A Methodology for Consistent Georegistration in Underwater Hyperspectral Imaging

• Published in: IEEE journal of oceanic engineering Vol. 47; no. 2; pp. 331 - 349
• Main Authors: Lovas, Havard Snefjella, Mogstad, Aksel Alstad, Sorensen, Asgeir J., Johnsen, Geir
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Calibration; Cameras; Color imagery; Coral reefs; Distortion; Field of view; Fjords; Hyperspectral imaging; Imagery; Imaging techniques; Laboratories; Mapping and monitoring; Mathematical models; Methodology; Ocean floor; Photogrammetry; Position measurement; Remotely operated vehicles; Solid modeling; Three dimensional models; Underwater; underwater hyperspectral imaging (UHI); Water temperature
• ISSN: 0364-9059; 1558-1691
• DOI: 10.1109/JOE.2021.3108229

This article proposes a novel methodology for precise georegistration in underwater hyperspectral imaging (UHI) using a red-green-blue (RGB) camera to build a photogrammetry model that estimates the pose and a 3-D seabed model. The two main scientific contributions are: 1) the development of two methods for geometric calibration of the hyperspectral imager (HSI) with the RGB camera and 2) the development of a methodology for consistent georegistration of the pushbroom hyperspectral imagery on the seabed using the photogrammetry model and the geometrically calibrated HSI. The georegistration uses a calibrated RGB camera, fixed to the HSI, with an overlapping field of view. The RGB images are used to build a photogrammetry model. Through utilizing the geometric HSI parameters from the calibration, the hyperspectral imagery is ray cast onto the 3-D model. This methodology is exemplified for UHI from a remotely operated vehicle on a cold-water coral reef in the Trondheim Fjord, Norway. The precision is unprecedented for georegistration in UHI, demonstrated by the first-ever spatially consistent UHI mosaic to contain multiple transects.