Inside Unmanned Systems

APR-MAY 2018

Inside Unmanned Systems provides actionable business intelligence to decision-makers and influencers operating within the global UAS community. Features include analysis of key technologies, policy/regulatory developments and new product design.

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56   April/May 2018 unmanned systems inside AIR TRAINING asprs review for direct map production. It needs no ground con- trol points except for quality control. DG is a cost-effective enabling technology for LiDAR, search and rescue and Multibeam Sonar, making it ideal for emergency situations such as oil spills, disaster relief/response and similar applica- tions that require comprehensive map data very quickly and accurately. "With DG, survey and mapping teams can collect images and post-process in a fraction of the time compared to AT and the data gathering effort will require fewer people and less equipment. Most im- portant, you'll deliver the best possible accuracy on projects where human safety and your reputation is on the line," Mostafa said. The most common applications of LiDAR in to- day' market are corridor mapping such as roads, railways, pipelines, waterway landscapes and elec- trical transmission lines (about 65 percent). Other applications include mining, coastal mapping and avalanche prediction, as well as rapid response such as natural disasters, oil spills or well leaks. Less common applications include forestry, hydrology and geology. RE-ALIGNED FOR ACCURACY Mostafa closed out the discussion with a compari- son of photogrammetry and LiDAR, as well as his recommended best practices for planning, execu- tion and post-processing missions. Enabling Technology for: • LiDAR •  SAR • No GCP (Q/C) •  Multibeam Sonar Optional but Excellent for: • Cameras (Corridor Mapping and Corner Cases) Cost Effective: • Minimize the Use of GCPs (QA/QC only) • Easier AT Fast (Emergency Situations): • Oil Spills, Leaks of Wells, Forest Fires, Earthquakes Here are a few points to keep in mind: Mission Prep/Base Stations: • No less than 4 hours of observation if goal is centimeter accuracy • Minimize baseline separation to <20 km • Keep away from trees and buildings to mini- mize ref lections causing multipth problems Mission Execution • Continuously monitor the inertial sensor for navigation changes • Regularly check data recording device to make sure data is logged as expected RTK or PPK Advantages Limitations • 1/2 Exterior Orientation •  Homogeneous Block Adjustment • No GCP (Q/C) •  Approximate Camera Model Only • Full Block Only •  High Sidelap (80%) = more flying •  High Density Point Matching = Slow Processing DG Advantages Limitations •  Full Exterior Orientation •  Homogeneous Block Adjustment • No GCP (Q/C) •  Low Sidelap (40%) = Less Flying, Fewer Photos •  Single-Strip •  Single-Model •  Low Density Point Matching = Fast • None efficiency Why use direct Georeferencing? Type/Size of Project Ortho Maps Corridor Mapping Planimetric Mining Agriculture Construction AT PPK DG Source: Dr. Mohamed Mostafa, Chair of the ASPRS Precision Mapping by UAS Committee and Director of Microdrones mdSolutions Team

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