1. GATE-540 1 Reconstruction from Polygon Soup (GATE-540) Dr.Çağatay ÜNDEĞER Instructor Middle East Technical University, GameTechnologies & General Manager SimBT Inc. e-mail : cagatay@undeger.com Game Technologies Program – Middle East Technical University – Spring 2010 Reference: Thomas Funkhouser, Princeton University

2. GATE-540 2 Outline Reconstruction

3. GATE-540 3 Goals Develop 3D Analysis Algorithms: –Reconstruction –Segmentation –Feature Detection –Labeling –Matching –Classification –Retrielval –Recognition –Clustering

4. GATE-540 4 Goal Aim to reconstruct consistent solid geometry and boundary representations for the objects modeled by a set of polygons or line segments of polygons.

5. GATE-540 5 Problems with Input Data Model may be non-manifold (no topology): –Missing polygons –Overlapping / intersecting polygons –Unconnected polygons –Unoriented polygons –T-Junctions

6. GATE-540 6 Methods Boundary Stitching Boundary Resampling Solid Region Labeling

7. GATE-540 7 Boundary Stitching Boundary Resampling Solid Region Labeling

8. GATE-540 8 Boundary Resampling Boundary Stitching Boundary Resampling Solid Region Labeling

9. GATE-540 9 Boundary Resampling Boundary Stitching Boundary Resampling Solid Region Labeling

10. GATE-540 10 Solid Region Labeling Boundary Stitching Boundary Resampling Solid Region Labeling

11. GATE-540 11 Solid Region Labeling A Three Step Solid Region Labeling Algorithm T.M.Murali and T.A.Funkerhouser Consistent Solid and Boundary Representations from Arbitrary Polygonal Data

12. GATE-540 12 Spatial Subdivision Determine BSP and Cell Complex

13. GATE-540 13 Solid Determination Principles: –Adjacent cells sharing a transparent boundary should have the same solidity –Adjacent cells sharing an opaque boundary should have opposite solidities –Unbounded cells are not solid

14. GATE-540 14 Model Output Output a polygon for each boundary separating a solid cell from a non-solid cell (oriented away from solid)

15. GATE-540 15 Results

16. GATE-540 16 Results