1. Digital terrain analyses – DEM principles DEM data structure Lines – contour map Raster – altitude matrix Vector – TIN/Triangular irregular network Vector – TRN/Triangular regular network

2. Digital terrain analyses – DEM principles

6. Digital terrain analyses – DEM principles

7. Continuous fields – TIN (Triangular irregular network)

10. Digital terrain analyses – DEM principles Continuous fields – TIN (Triangular irregular network)

11. Digital terrain analyses – DEM principles TRN – Tringular regular network fast, scale-independent DEM

12. Digital terrain analyses – DEM principles DEM structure advantages/disadvantages LINES ”Hydrologically” correct, best representation, dynamic and flexible Limited analyse possibility Limited visualisation

13. Digital terrain analyses – DEM principles DEM structure advantages/disadvantages Altitude matrix Easy analyses and modelling Redundancy Rigid data structure, resolution Limited adaption to topographic structures

14. Digital terrain analyses – DEM principles DEM structure advantages/disadvantages TIN Complicated data structure Limited analyse possibility Very good terrain representation Good for visualisation, resolution independant

15. Digital terrain analyses – DEM principles

16. Digital terrain analyses – DEM principles DEM generation and assessment Sampling – data source Interpolation Quality assessment Visualisation

17. Digital terrain analyses – DEM principles Sampling - points

18. Digital terrain analyses – DEM principles Sampling

19. Digital terrain analyses – DEM principles Data sources Single points – spread (geodesy, photogrammetry) Single points – regular (direct measurements by plane or satellite (LIDAR), digital photogrammetry) Contours Aim: Interpolate points in a regular grid or corner points of triangles  INTERPOLATION

20. Digital terrain analyses – DEM principles DEM generation and assessment Sampling Interpolation Quality assessment Visualisation

21. Digital terrain analyses – DEM principles TINIDW Thin plate splineTOPOGRID Surf.tps (GRASS) Courtesy Graeme Aggett 2001 Interpolation