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
Virtual BerlinVirtual Philadelphia 3D Cities
Acquisition of Urban Environments Cameras/videos Remote Sensing Systems 3D Digital City Auto-mounted LIDAR Airborne LIDAR
3D LiDAR scanner Street-level 60km/h 180 pitch [ m] range 100K points/second 5cm XY accuracy
Outdoor Urban Scanning
Imperfect Scans - Occlusions Point cloud contains holes due to various occlusions (shadows)
Imperfect Scans – Angle & Range Oblique scanning angle Laser energy attenuation on range
Urban Building Characteristics Repetitions, intra symmetry and regularity Axis-aligned basic primitives Dominant planes
SmartBoxes Box-up and Smart!
SmartBoxes Box prior shape fitting Smart context awareness Both Context Data
Live Demo
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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]
Preprocessing Automatic detection of planes and edges assuming dominant orthogonal axes –RANSAC planes –Line sweep edges
Snapping a Box 2D rubber band ROI Collect planes, edges, corners Find the best fitting box using data fitting force D(B,P)
Data fitting D(B,P) snap FacetEdge Data fitting force Data quality ( Confidence + Density ) Distance
Grouping Simple SmartBox Compound SmartBox Align to remove gaps and intersections –cluster and align close to co-linear edges
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
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
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
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
Discrete objective minimization Find linear transformation T(excluding rotation) to minimize: Data fitting forceContextual force
Discrete objective minimization B i-1 B i-2 B i-3 Find linear transformation T(excluding rotation) to minimize: Data fitting forceContextual force
Balance between two forces
Emerging city of Shenzhen, China
Results: textured buildings
Manchester Civil Justice Centre (Manchester, UK) Habitat 67 (Montreal, Canada) The Crooked House (Sopot, Poland)
(Thank You)!