By Paolo Franchi
Study on using laser imaging and LIDAR on-board an autonomous platform as a multi-modality sensor system for water column and seabed surveying. Trees, Charles; Fournier, Georges. CMRE-FR-2015-005. April 2015.
The GCLAS (Gated Imaging Camera, LIDAR and ADCP/Sonar on a Coastal Glider) feasibility study, combines both acoustic and imaging technologies with autonomous on-board data processing. The approach uses multiple acoustical and optical sensors installed and integrated on a mobile observational platform (Coastal Glider Extended, CGX), that would provide unattended surveying of the water column and seabed, utilizing "reactive behaviour-based" control for both the platform missions and sensor acquisitions and storage. The range-gated imaging and LIDAR sensor SLICaL (Stereoscopic Laser Imaging Camera and LIDAR) would be Radiometrically Characterized and Calibrated (RC2), which has not been done previously to our knowledge, following measurement protocols developed by National Metrology Institutes. With this calibrated imagery and LIDAR data, robust algorithms can be developed to interpret and convert the raw data into derived products at known uncertainties. The optical properties derived from the LIDAR and the other optical sensors would be used to optimize the collection of the laser-gated camera imagery so that only high quality images would be collected for target classification and identification. The sonar would search for targets, whereas the optical camera system would provide the identification and classification. Although the AUV-glider platform is mobile, it does have a mode that can be used to repeatedly sample an area, using a ?virtual station keeping? mission. It can also sit at the surface and with the LIDAR capabilities vertically sample the water column down to 50m or more at 1m intervals. Given the autonomy and endurance of the GCLAS system, it would have the capability to completely characterize the sea column and image the seabed over a path of more than 800km in a two-week period (depending upon improved battery utilization, it's mission may last up to three weeks). This glider data can also be used to better understand and characterize oceanic and coastal physical and bio-optical variability at basin scale, mesoscale, and even sub-mesoscale (ranging from 100 km horizontally in a month to 1 km in an hour).