Direct Georeferencing of a Pushbroom, Lightweight Hyperspectral System for Mini-UAV Applications

• Published in: Remote sensing (Basel, Switzerland) Vol. 10; no. 2; p. 204
• Main Authors: Jaud, Marion, Le Dantec, Nicolas, Ammann, Jérôme, Grandjean, Philippe, Constantin, Dragos, Akhtman, Yosef, Barbieux, Kevin, Allemand, Pascal, Delacourt, Christophe, Merminod, Bertrand
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-01-2018; MDPI
• Subjects: Accuracy; Cameras; Coastal waters; Data processing; Earth Sciences; Environmental science; Geophysics; georectification; hyperspectral cube reconstruction; Hyperspectral imaging; hyperspectral mapping; Inland waters; Platforms; Polls & surveys; Proprioception; Pushbroom sensor modes; Remote sensing; Satellites; Sciences of the Universe; Sensors; Spatial discrimination; Spatial resolution; Specifications; Spectral resolution; Systems design; Unmanned Aerial Vehicle (UAV); Unmanned aerial vehicles; Unmanned aircraft; hyperspectral cube reconstruction; Unmanned Aerial Vehicle (UAV); hyperspectral mapping; georectification
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs10020204

Hyperspectral imagery has proven its potential in many research applications, especially in the field of environmental sciences. Currently, hyperspectral imaging is generally performed by satellite or aircraft platforms, but mini-UAV (Unmanned Aerial Vehicle) platforms (<20 kg) are now emerging. On such platforms, payload restrictions are critical, so sensors must be selected according to stringent specifications. This article presents the integration of a light pushbroom hyperspectral sensor onboard a multirotor UAV, which we have called Hyper-DRELIO (Hyperspectral DRone for Environmental and LIttoral Observations). This article depicts the system design: the UAV platform, the imaging module, the navigation module, and the interfacing between the different elements. Pushbroom sensors offer a better combination of spatial and spectral resolution than full-frame cameras. Nevertheless, data georectification has to be performed line by line, the quality of direct georeferencing being limited by mechanical stability, good timing accuracy, and the resolution and accuracy of the proprioceptive sensors. A georegistration procedure is proposed for geometrical pre-processing of hyperspectral data. The specifications of Hyper-DRELIO surveys are described through two examples of surveys above coastal or inland waters, with different flight altitudes. This system can collect hyperspectral data in VNIR (Visible and Near InfraRed) domain above small study sites (up to about 4 ha) with both high spatial resolution (<10 cm) and high spectral resolution (1.85 nm) and with georectification accuracy on the order of 1 to 2 m.