1. Bureau of Economic Geology, University of Texas at Austin
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

2. 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

3. 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

4. Variations in Vegetation Removal Parameters

5. Surfer 1meter DEMs

6. Selected LIDAR Points After Vegetation Removal

7. Cross Section Selection

8. Vegetation and Veg-removal Options 1, 2, and 3

9. Vegetation and Veg-removal Options 4 and 5

10. Vegetation Removal Options 1, 2, and 4

11. Problems with Bridges on Waller Creek

12. Bridge Removal in Tegucigalpa, Honduras