Evaluating the Height of Regional Dikes of HH Rijnland with LiDAR using ArcGIS 10 by Grontmij
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Evaluating the Height of Regional Dikes of HH Rijnland with LiDAR using ArcGIS 10 by Grontmij

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Presentation on how ArcGIS was used to perform an in-depth analysis of the height of regional dikes of HH Rijnland using AHN2 (LiDAR) data.

Presentation on how ArcGIS was used to perform an in-depth analysis of the height of regional dikes of HH Rijnland using AHN2 (LiDAR) data.

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Evaluating the Height of Regional Dikes of HH Rijnland with LiDAR using ArcGIS 10 by Grontmij Evaluating the Height of Regional Dikes of HH Rijnland with LiDAR using ArcGIS 10 by Grontmij Presentation Transcript

  • 2 AHN2 2010 – interpolated AHN2 2008 – interpolated AHN2 2008 – not interpolated Location of dikes
  • 3 AHN2 dataset consists of over 7 billion pixels ( 30GB) Querying the pixels values becomes slower when the size of theraster increments There are 1212 km of dike, every 0.5m 11 pixels are queried ( 27million points) and evaluated against 2 reference heights For each point on a dike there should be al least a length of 1.5mconnected within a class No standard tools available for this specific task
  • 4 Merge AHN2 tiles to 1 raster dataset loop through dikes  fetch height every 0.5m  evaluate against two reference heights (A and B)  AHN2<B or B<=AHN2<A or AHN2>=A or NoData  Combine points with same class together to form a line  next point on dike next dike(repeat validationfor reference heights C and D) > 1.5m, it does meet the criteria
  • 5 For each class (AHN2<B, B<=AHN2<A, AHN2>=A) register thenumber of consecutive points that fall inside that class The highest class with at least 3 consecutive points is assigned In the example below the resulting class is B<=AHN2<A, basedon points 4 to 9 which are higher that B, but not all above A (thelower limit of a class is used for validation) 6 7 A 2 4 5 8 9 B 3 10 11 1 Dike center
  • 6
  • 7ClassPoint >= AB <= Point < APoint < BNoData
  • 8ClassAHN2 >= AB <= AHN2 < AAHN2 < BInsufficient dataNoData
  • 9ClassAHN2 >= AB <= AHN2 < AAHN2 < BInsufficient dataNoData
  • 10ClassAHN2 >= AB <= AHN2 < AAHN2 < BInsufficient dataNoData
  • 11More 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
  • 12Correct method of processing solitary points
  • 13AHN2 >= A AHN2 >= AB <= AHN2 < A B <= AHN2 < AAHN2 < B AHN2 < BInsufficient data Insufficient dataNoData NoData
  • 14AHN2 >= A AHN2 >= AB <= AHN2 < A B <= AHN2 < AAHN2 < B Bmin10 <= AHN2 < BInsufficient data Bmin20 <= AHN2 < Bmin10NoData Bmin30 <= AHN2 < Bmin20 Bmin40 <= AHN2 < Bmin30 AHN2 < Bmin40 Insufficient data NoData
  • 15
  • 16 Calculate percentage of total length per class per dike Sums 100% Explanation of the column names:  “KL” stands for class  “X” represents AHN2 value  “lt” is less than “<“  “le” is less equal “<=“  “ge” is greater equal “>=“ So “KL_BleXltA” means: Class where B <= AHN2 < A
  • 17Percentage per class (based on A and B) Percentage per class (based on C and D)
  • 18 The 1212 km of dike has been processed into classified pointsand lines and additionally aggregated per dike Processing time has been reduced to 12 minutes for the entirearea based on the 30 GB raster. For each point information about:  %NoData (indicates reliability)  elevation (min, max, mean)  classification For each polyline information about:  elevation (min, max, mean)  classification
  • 19 After the height test, the results were combined with knowninstabilities and observations from previous research andfieldwork, in order to derive those locations with the highestpriority.
  • 20 indicating the percentage of adike with sufficient stability tosafeguard the surrounding area
  • 21 Sufficient height Height shortage between 0 and 10 cm Height shortage between 10 and 20 cm Height shortage between 20 and 30 cm indicating the amount of lacking Height shortage more than 30 cm NoDataheight to safeguard the Insufficient data to quantifysurrounding area
  • 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