The National Science Foundation created a research center to support the use of airborne laser mapping technology for the scientific community. The NSF supported National Center for Airborne Laser Mapping (NCALM) is operated jointly by the Department of Civil & Environmental Engineering, Cullen College of Engineering, University of Houston, and the Department of Earth & Planetary Science, University of California, Berkeley. NCALM uses an Airborne Laser Swath Mapping (ALSM) system based at the UH Geosensing Imaging & Mapping Laboratory. The state-of-the-art laser surveying instrumentation and GPS systems collect data in areas selected through the competitive NSF grant review process.
The ALSM observations are analyzed at both Houston and UC Berkeley and then made available to the Principal Investigator through an archiving and distribution center at UCB – building upon the Berkeley Seismological Laboratory's Northern California Earthquake Data Center system. Both the UH and UC Berkeley groups contribute to software development that increase the processing speed and data accuracy. NSF supported researchers must contact NCALM during proposal preparation to obtain guidance on cost estimates, scheduling, and related issues. Once funded, PIs and their students will be able to participate in all phases of the work.
Research-grade ALSM data can be used to produce highly accurate, three-dimensional, digital topographic maps of large areas of land surface. The major component of a mapping system is a laser that emits tens of thousands of short pulses of light per second. The laser is mounted in a twin-engine aircraft, and the laser pulses are directed toward the ground by a scanning mirror. Each pulse illuminates an area, or footprint, of about one foot in diameter, and the light is scattered back to a sensor in the aircraft. The round-trip travel time of the laser light allows researchers to compute the precise three-dimensional locations of points on the ground. The resulting set of latitudes, longitudes, and heights of many millions of points is then transformed into a highly accurate map.
Airborne Laser Swath Mapping has proven to be a powerful tool for accurately and densely mapping large areas of land. Researchers have used ALSM data to explore geological and geomorphological processes such as faulting and channelization. The power of laser mapping lies not only in quantifying what is immediately visible, but in revealing the landforms that lie below natural and man-made obstructions. Researchers can now gain a clear glimpse of terrain features more rapidly than before.
Continuous advances are being made in improving the quality of the data to meet the needs of scientific research. Researchers are exploiting the use of high-resolution and accurate ALSM data not available before. Height accuracy of less than 10 cm is providing researchers new opportunities and means to make scientific discoveries never realized in the past.