HR: 0830h
AN: G11A-0240    [PDF]
TI: Using Artifacts to Detect Systematic Errors in ALSM Observations
AU: * Luzum, B J
EM: luzum@ufl.edu
AF: University of Florida, 365 Weil Hall Department of Civil and Coastal Engineering, Gainesville, FL 32611 United States
AU: Carter, W E
EM: bcarter@ce.ufl.edu
AF: University of Florida, 365 Weil Hall Department of Civil and Coastal Engineering, Gainesville, FL 32611 United States
AU: Sartori, M
EM: michaels@ufl.edu
AF: University of Florida, 365 Weil Hall Department of Civil and Coastal Engineering, Gainesville, FL 32611 United States
AU: Shrestha, R L
EM: rshre@ce.ufl.edu
AF: University of Florida, 365 Weil Hall Department of Civil and Coastal Engineering, Gainesville, FL 32611 United States
AB: Even well calibrated Airborne Laser Swath Mapping (ALSM) data contains systematic errors. Evidence of these errors can be seen in distinctive artifacts found in the digital models created from the ALSM data. For instance, errors in the automatic gain control or the range walk lookup table could cause intensity-related artifacts that become especially obvious on smooth surfaces as spurious elevations. Also, errors in the trajectory of the sensor, reading the scanner mirror angle, the scale, and the range walk lookup table can cause the elevations in adjacent ALSM strips to not match in the overlap areas. Careful calibration and reduction needs to be performed to reduce these effects to an acceptable level. The remaining errors can be further reduced by new post-processing algorithms. As an example, since some errors increase as the scan angle increases, the inter-strip inconsistencies (sometimes called seams) can be decreased by using schemes which decrease the weight of data as it gets further from nadir. With the effects of the errors minimized, the resulting ALSM elevation and intensity data show a wealth of features. ALSM data users need to be aware of the possible sources of contamination and need to ensure that their data will suit their needs. The flight specifications need to be made not just considering the obvious data spacing and accuracy, but also accounting for secondary concerns such as the desire to have the laser shots penetrate the vegetation canopy and to get returns from dark surfaces. Although increasing the overlap and low flying heights can be seen by some as counterproductive to the efficiency of data collection, the resulting quality of the product often outweighs the `cost' of additional data collection and processing time.
DE: 1294 Instruments and techniques
DE: 1625 Geomorphology and weathering (1824, 1886)
DE: 1800 HYDROLOGY
SC: Geodesy [G]
MN: 2003 Fall Meeting