Multiangle technique for measurement of ground-source emission
01 Apr 1995-Vol. 2471, pp 411-421
TL;DR: In this paper, the authors demonstrate the advantage of using a large number of viewing angles to overconstrain the inversion problem for critical atmospheric and source parameters, and show that source temperature errors of less than 1K should be possible.
Abstract: TAISIR, the Temperature and Imaging System Infrared, is a nominally satellite based platform for remote sensing of the earth. One of its design features is to acquire atmospheric data simultaneous with ground data, resulting in minimal dependence on external atmospheric models for data correction. One technique we employ to acquire atmospheric data is a true multi-angle data acquisition technique. Previous techniques have used only two angles. Here we demonstrate the advantage of using a large number of viewing angles to overconstrain the inversion problem for critical atmospheric and source parameters. For reasonable data acquisition scenarios, simulations show source temperature errors of less than 1K should be possible. Tradeoffs between flight geometry, number of look angles,, and system signal-to-noise are given for typical parameter ranges.
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29 Sep 1995
TL;DR: In this paper, the authors used the multi-angle data acquisition technique to determine the source specular reflectivity to approximately 0.05 if there is very good system performance (NETD {approx} 0.01 K).
Abstract: The remote measurement of the emissivity of ground materials is of tremendous value in their identification and mapping. Traditional techniques use reflected solar radiation for this measurement for wavelengths shorter than 5 {mu}m. With the development of new techniques, the 10 Jim atmospheric transmission window might also be used for this purpose. Previous work using the multi-angle data acquisition technique demonstrated its utility to determine source thermal emission. Here we find the multi-angle technique can be used to determine the source specular reflectivity to {approximately}0.05 if there is very good system performance (NETD {approx} 0.01 K).
3 citations
17 Oct 1994
TL;DR: In this article, an extensive modeling of the rms error of determining a ground temperature and emissivity for a gray body has been performed as a function of integration time, spectroscopic resolution of the system, ground emissivities, atmospheric variables, and atmospheric data accuracy.
Abstract: TAISIR, temperature and imaging system infrared, is a nominally satellite based platform for remote sensing of the earth. One of its design features is to acquire atmospheric data simultaneous with ground data, resulting in minimal dependence on external atmospheric models for data correction. Extensive modeling of the rms error of determining a ground temperature and emissivity for a gray body has been performed as a function of integration time, spectroscopic resolution of the system, ground emissivity, atmospheric variables, and atmospheric data accuracy. We find that increased resolution improves measurement accuracy by emphasizing those regions where the atmospheric transmission is highest and atmospheric emission/absorption lowest. We find rms temperature errors
2 citations
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TL;DR: In this article, a correction procedure was proposed in which the surface is alternately viewed normally and at an angle near 60° from the normal; the difference between the two measurements was shown to give the required correction.
Abstract: Measurements made with an airborne radiation thermometer suffer from the imperfect transparency of the atmosphere and the nonblackness of the sea surface. A correction procedure is proposed in which the surface is alternately viewed normally and at an angle near 60° from the normal; the difference between the two measurements is shown to give the required correction. Field tests indicate that an absolute accuracy of ±0.2°C in estimates of surface temperature can be achieved.
118 citations
TL;DR: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented in this paper, which relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N.
Abstract: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented. This method relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N. Extrapolating the two air mass observations to zero air mass is shown to give a value of the temperature in good agreement with the true sea surface temperature. A discussion concerning the viewing angles is presented.
66 citations
TL;DR: Using lowtran and the multiple-altitude method, calibration of thermograms to account for atmospheric effects yields computed surface temperatures within 0.7°C of concurrent kinetic temperature readings.
Abstract: Airborne measurements of atmospheric-path transmission and atmospheric-path (upwelled) radiance in the 8–14-μm band were obtained by applying a multiple altitude and a dual-view angle calibration technique to thermal IR line scanner data. A spectrally corrected lowtran code was used to generate path transmission and upwelled radiance values corresponding to the empirical measurements. Using lowtran and the multiple-altitude method, calibration of thermograms to account for atmospheric effects yields computed surface temperatures within 0.7°C of concurrent kinetic temperature readings. The angular calibration method results in similar computed surface temperature errors for 304.8-m (1000-ft) altitude data and increasing by 1.2°C/304.8-m up to a 1828.8-m (6000-ft) altitude. This paper contains results of a comparative analysis of these approaches for atmospheric calibration.
37 citations
TL;DR: Accuracies attainable through the use of the double viewing angle method appear to be similar to those from more complex techniques for many atmospheric conditions.
Abstract: This paper presents a passive method for computation of thermal IR transmittance over slant paths. This double viewing angle technique utilizes data gathered by a radiometer or imager carried by a manned or unmanned aircraft. A sensitivity analysis showed the effect of changes or errors in input parameters on calculated transmittances. The analysis suggested the applicability and limitations of this method. Accuracies attainable through the use of the double viewing angle method appear to be similar to those from more complex techniques for many atmospheric conditions.
7 citations
01 Jan 1992
Abstract: Statistical estimation problems of atmospheric correction techniques for thermal infrared imagery have been studied. A revised multipleview-angle atmospheric correction technique has been developed and tested using the LOWTRAN radiative transfer model as truth. Its average absolute temperature prediction accuracy for an independent data set is 0.8 K for long-wave infrared imagery and 1.0 K for mid-wave infrared imagery, when error-free data are assumed. The benefit of robust, resistant regression estimators was studied using Monte Carlo simulations having real-world measurement errors and data outliers. An error propagation analysis showed that 1.0-3.3 K of rms error is likely given reasonable data set sizes and robust estimators.
4 citations