NASA Ames developed a novel remote sensing instrument with advanced scientific capabilities for Multispectral Imaging, Detection and Active Reflectance (MiDAR). The MiDAR transmitter and receiver demonstrate a cost-effective solution for simultaneous high-frame-rate, high signal-to-noise ratio (SNR) multispectral imaging, with hyperspectral potential, high-bandwidth simplex communication, and in-phase radiometric calibration. The use of computational imaging further allows for multispectral data to be fused using Structure from Motion (SfM) and fluid lensing algorithms to produce 3D multi-spectral scenes and high-resolution underwater imagery of benthic systems as part of future scientific airborne field campaigns.
The MiDAR transmitter emits coded narrowband structured illumination to generate high-frame-rate multispectral video, perform real-time radiometric calibration, and provide a high-bandwidth simplex optical data link under a range of ambient irradiance conditions including darkness. A theoretical framework, based on unique color band signatures, is developed for multispectral video reconstruction and optical communications algorithms used on MiDAR transmitters and receivers.
Experimental tests demonstrate efficient, radiometrically calibrated, high SNR active multispectral imaging in seven channels from 405-940 nm at 2048 × 2048 pixels and 30 Hz. The MiDAR prototype consists of an active array of multispectral, high-intensity, light-emitting diodes (MiDAR transmitter) coupled with a state-of-the-art, high-frame-rate NIR computational imager (the NASA FluidCam NIR) that functions as a MiDAR receiver. The tests demonstrate a cost-effective and adaptive sensing modality with the ability to change color bands and relative intensities in real time in response to changing science requirements or dynamic scenes.
Potential applications of MiDAR include high-resolution nocturnal and diurnal multispectral imaging from air, space, and underwater environments as well as long-distance optical communication, bidirectional reflectance distribution function characterization, mineral identification, atmospheric correction, UV/fluorescent imaging, 3D reconstruction using SfM, and underwater imaging using fluid lensing. Multipurpose sensors, such as MiDAR, that fuse active sensing and communications capabilities may be particularly well-suited for mass-limited robotic exploration of Earth and the solar system and represent a possible new generation of instruments for active optical remote sensing.