Testing a Lower-Cost Mobile Lidar System for Development of a Best Practices Workflow for use in Rapid Coastal Monitoring

This project assesses a lower-cost mobile lidar system, along with a 360-degree spherical camera, to develop a best practices workflow for rapid surveying of sandy beaches. A series of tests were completed to contribute to the workflow, which will include methods for planning, data collection, and post processing. The mobile lidar system, called the HiWay Mapper, is integrated by LidarUSA and consists of a Velodyne HDL-32E, a NovAtel inertial navigation system (INS), and a FLIR Ladybug 360-degree spherical camera. The Velodyne HDL-32E is a lower-cost mobile lidar that contains 32 Class 1, 903 nm laser detector pairs situated in a rotating head, which has a 360° horizontal field of view (FOV) and a 40° vertical FOV. The sensor emits up to ~700,000 pulses per second in single return mode (single, last) and up to ~1,388,928 pulses in dual return mode, with an effective range of 100 m. The INS consists of a 702gg global navigation satellite system (GNSS) and a OEM613 inertial measurement unit (IMU) which has 3 gyroscopes, 3 accelerometers, and collects at 125 Hz. The Ladybug camera contains 5 lenses and records 90% of a full sphere, records up to 30 frames per second, and has an accuracy of 2 mm at 10 m. A series of tests were performed to assess the sensors capabilities and limitations for coastal surveying. These tests consisted of: 1) a calibration test to ensure correct boresight values were used 2) an initialization test for the improvement of INS results, 3) a range test to determine a point cutoff distance, and 4) and ground control point (GCP) test to determine vertical accuracy differences with various target configurations. The results from the calibration test give the correct values to use in ensuing tests and scans. Results from the initialization test show that the INS is aligned faster and has a greater accuracy throughout a scan. The range test determined that a point cutoff distance of no more than 50 meters should be applied to all scans. The GCP test evaluated to determine target spacing and geometry for optimal accuracy. Examples of Ladybug imagery as well as post-processed point cloud data collected using the workflow will be presented via a post-storm scan. Future work will include more thorough ground testing which will include, but not be limited to, unwanted point removal, point cloud colorization, and classification.