Simulation framework for evaluating lightweight spectral cameras in drone-based aquatic sensing applications.

Optical remote sensing of aquatic environments using aerial drones is becoming more feasible as lightweight, low-power, spectral cameras increase in availability. Use of these cameras in such applications involves complex trade-offs in optical design and in deployment strategies, and simulations provide a means to examine this multidimensional design space to identify specific limitations on performance for a given measurement scenario. In this paper, such a simulation framework is developed, and its use in two realistic aquatic remote sensing scenarios is explored. Such a framework can provide insight into not only uses of existing camera systems, but also aspects of optical design or hardware that would lead to improved accuracy when using such cameras aerially over natural water bodies.

Evaluation of glint correction approaches for fine-scale ocean color measurements by lightweight hyperspectral imaging spectrometers.

Low-power, lightweight, off-the-shelf imaging spectrometers, deployed on above-water fixed platforms or on low-altitude aerial drones, have significant potential for enabling fine-scale assessment of radiometrically derived water quality properties (WQPs) in oceans, lakes, and reservoirs. In such applications, it is essential that the measured water-leaving spectral radiances be corrected for surface-reflected light, i.e., glint. However, noise and spectral characteristics of these imagers, and environmental sources of fine-scale radiometric variability such as capillary waves, complicate the glint correction problem. Despite having a low signal-to-noise ratio, a representative lightweight imaging spectrometer provided accurate radiometric estimates of chlorophyll concentration-an informative WQP-from glint-corrected hyperspectral radiances in a fixed-platform application in a coastal ocean region. Optimal glint correction was provided by a spectral optimization algorithm, which outperformed both a hardware solution utilizing a polarizer and a subtractive algorithm incorporating the reflectance measured in the near infrared. In the same coastal region, this spectral optimization approach also provided the best glint correction for radiometric estimates of backscatter at 650 nm, a WQP indicative of suspended particle load.