Houston, US: Increasing its cadre of laser mapping researchers, the University of Houston will expand its work in homeland security, disaster recovery, oil and gas exploration, wind farm site planning and environmental studies. The NSF National Center for Airborne Laser Mapping (NCALM) and the researcher leading it recently moved operations to the University of Houston (UH). Based upon historical information, revenues generated by the centre’s operation are anticipated to be USD one million per year and will be reinvested in the programme.
Ramesh Shrestha, Hugh Roy and Lillie Cranz Cullen, Civil and Environmental Engineering Professor, brought NCALM to UH from the University of Florida. He has been director of the centre, focused on ground-based scanning laser technology and airborne laser swath mapping research, since it was established in 2003. Shrestha brought much of his Florida team with him to Houston, where they now operate NCALM jointly with the University of California-Berkley.
Shrestha said, “With the centre, we have brought laser mapping’s uses to the forefront and expect to continue to have this impact in our new Houston home. We plan to establish curriculum catered to this specialty and eventually add a graduate degree in geosensing systems engineering. This is in addition to carrying out research far surpassing what is capable in laser mapping to date.”
Bill Carter, a research professor at UH, said, “Together (with Shrestha), we saw its potential to exceed what was possible with many traditional methods, such as airborne photogrammetric mapping that uses cameras to detail terrain. Laser mapping has the ability to work day or night, as well as generally map areas even though they were covered by forests and other vegetation where photogrammetric methods could not.”
It was not long before other scientists would see its same benefits, especially as the two developed techniques to remove and minimize some of the errors seen in the early years. Their equipment became fine-tuned to collect even more data, now mapping as many as 167,000 points per second compared to the 3,000 they were able to achieve when they first started.
Aided by NSF, future NCALM efforts explore the possibility of using Light Detection and Ranging (LiDAR) to map everything from glacial movements to the migration of penguin colonies in Antarctica. Using LiDAR, researchers take measurements of the ground’s surface from their Cessna 337 Skymaster airplane.
From roughly 2,000 feet, this remote technology measures properties of scattered light through the use of laser pulses. Thousands of small cone-shaped pulses travel through a hole in the bottom of the plane to the ground below, and a unique detector picks up rays reflected from the ground. Then, each point’s distance is determined by measuring the time delay between the transmission of a pulse and the detection of reflected signals. The plane’s location and movement in the air are tracked by an inertial measurement unit fixed inside the laser system with a GPS receiver mounted to the plane and others on the ground. Both are used, along with the laser data, to produce detailed 3-D topographical images of the terrain.
“In coming years, our group plans to develop a next-generation LiDAR system. The unit would be less expensive than commercially available systems and allow for some of the most accurate, highest-resolution observations possible in laser mapping. We want to develop a system like no one else has developed. It would really change what could be done with this technology. It would have new features, be faster, smaller and capture more during each flight than we can today,” continued Shretha.
According to Shrestha, this system would use a much shorter pulse-length laser, increasing the number of points that could be mapped per second to 800,000. This would add to data accuracy and reduce the amount of time needed in the air to collect the information. Additionally, it would be able, for the first time, to penetrate shallow water depths.
Source: University of Houston