Small Unmanned Aircraft Systems for High-Resolution Thermal Mapping: An Application for Freeze–Thaw Remote Sensing

The use of small Unmanned Aircraft Systems (sUAS) for scientific research and industry applications has grown rapidly in recent years. As these technologies have developed and become increasingly affordable, their use for thermal inspections and imaging has risen steeply. In an effort to map parts of the Earth’s surface at increasingly high resolutions, we have implemented a relatively simple and affordable sUAS based thermal imaging system. Utilizing a DJI Inspire 2 drone with dual-gimbal mounted FLIR Vue Pro R (45°FOV, 640x512 pixels) and Zenmuse X4S (20 megapixels) cameras, we have captured radiometric thermal images coincident with visible light images in multiple test study locations. The primary goal through the development of this system is to measure surface temperature at high resolutions (~1-3 cm, with 20-30m acquisition altitude). This is done in order to help characterize surface freezing and thawing (FT) processes at small scales with potential for improving global satellite temperature and FT products. Imaged areas include parts of Grand Mesa, CO at >3,000 m during the snow melt period. As part of our system, ground control points are used to help calibrate and geolocate the acquired thermal images. We will present some of the challenges, early imaging results, and future directions planned for the use of this sUAS-based thermal imaging system. Improving image calibration and processing techniques will enable the mapping of larger regions at high resolutions, a primary objective of this observation system. This capability will help in determining the small-scale heterogeneity of surface thaw and snowmelt, thus improving our understanding of FT processes and contributing to the enhancement of FT remote sensing products.