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Digital Elevation Models - WUR - Grontmij
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Digital Elevation Models - WUR - Grontmij

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

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

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Digital Elevation Models - WUR - Grontmij Digital Elevation Models - WUR - Grontmij Presentation Transcript

  • February 25th, 2013 © http://www.viewfinderpanoramas.orgXander Bakker - GIS Team, Grontmij GIS&ICT
  • 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
  • 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 Spot elevation
  • 6 Contour lines
  • 7
  • 8© http://maps.google.com
  • 9
  • 10 No break lines Soft break lines Hard break lines Input dataTriangulation Surface 3D view © http://www.ian-ko.com
  • 11© Ramon Hanssen, TU Delft
  • ght etection nd anging 12
  • ght etection nd anging 13
  • 14
  • 15
  • 16 ‘Raw’ AHN2 points(DSM) Filtered AHN2 points ( DEM)Point cloudTIN
  • 17ditchrivertreeroadhedgefarm
  • 18
  • 19Buildings not in TOP10are detectedBuildings mainlycovered with NoDataare depicted as well
  • 20
  • 21Digital Surface Model Slope GISBuildings footprints AspectCities
  • 22© http://www.iabg.de
  • 23West East Cundinamarca, Colombia
  • 24 3D2D
  • 25 bare earthSoil maps Soil mapsGeoTOP GeoTOP
  • 26
  • 27
  • 28Speed bumps
  • 29 6 7A 2 4 5 8 9B 3 10 11 1 Center of the dike
  • 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!
  • 31height ≥ AB ≤ height < Aheight< BInsufficient dataNo Data
  • 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
  • 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 Sections of 100mDEMDike center line Cross profile H100min Standard profile 3D dike profile
  • 35
  • 36 Standard profiel after iteration H100minStandard profilebefore iteration
  • 37 Z X Y First resultSecond result before correctionafter correctionwith better position
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  • 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
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  • 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