Microbolometer thermal cameras in UAVs and manned aircraft allow for the acquisition of highresolution temperature data, which, along with optical reflectance, contributes to monitoring and modeling of agricultural and natural environments. Furthermore, these temperature measurements have facilitated the development of advanced models of crop water stress and evapotranspiration in precision agriculture and heat fluxes exchanges in small river streams and corridors. Microbolometer cameras capture thermal information at blackbody or radiometric settings (narrowband emissivity equates to unity). While it is customary that the modeler uses assumed emissivity values (e.g. 0.99– 0.96 for agricultural and environmental settings); some applications (e.g. Vegetation Health Index), and complex models such as energy balance-based models (e.g. evapotranspiration) could benefit from spatial estimates of surface emissivity for true or kinetic temperature mapping. In that regard, this work presents an analysis of the spectral characteristics of a microbolometer camera with regard to emissivity, along with a methodology to infer thermal emissivity spatially based on the spectral characteristics of the microbolometer camera. For this work, the MODIS UCBS Emissivity Library, NASA HyTES hyperspectral emissivity, Landsat, and Utah State University AggieAir UAV surface reflectance products are employed. The methodology is applied to a commercial vineyard agricultural setting located in Lodi, California, where HyTES, Landsat, and AggieAir UAV spatial data were collected in the 2014 growing season. Assessment of the microbolometer spectral response with regards to emissivity and emissivity modeling performance for the area of study are presented and discussed.
The demands of the unmanned airborne multispectral surf-zone mine counter-measures (MCM) mission require high spatial resolution. Weight, volume and power constraints preclude stabilized operation of the cameras for this application. Further, the system is to be flown on a rotary-winged platform, with its attendant vibration characteristics. Thus, the MTF needs to be measured in flight to insure it meets the resolution requirements. We apply the slanted-edge MTF method to the in-flight characterization of airborne high-resolution cameras, analyzing images of orthogonal slanted edges to estimate the motion and vibration contributions to the MTF, and show that the system meets its requirements. We also apply a methodology for scaling to other altitudes and speeds to show that the system will have excellent imaging performance throughout its operational envelope. For our application, the slanted-edge method is more accurate and reproducible than the alternative of placing MTF bar targets under the aircraft flight path. Further, the slanted-edge targets are much easier to deploy and recover, and ease the navigation tolerances.
The design, operation, and performance of the fourth generation of Science and Technology International's Advanced Airborne Hyperspectral Imaging Sensors (AAHIS) are described. These imaging spectrometers have a variable bandwidth ranging from 390-840 nm. A three-axis image stabilization provides spatially and spectrally coherent imagery by damping most of the airborne platform's random motion. A wide 40-degree field of view coupled with sub-pixel detection allows for a large area coverage rate. A software controlled variable aperture, spectral shaping filters, and high quantum efficiency, back-illuminated CCD's contribute to the excellent sensitivity of the sensors. AAHIS sensors have been operated on a variety of fixed and rotary wing platforms, achieving ground-sampling distances ranging from 6.5 cm to 2 m. While these sensors have been primarily designed for use over littoral zones, they are able to operate over both land and water. AAHIS has been used for detecting and locating submarines, mines, tanks, divers, camouflage and disturbed earth. Civilian applications include search and rescue on land and at sea, agricultural analysis, environmental time-series, coral reef assessment, effluent plume detection, coastal mapping, damage assessment, and seasonal whale population monitoring
A fast tip-tilt secondary is being implemented on the University of Hawaii 2.2-m telescope, to provide image quality to match the site characteristics of Mauna Kea, and complement the existing wide-field RC secondary.
This paper describes a low cost adaptive optics (AO) instrument that is being built for the f/31 focus of the UH 2.2m telescope. While operating within the low cost constraint, we have tried to maximize the flexibility and usefulness of the instrument, and minimize the impact of the necessary performance compromises. We have used off-the-shelf optical and electronic components wherever possible, and have emphasized simplicity of design throughout the instrument. The UH prototype AO system, on which the 2.2m AO system is based, is described elsewhere, thus the principles of operation of the UH 2.2m instrument will not be described in detail here.
We present the first results from the University of Hawaii Institute for Astronomy project to develop largeformat optical CCD mosaics for the telescopes on Manna Kea. We have constructed two 4096 x 4096 mosaics: both are 2 x 2 arrays of 2-edge abuttable 2048 x 2048 15tm pixel imagers built by Loral Aeronutronics. The first mosaic is constructed using an abuttable package design yielding an array that can be assembled and disassembled using the bestavailable separatelytested quadrants. The second mosaic is formed by packaging a monolithic quad die consisting of four functioning 2048 x 2048 devices from a single wafer. In addition to the mechanical design of the focal plane and dewar we describe the system used to operate the CCDs including the programmable DSP-based CCD controller and our high-speed serial interface into the DSP port of a NeXT computer workstation. We present our initial x-ray and optical test results from the " monolithic mosaic" and our first data from the telescope. 1
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