1. Airborne LIDAR (Light Detection And Ranging) at the University of Texas
R. Gutierrez, J. Gibeaut, R. Smyth, T. Hepner,
J. Andrews, J. Bellian
Bureau of Economic Geology, University of Texas at Austin
M. Crawford, B. Schutz, A. Neuenschwander,
J. Trelogan, C. Weed
Center for Space Research , University of Texas at Austin
W. Gutelius and Others
Optech, Inc., Toronto

2. LIDAR facts Pioneered by NASA Airborne Terrain Mapper Group
Commercial surveys started in mid 1990’s
About 45 LIDAR groups in the world today
Provides topographic data with 10 to 50 cm
vertical accuracy and 1 m data point
spacing

3. Status of LIDAR in Texas, 2010
With that quick review you may ask where are we in Liar acquisition for the state. The red But this is a basin wide approach areas are LIDAR that has been acquired and the blue the LIDAR to be acquired. This may seem small but it is a large area.

4. OBJECTIVES of UT GROUP
Apply detailed LIDAR surveys to a variety of research problems including:
Coastal erosion.
Land cover classification.
Water resource issues.
Flood hazard prediction.
Archaeological investigation.
Improve analysis techniques:
Removal of vegetation and man-made structures.
Incorporation of intensity data.
Improve accuracy and data quality:
Develop site-specific survey procedures.
Improve GPS accuracy.

5. HOW IT WORKS Mirror sweeps laser beam across the ground.
Range to target is determined by measuring time interval between transmission and return of reflected laser pulse.
Aircraft position is determined using GPS phase differencing techniques.
Pointing direction of laser determined with Inertial Measuring Unit (IMU) and recording of mirror position.
Data streams recorded and synchronized for post processing.

6. Elevation accuracy 10 to 25 cm depending on survey height of aircraft.
Laser pulse rate: up to 25,000 per sec.
Operating altitude: ,000 meters.
Swath width: up to 1,500 meters at 2,000 meter altitude.
Records first and last returns of individual pulses.
Records intensity.
Installable in a variety of aircraft including a single engine Cessna 206.

7. DETAILS/PROBLEMS Calibration Shadowing Vegetation penetration
Long and short ranges
Multipathing
Ground control
Datums

8. ACCURACY Laser ranging: 1 or 2 cm
GPS positioning standard deviation: 5 to 7 cm
GPS positioning/system bias: 0 to 40 cm
IMU/scanner mirror accuracy: degrees
which means at 1,000 m AGL
and at edge of 20 degree scan, error in z = 14 cm
error in x,y = 40 cm
Laser spot size averaging: depends on terrain

16. Matagorda Peninsula