1. Work Progress Ameni SASSI Serge MIGUET 1 The Influence of Topography and Vegetation Context on Representations of Large Urban Landscape Meeting-Workshop SKYLINE June 24th 2015

2. Skyline’s Geometric Description Proposed Method Natural Part ≠ Buildings Part Irregular Forms ≠ Regular Forms Short Segments ≠ Long Segments High Curvature ≠ Flat Curvature 2 Natural Part Buildings Part

3. Skyline’s Geometric Description Straight Lines Classification Long straight segments Segments Length Segments Numbers 3 Many very short segments Natural Landscape_2New York

4. Skyline’s Geometric Description Straight Lines Classification ? ? 4 Istanbul Vancouver

5. Segment’s size Segments Number * Size Segments Number Cumulated Histogram 100% 50% Mean Segments size The mean segments size could be an index to describe the skyline segments in a general way: the skyline is almost natural or artificial? Skyline’s Geometric Description Straight Lines Classification

6. LandscapeMean Segments size Index New York16 Chicago13 Dubai7 Shanghai7 Madrid10 Londres9 Istanbul5 Vancouver12 Natural Landscape_27 Natural Landscape_39 Natural Landscape_49 Skyline’s Geometric Description Straight Lines Classification ? Proceed with another descriptor of the skyline, more accurate => the Curvature Scale Space descriptor

7. Curvature Scale Space Descriptor « a local measure on how fast a planar curve is turning » The extracted skyline  Curve Γ(u)=(x(u),y(u)) The curvature function: Skyline’s Geometric Description Curvature Analysis Curvature Skyline Points

8. Skyline’s Geometric Description Curvature Analysis 8 Dubai Straight Lines of Buildings are noticeable with Yellow color Natural Landscape_3 High values of negative/positive curvature Curvature k(u)< 00> 0 SkylineConcavity Point FlatConvexity Point

9. Compute the CSS Image  the scale of persistence of each point in the skyline during the smoothing process Buildings’ corners still appear in high scales? Small details: Trees, vegetation disappear from very low scale levels? Skyline’s Geometric Description Future Work Scale Curve Points