Drone Polariscopy—Towards Remote Sensing Applications

Remote sensing is critical for a wide range of applications, including ocean and wave monitoring, planetary exploration, agriculture, and astronomy. We demonstrate a polariscopy concept that is able to determine orientation of patterns below the optical resolution limit of a system. This technique relies on measuring at least four different polarisation angles and calculating the orientation from this set of intensity information. It was initially demonstrated on the Infrared Microspectroscopy Beamline at the Australian Synchrotron using IR light in transmission. Using a monochrome polarising camera mounted onto a drone as a remote sensing platform analogue, orientation information was extracted from 3D-printed targets in reflection. The images were taken at an altitude where conventional imaging could not resolve the test patterns. The system had a 3.33 mm ground resolution. Patterns consisting of 0.5 mm lines spaced 0.5 mm apart were detected using the method, demonstrating the capability of detecting features over six times smaller than the resolution limit. In the interest of moving towards high-speed data acquisition and processing, two methods for processing the image are compared—an analytical and a curve fitting method.