Terrestrial laser scans of Nueces River delta By: Matthew Anderson This summer, the CMGL is experimenting with a terrestrial laser scanner, which Dr. Mike Starek borrowed from colleagues at North Carolina State University, in a variety of coastal environments. We are exploring various applications such as erosion and accretion studies and canopy characterization. On June 18, 2013, Alistair Lord, Lihong Su, Michael Starek, Mukesh Subedee, and Matthew Anderson of the Harte’s CMGL lab conducted terrestrial lidar scans in a residential area located in Calallen, Texas, adjacent to the Nueces River delta. Once a location was deemed suitable for scanning, the field crew set up their equipment and began their data collection. Figure 1. The terrestrial lidar scanner is seen in full assembly. Photo credit: Matthew Anderson                For each location, the terrestrial lidar scanner was mounted on a tripod and set level to the ground. Adjacent to the scanner, two sticks of steel rebar were staked into the soil and capped with styrofoam balls. These were used to mark the GPS coordinates for the site as reference. Once the power supply was connected and the software for data collection was ready, terrestrial scans of the location could begin. Figure 2. Michael Starek (bottom right) is seen preparing the necessary software for data collection. Photo credit: Matthew Anderson During the scanning process, the lidar scanner emits a laser reflected vertically by a rotating mirror, while the scanner itself makes a full 360 degree horizontal rotation at its base. This produces a 3D model of the area with a range of 250 meters. Included in the point cloud are models of the surrounding buildings, vegetation, and terrain. Once the scanning process was complete, the field crew disassembled and stored the equipment used for the scan, recorded the GPS coordinates from the rebar markers, and went on to the next location. A total of four terrestrial scans were performed on this day. Figure 3. Mukesh Subedee (center) and Alistair Lord (right) record GPS coordinates using a real time kinematic (RTK) receiver. Photo credit: Matthew Anderson Dr. Lihong Su plans to compare the data from these terrestrial scans with the data collected from aerial scans of the Nueces River delta from 2007. Other future applications from this data include the classification of the surrounding buildings and vegetation, the shape of the canopy for the area, tree metrics, differences in run-off modeling, and how the terrain impacts run-off flow.