1. SmartBoxes for Interactive Urban Reconstruction Liangliang Nan 1, Andrei Sharf 1, Hao Zhang 2, Daniel Cohen-Or 3, Baoquan Chen 1 1 Shenzhen Institutes of Advanced Technology (SIAT), China 2 Simon Fraser University, Canada 3 University of Tel Aviv, Israel

2. Virtual BerlinVirtual Philadelphia 3D Cities

3. Acquisition of Urban Environments Cameras/videos Remote Sensing Systems 3D Digital City Auto-mounted LIDAR Airborne LIDAR

4. 3D LiDAR scanner Street-level 60km/h 180 pitch [100-300m] range 100K points/second 5cm XY accuracy

5. Outdoor Urban Scanning

7. Imperfect Scans - Occlusions Point cloud contains holes due to various occlusions (shadows)

8. Imperfect Scans – Angle & Range Oblique scanning angle Laser energy attenuation on range

9. Urban Building Characteristics Repetitions, intra symmetry and regularity Axis-aligned basic primitives Dominant planes

10. SmartBoxes Box-up and Smart!

11. SmartBoxes Box prior shape fitting Smart context awareness Both Context Data

12. Live Demo

13. 9

14. Related Work Procedural modeling of buildings and facades [Wonka2003;Muller2007] Automatic 3D reconstruction from 2D images [Zisserman2002;Xiao2009;Furukawa2009] Interactive modeling of architectural structures [Debevec1996;Schindler2003; Xiao2008;Sinha2008;Jiang2009] Primitive fitting to data [Gal2007; Schnabel 2009]

15. Preprocessing Automatic detection of planes and edges assuming dominant orthogonal axes –RANSAC planes –Line sweep edges

16. Snapping a Box 2D rubber band ROI Collect planes, edges, corners Find the best fitting box using data fitting force D(B,P)

17. Data fitting D(B,P) snap FacetEdge Data fitting force Data quality ( Confidence + Density ) Distance

18. Grouping Simple SmartBox Compound SmartBox Align to remove gaps and intersections –cluster and align close to co-linear edges

19. Drag-and-drop context C(B i-1, B i ) The context of B i B i-1 B i-2 B i-3 IntervalAlignmentScale Context BiBi

20. Drag-and-drop context C(B i-1, B i ) The context of B i –Interval term B i-1 B i-2 B i-3 BiBi

21. Drag-and-drop context C(B i-1, B i ) The context of B i –Alignment term BiBi B i-1 B i-2 B i-3

22. BiBi Drag-and-drop context C(B i-1, B i ) The context of B i –Scale term BiBi B i-1 B i-2 B i-3

23. Discrete objective minimization Find linear transformation T(excluding rotation) to minimize: Data fitting forceContextual force

24. Discrete objective minimization B i-1 B i-2 B i-3 Find linear transformation T(excluding rotation) to minimize: Data fitting forceContextual force

25. Balance between two forces

26. Emerging city of Shenzhen, China

27. Results: textured buildings

28. Manchester Civil Justice Centre (Manchester, UK) Habitat 67 (Montreal, Canada) The Crooked House (Sopot, Poland)

29. (Thank You)!