extends contours of surface. Captures concave regions Cons: – Cannot illustrate salient features in convex regions

5. Feature Lines: Ridge-Valley Lines Pros: – Captures convex and concave regions Cons: – View and light independent.

6. Photonic Extremum Lines (PELs) [Xie et al. IEEE TVCG 2007] In 2D image, an edge point is defined as a point at which the gradient magnitude assumes a maximum in the gradient direction. On 3D surfaces, the PEL is a set of points where the variation of illumination in the direction of its gradient reaches the local maximum.

7. Photonic Extremum Lines Captures inner structure Appears in both convex and concave areas View and light-dependent

8. Reported Performance [Xie et al. IEEE TVCG 2007]

9. Project Goals Implement Photum Extremum Lines [Xie et al. IEEE TVCG 2007] Implement alternative feature lines techniques for comparison purposes: – Contours – Suggestive contours – Ridges and valleys Visualize different kind of data: – Iso-surfaces from 3D scalar data – Streamtapes/streamsurfaces from 3D vector fields Evaluation is not clear: -User study -Objective metric (?) Report on findings Be interactive – Use GPU acceleration if required [Xie et al. IEEE TVCG 2007] [Chen et al CGF 2011][Hummel et al IEEE TVCG 2010]

10. Work Plan Week 1 (Nov 5): -Literature review -Prepare topic presentation Week 2 (Nov 12) & 3 (Nov 19): -PEL implementation Week 4 (Nov 26): -Implement alternative techniques for feature lines rendering: contours, suggestive contours, ridges and valleys. Week 5 (Dec 3): -Buffer week. Either: – Catch up, if delayed – Try something else (e.g. GPU acceleration), otherwise Week 6 (Dec 10): -Final presentation