Vegetation Removal from LIDAR X, Y, Z Data Sets for Use in Hydrologic Modeling of Waller Creek in Austin, Texas

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Vegetation Removal from LIDAR X, Y, Z Data Sets
for Use in Hydrologic Modeling of Waller Creek in
Austin, Texas

• Rebecca C. Smyth
• Bureau of Economic Geology, University of Texas
  at Austin
• April 24, 2001

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Procedure

• Start with 6.0GB LIDAR file of first and last
  pulse x, y, z points falling within coordinates
  (4 x 9 km area) of Waller Creek watershed
  provided by City of Austin
• Edit out first pulse and intensity data and x, y
  points with long or short ranges (resulting file
  size 1GB). Editing files from 6 to 1 GB must be
  done in UNIX
• Vary veg-removal parameters in 5 different
  scenarios - each scenario takes 7 to 9 hours to
  run on a dual-620MHz processor NT workstation

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Procedure (cont.)

• Extract 150m x 315m sub-areas on UT campus for
  vegetation removal evaluation using awk scripts
  and UWIN program on NT work station
• Generate 1m DEM and point coverage plots for each
  scenario in Surfer
• Digitize cross section in Surfer and extract
  points 5m either side of section using Fortran
  program
• Plot cross sections in Grapher to aid in
  evaluation of parameters

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Variations in Vegetation Removal Parameters
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Surfer 1meter DEMs
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Selected LIDAR Points After Vegetation Removal
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Cross Section Selection
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Vegetation and Veg-removal Options 1, 2, and 3
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Vegetation and Veg-removal Options 4 and 5
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Vegetation Removal Options 1, 2, and 4
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Problems with Bridges on Waller Creek
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Bridge Removal in Tegucigalpa, Honduras