Session 8A, Paper 2

5. Preparation of the polygon data base • Identifying meaningful structures • Understanding the spatial arrangement between them Unstructured data set Retrieving information More meaningful homogeneous regions ( e.g. land-use parcels)

6. Test environment: LiDAR data

7. First order information TIN based on the Delaunay triangulation, the maximal planar description of the given point set (Kirkpatrick and Radke, 1985)

8. TIN facets binary classification ( using 45 ° slope threshold )

9. Graph of adjacencies construction

10. Depth-first search vs. Breadth-first search 15 graph vertices 6 2 3 12 11 9 7 4 5 8 10 13 15 14 1 6 2 3 12 11 9 7 4 10 15 14 1 8 13 5 Depth - first search Breadth - first search 1 6 2 3 12 11 9 7 4 5 8 10 13 15 14 traversed edges LEGEND 1, 1,…, 6 2 3 12 11 9 7 4 5 10 13 15 14 1 8

11. 3

13. Problem: containment relationship between rings of “steep” polygons and “flat” polygons 200 Graph vertices Graph edges Polygon arcs Polygon nodes “ Flat” polygons “ Steep” polygons LEGEND 250 256 257 260 200

14. Graph of “touchings” between “steep” polygons

16. Summary and further work Unstructured data (LiDAR points) TIN Features Understanding process Polygonal regions (x,y,z) coordinates Structures clustering into homogeneous regions Binary classification based on Δ slopes Identification of meaningful structures Cluster shapes delineation, derivation of its characteristics for the identification of higher order structures