Digital Elevation Models - WUR - Grontmij

1,666 views

Published on

This is the presentation given to a delegation of students from Wageningen University (WUR) on Digital Elevation Models

Published in: Technology
1 Comment
15 Likes
Statistics
Notes
No Downloads
Views
Total views
1,666
On SlideShare
0
From Embeds
0
Number of Embeds
6
Actions
Shares
0
Downloads
0
Comments
1
Likes
15
Embeds 0
No embeds

No notes for slide

Digital Elevation Models - WUR - Grontmij

  1. 1. February 25th, 2013 © http://www.viewfinderpanoramas.orgXander Bakker - GIS Team, Grontmij GIS&ICT
  2. 2. 2The digital elevation model represents the bare ground surfacewithout any objects like plants and buildingsA digital elevation model (DEM) is a digital representation ofground surface topography or terrain.A digital elevation model (DEM) is defined as "any digital representationof the continuous variation of relief over space,“ Burrough, 1986Digital Elevation Model (DEM) is a grid where each cell is a valuereferenced to a common datum (sea level), Aronoff 1989
  3. 3. 3
  4. 4. 4In some definitions a DTM is the same as a DEMDTM is defined as spatial distribution of terrain attributes, atopographic map in digital format, that not only consist of theDEM but also slope, aspect and so on… (Meijerink, A. M. J., DeBrouwer, H. A. M., Mannaerts, C. M. & Valenzuela)What’s more important; be aware that there are different definitions!
  5. 5. 5 Spot elevation
  6. 6. 6 Contour lines
  7. 7. 7
  8. 8. 8© http://maps.google.com
  9. 9. 9
  10. 10. 10 No break lines Soft break lines Hard break lines Input dataTriangulation Surface 3D view © http://www.ian-ko.com
  11. 11. 11© Ramon Hanssen, TU Delft
  12. 12. ght etection nd anging 12
  13. 13. ght etection nd anging 13
  14. 14. 14
  15. 15. 15
  16. 16. 16 ‘Raw’ AHN2 points(DSM) Filtered AHN2 points ( DEM)Point cloudTIN
  17. 17. 17ditchrivertreeroadhedgefarm
  18. 18. 18
  19. 19. 19Buildings not in TOP10are detectedBuildings mainlycovered with NoDataare depicted as well
  20. 20. 20
  21. 21. 21Digital Surface Model Slope GISBuildings footprints AspectCities
  22. 22. 22© http://www.iabg.de
  23. 23. 23West East Cundinamarca, Colombia
  24. 24. 24 3D2D
  25. 25. 25 bare earthSoil maps Soil mapsGeoTOP GeoTOP
  26. 26. 26
  27. 27. 27
  28. 28. 28Speed bumps
  29. 29. 29 6 7A 2 4 5 8 9B 3 10 11 1 Center of the dike
  30. 30. 301200 km of dikeEvaluate every 0.5 meterRetrieve 11 heights> 26 million queries… from a dataset with 7 billon pixels (30GB)Read each time only the extent of 1dike into memory. Hours of processingtime reduced to minutes!
  31. 31. 31height ≥ AB ≤ height < Aheight< BInsufficient dataNo Data
  32. 32. 32 More than 1.5m, AHN2 > A More than 70% NoData AHN2 < BInsufficient data, less than 70% NoData, More than 1.5m, B <= AHN2 < Abut no 3 consecutive points with data
  33. 33. 33height ≥ AB ≤ height < AB-10cm ≤ height < BB-20cm ≤ height < B-10cm height ≥ AB-30cm ≤ height < B-20cm B ≤ height < AB-40cm ≤ height < B-30cm height < Bheight < B-40cm Insufficient dataInsufficient data No DataNo Data
  34. 34. 34 Sections of 100mDEMDike center line Cross profile H100min Standard profile 3D dike profile
  35. 35. 35
  36. 36. 36 Standard profiel after iteration H100minStandard profilebefore iteration
  37. 37. 37 Z X Y First resultSecond result before correctionafter correctionwith better position
  38. 38. 38
  39. 39. 39
  40. 40. 40
  41. 41. 41More information about LAStools: https://twitter.com/#!/LAStools http://www.cs.unc.edu/~isenburg/lastools/ http://www.linkedin.com/groups/LAStools-4408378 http://www.facebook.com/LAStools
  42. 42. 42
  43. 43. 43
  44. 44. 44
  45. 45. http://twitter.com/#!/XanderBakker http://nl.linkedin.com/in/xanderbakker Xander Bakker Senior GIS Advisor Xander [DOT] Bakker [AT] Grontmij [DOT] NL http://software.grontmij.nlGrontmij Netherlands BV :: GIS & ICT – GIS Team :: http://www.Grontmij.com :: +31 30 220 79 11

×