Relevant bibliographies by topics / Radiance image simulator

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Radiance image simulator'

Author: Grafiati
Published: 14 March 2023

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Journal articles on the topic "Radiance image simulator"

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Gouvello, Alix de, Laurent Soulier, and Antoine Dupret. "From the radiance reflected by a scene to a digital picture : a compact model based simulator for image sensor design." Electronic Imaging 2020, no. 7 (January 26, 2020): 329–1. http://dx.doi.org/10.2352/issn.2470-1173.2020.7.iss-329.

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In order to explore the design space of a new, potentially unconventional, sensor or to optimize sensor characteristics for a given computer vision application, an image acquisition process simulator has been designed. Its aim is to be simple and modular, yet complete and accurate enough to match the physical phenomena involved. The approach has been described in this paper to highlight the different steps of the acquisition process and to explain the implementation choices and the hypotheses that were made. The simulator has been tested on images of point sources, on simulated test patterns and on real high definition pictures and has proven realistic.
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Zahidi, Usman A., Peter W. T. Yuen, Jonathan Piper, and Peter S. Godfree. "An End-to-End Hyperspectral Scene Simulator with Alternate Adjacency Effect Models and Its Comparison with CameoSim." Remote Sensing 12, no. 1 (December 24, 2019): 74. http://dx.doi.org/10.3390/rs12010074.

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In this research, we developed a new rendering-based end to end Hyperspectral scene simulator CHIMES (Cranfield Hyperspectral Image Modelling and Evaluation System), which generates nadir images of passively illuminated 3-D outdoor scenes in Visible, Near Infrared (NIR) and Short-Wave Infrared (SWIR) regions, ranging from 360 nm to 2520 nm. MODTRAN TM (MODerate resolution TRANsmission), is used to generate the sky-dome environment map which includes sun and sky radiance along with the polarisation effect of the sky due to Rayleigh scattering. Moreover, we perform path tracing and implement ray interaction with medium and volumetric backscattering at rendering time to model the adjacency effect. We propose two variants of adjacency models, the first one incorporates a single spectral albedo as the averaged background of the scene, this model is called the Background One-Spectra Adjacency Effect Model (BOAEM), which is a CameoSim like model created for performance comparison. The second model calculates background albedo from a pixel’s neighbourhood, whose size depends on the air volume between sensor and target, and differential air density up to sensor altitude. Average background reflectance of all neighbourhood pixel is computed at rendering time for estimating the total upwelled scattered radiance, by volumetric scattering. This model is termed the Texture-Spectra Incorporated Adjacency Effect Model (TIAEM). Moreover, for estimating the underlying atmospheric condition MODTRAN is run with varying aerosol optical thickness and its total ground reflected radiance (TGRR) is compared with TGRR of known in-scene material. The Goodness of fit is evaluated in each iteration, and MODTRAN’s output with the best fit is selected. We perform a tri-modal validation of simulators on a real hyperspectral scene by varying atmospheric condition, terrain surface models and proposed variants of adjacency models. We compared results of our model with Lockheed Martin’s well-established scene simulator CameoSim and acquired Ground Truth (GT) by Hyspex cameras. In clear-sky conditions, both models of CHIMES and CameoSim are in close agreement, however, in searched overcast conditions CHIMES BOAEM is shown to perform better than CameoSim in terms of ℓ 1 -norm error of the whole scene with respect to GT. TIAEM produces better radiance shape and covariance of background statistics with respect to Ground Truth (GT), which is key to good target detection performance. We also report that the results of CameoSim have a many-fold higher error for the same scene when the flat surface terrain is replaced with a Digital Elevation Model (DEM) based rugged one.
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Román, R., M. Antón, A. Cazorla, A. de Miguel, F. J. Olmo, J. Bilbao, and L. Alados-Arboledas. "Calibration of an all-sky camera for obtaining sky radiance at three wavelengths." Atmospheric Measurement Techniques Discussions 5, no. 1 (February 23, 2012): 1873–905. http://dx.doi.org/10.5194/amtd-5-1873-2012.

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Abstract. This paper proposes a method to obtain spectral sky radiances, at three wavelengths (464, 534 and 626 nm), from hemispherical sky images. Images are registered with an All-Sky Imager installed at the Andalusian Center for Environmental Research (CEAMA) in Granada (Spain). The methodology followed in this work for the absolute calibration in radiance of this instrument is based on the comparison of its output measurements with modelled sky radiances derived from the Libradtran/UVSPEC radiative transfer code under cloud-free conditions. Previously, in order to check the goodness of the simulated radiances, these are compared with experimental values recorded by a CIMEL sunphotometer. In general, modelled radiances are in agreement with experimental data, showing mean differences lower than 15% except for the pixels located next to the sun position that show larger errors. The comparison between the output signal of the All-Sky Imager and the modelled sky radiances provides a calibration matrix for each image. The variability of the matrix coefficients is analyzed, showing no significant changes along a period of 5 months. Therefore, a unique calibration matrix per channel is obtained for all selected images (a total of 705 images per channel). Camera radiances are compared with CIMEL radiances, finding mean absolute differences between 2% and 15% except for pixels near to the Sun and high zenith angles. We apply these calibration matrices to three images in order to study the sky radiance distributions for three different sky conditions: cloudless, overcast and partially cloudy. Horizon brightening under cloudless conditions has been observed together with the enhancement effect of individual clouds on sky radiance.
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Román, R., M. Antón, A. Cazorla, A. de Miguel, F. J. Olmo, J. Bilbao, and L. Alados-Arboledas. "Calibration of an all-sky camera for obtaining sky radiance at three wavelengths." Atmospheric Measurement Techniques 5, no. 8 (August 21, 2012): 2013–24. http://dx.doi.org/10.5194/amt-5-2013-2012.

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Abstract. This paper proposes a method to obtain spectral sky radiances, at three wavelengths (464, 534 and 626 nm), from hemispherical sky images. Images are registered with the All-Sky Imager installed at the Andalusian Center for Environmental Research (CEAMA) in Granada (Spain). The methodology followed in this work for the absolute calibration in radiance of this instrument is based on the comparison of its output measurements with modelled sky radiances derived from the LibRadtran/UVSPEC radiative transfer code under cloud-free conditions. Previously, in order to check the goodness of the simulated radiances, these are compared with experimental values recorded by a CIMEL sunphotometer. In general, modelled radiances are in agreement with experimental data, showing mean differences lower than 20% except for the pixels located next to the Sun position that show larger errors. The relationship between the output signal of the All-Sky Imager and the modelled sky radiances provides a calibration matrix for each image. The variability of the matrix coefficients is analyzed, showing no significant changes along a period of 5 months. Therefore, a unique calibration matrix per channel is obtained for all selected images (a total of 705 images per channel). Camera radiances are compared with CIMEL radiances, finding mean absolute differences between 2% and 15% except for pixels near to the Sun and high scattering angles. We apply these calibration matrices to three images in order to study the sky radiance distributions for three different sky conditions: cloudless, overcast and partially cloudy. Horizon brightening under cloudless conditions has been observed together with the enhancement effect of individual clouds on sky radiance.
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Ионова, Е. А., and Н. Ю. Давидюк. "Исследование фокусирующих свойств концентратора фотоэлектрического модуля в расширенном температурном диапазоне." Журнал технической физики 93, no. 1 (2023): 122. http://dx.doi.org/10.21883/jtf.2023.01.54071.160-22.

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Abstract: In the current work properties of a solar radiance concentrator with Fresnel lens made of Elastosil RT604 silicon made by Wacker have been investigated. The dependence of concentrator focal distance on temperature has been determined. Impact of variation of temperature-dependent concentrator focusing properties on the magnitude of short current of photovoltaic submodule has been determined by direct measurements using solar simulator. Using formalized model of modules based on the studied concentrator and solar cells with three and six p-n junctions dimensions of a solar image in a wavelength range corresponding to an absorption profile of individual p-n junctions has been calculated for the temperature range 10-60 C. It has been concluded that in the case of three p-n junctions the minimum size of solar image at focal plane was 4.7 mm with the distance between the concentrator and solar cell being equal to 106.25 mm, and in the case of six p-n junctions, the minimum size was 4.8 mm with the distance between concentrator and solar cell being equal to 106.5 mm.
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Antuña-Sánchez, Juan C., Roberto Román, Victoria E. Cachorro, Carlos Toledano, César López, Ramiro González, David Mateos, Abel Calle, and Ángel M. de Frutos. "Relative sky radiance from multi-exposure all-sky camera images." Atmospheric Measurement Techniques 14, no. 3 (March 22, 2021): 2201–17. http://dx.doi.org/10.5194/amt-14-2201-2021.

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Abstract. All-sky cameras are frequently used to detect cloud cover; however, this work explores the use of these instruments for the more complex purpose of extracting relative sky radiances. An all-sky camera (SONA202-NF model) with three colour filters narrower than usual for this kind of cameras is configured to capture raw images at seven exposure times. A detailed camera characterization of the black level, readout noise, hot pixels and linear response is carried out. A methodology is proposed to obtain a linear high dynamic range (HDR) image and its uncertainty, which represents the relative sky radiance (in arbitrary units) maps at three effective wavelengths. The relative sky radiances are extracted from these maps and normalized by dividing every radiance of one channel by the sum of all radiances at this channel. Then, the normalized radiances are compared with the sky radiance measured at different sky points by a sun and sky photometer belonging to the Aerosol Robotic Network (AERONET). The camera radiances correlate with photometer ones except for scattering angles below 10∘, which is probably due to some light reflections on the fisheye lens and camera dome. Camera and photometer wavelengths are not coincident; hence, camera radiances are also compared with sky radiances simulated by a radiative transfer model at the same camera effective wavelengths. This comparison reveals an uncertainty on the normalized camera radiances of about 3.3 %, 4.3 % and 5.3 % for 467, 536 and 605 nm, respectively, if specific quality criteria are applied.
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Clerbaux, N., S. Dewitte, C. Bertrand, D. Caprion, B. De Paepe, L. Gonzalez, A. Ipe, and J. E. Russell. "Unfiltering of the Geostationary Earth Radiation Budget (GERB) Data. Part II: Longwave Radiation." Journal of Atmospheric and Oceanic Technology 25, no. 7 (July 1, 2008): 1106–17. http://dx.doi.org/10.1175/2008jtecha1002.1.

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Abstract The method used to estimate the unfiltered longwave broadband radiance from the filtered radiances measured by the Geostationary Earth Radiation Budget (GERB) instrument is presented. This unfiltering method is used to generate the first released edition of the GERB-2 dataset. This method involves a set of regressions between the unfiltering factor (i.e., the ratio of the unfiltered and filtered broadband radiances) and the narrowband observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument. The regressions are theoretically derived from a large database of simulated spectral radiance curves obtained by radiative transfer computations. The generation of this database is fully described. Different sources of error that may affect the GERB unfiltering have been identified and the associated error magnitudes are assessed on the database. For most of the earth–atmosphere conditions, the error introduced during the unfiltering processes is well under 0.5% (RMS error of about 0.1%). For more confidence, the unfiltered radiances of GERB-2 are validated by cross comparison with collocated and coangular Clouds and the Earth’s Radiant Energy System (CERES) observations. The agreement between the unfiltered radiances is within the science goals (1% accuracy for GERB and 0.5% for CERES) for the Flight Model 2 (FM2). For the CERES Flight Model 3 (FM3) instrument, an overall difference of 1.8% is observed. The intercomparisons indicate some scene-type dependency, which is due to the unfiltering for the cloudy scenes. This should be corrected for subsequent editions of the database.
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Clerbaux, N., S. Dewitte, C. Bertrand, D. Caprion, B. De Paepe, L. Gonzalez, A. Ipe, J. E. Russell, and H. Brindley. "Unfiltering of the Geostationary Earth Radiation Budget (GERB) Data. Part I: Shortwave Radiation." Journal of Atmospheric and Oceanic Technology 25, no. 7 (July 1, 2008): 1087–105. http://dx.doi.org/10.1175/2007jtecha1001.1.

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Abstract The method used to estimate the unfiltered shortwave broadband radiance from the filtered radiances measured by the Geostationary Earth Radiation Budget (GERB) instrument is presented. This unfiltering method is used to generate the first released edition of the GERB-2 dataset. The method involves a set of regressions between the unfiltering factor (i.e., the ratio of the unfiltered and filtered broadband radiances) and the narrowband observations of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument. The regressions are theoretically derived from a large database of simulated spectral radiance curves obtained by radiative transfer computations. The generation of the database is fully described. Different sources of error that may affect the GERB unfiltering have been identified and the associated error magnitudes are assessed on this database. For most of the earth–atmosphere conditions, the error introduced during the unfiltering process is below 1%. In some conditions (e.g., low sun elevation above the horizon) the error can present a higher relative value, but the absolute error value remains well under the accuracy goal of 1% of the full instrument scale (2.4 W m−2 sr−1). To increase the confidence level, the edition 1 unfiltered radiances of GERB-2 are validated by cross comparison with collocated and coangular Clouds and the Earth’s Radiant Energy System (CERES) observations for different scene types. In addition to an overall offset between the two instruments, the intercomparisons indicate a scene-type dependency up to 4% in unfiltered radiance. Further studies are required to confirm the cause, but an insufficiently accurate characterization of the shortwave spectral response of the GERB instrument in the visible part of the spectrum is one area under further investigation.
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Dandini, Paolo, Céline Cornet, Renaud Binet, Laetitia Fenouil, Vadim Holodovsky, Yoav Y. Schechner, Didier Ricard, and Daniel Rosenfeld. "3D cloud envelope and cloud development velocity from simulated CLOUD (C3IEL) stereo images." Atmospheric Measurement Techniques 15, no. 20 (October 27, 2022): 6221–42. http://dx.doi.org/10.5194/amt-15-6221-2022.

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Abstract. A method to derive the 3D cloud envelope and the cloud development velocity from high spatial and temporal resolution satellite imagery is presented. The CLOUD instrument of the recently proposed C3IEL mission lends itself well to observing at high spatial and temporal resolutions the development of convective cells. Space-borne visible cameras simultaneously image, under multiple view angles, the same surface domain every 20 s over a time interval of 200 s. In this paper, we present a method for retrieving cloud development velocity from simulated multi-angular, high-resolution top of the atmosphere (TOA) radiance cloud fields. The latter are obtained via the image renderer Mitsuba for a cumulus case generated via the atmospheric research model SAM and via the radiative transfer model 3DMCPOL, coupled with the outputs of an orbit, attitude, and camera simulator for a deep convective cloud case generated via the atmospheric research model Meso-NH. Matching cloud features are found between simulations via block matching. Image coordinates of tie points are mapped to spatial coordinates via 3D stereo reconstruction of the external cloud envelope for each acquisition. The accuracy of the retrieval of cloud topography is quantified in terms of RMSE and bias that are, respectively, less than 25 and 5 m for the horizontal components and less than 40 and 25 m for the vertical components. The inter-acquisition 3D velocity is then derived for each pair of tie points separated by 20 s. An independent method based on minimising the RMSE for a continuous horizontal shift of the cloud top, issued from the atmospheric research model, allows for the obtainment of a ground estimate of the velocity from two consecutive acquisitions. The mean values of the distributions of the stereo and ground velocities exhibit small biases. The width of the distributions is significantly different, with higher a distribution width for the stereo-retrieved velocity. An alternative way to derive an average velocity over 200 s, which relies on tracking clusters of points via image feature matching over several acquisitions, was also implemented and tested. For each cluster of points, mean stereo and ground positions were derived every 20 s over 200 s. The mean stereo and ground velocities, obtained as the slope of the line of best fit to the mean positions, are in good agreement.
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Wang, Yuye, Guofeng Zhang, and Xiaoguang Hu. "Large-scale scene real-time infrared simulation based on texture blending." International Journal of Intelligent Computing and Cybernetics 9, no. 4 (November 14, 2016): 406–15. http://dx.doi.org/10.1108/ijicc-07-2016-0024.

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Purpose Infrared simulation plays an important role in small and affordable unmanned aerial vehicles. Its key and main goal is to get the infrared image of a specific target. Infrared physical model is established through a theoretical research, thus the temperature field is available. Then infrared image of a specific target can be simulated properly while taking atmosphere state and effect of infrared imaging system into account. For recent years, some research has been done in this field. Among them, the infrared simulation for large scale is still a key problem to be solved. In this passage, a method of classification based on texture blending is proposed and this method effectively solves the problem of classification of large number of images and increase the frame rate of large infrared scene rendering. The paper aims to discuss these issues. Design/methodology/approach Mosart Atmospheric Tool (MAT) is used first to calculate data of sun radiance, skyshine radiance, path radiance, temperatures of different material which is an offline process. Then, shader in OGRE does final calculation to get simulation result and keeps a high frame rate. Considering this, the authors convert data in MAT file into textures which can be easily handled by shader. In shader responding, radiance can be indexed by information of material, vertex normal, eye and sun. Adding the effect of infrared imaging system, the final radiance distribution is obtained. At last, the authors get infrared scene by converting radiance to grayscale. Findings In the fragment shader, fake infrared textures are used to look up temperature which can calculate radiance of itself and related radiance. Research limitations/implications The radiance is transferred into grayscale image while considering effect of infrared imaging system. Originality/value Simulation results show that a high frame rate can be reached while guaranteeing the fidelity.
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Dissertations / Theses on the topic "Radiance image simulator"

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DI, NINNI PAOLA. "A statistical method for the retrieval of the Solar Induced Fluorescence of vegetation by means of radiance spectra from space: fundamentals, performance and robustness analysis." Doctoral thesis, Università di Siena, 2017. http://hdl.handle.net/11365/1013500.

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During the last decade, a growing interest has arisen in the Solar Induced Fluorescence (SIF) emitted by terrestrial plants, with particular reference to the development of new methods for its retrieval from satellite data. This could pave the way to the monitoring of vegetation SIF at a global scale and its exploitation as a key parameter of dynamical global vegetation models used for carbon cycle studies. Besides, SIF retrieval from satellite could greatly contribute to the monitoring of the health status of vegetation with relation to several environmental stress factors. In this PhD thesis, a new method for the retrieval of the SIF of vegetation is proposed. The method is based on a statistical approach and it was developed in order to overcome some limits that typically affect the methods proposed up to now and that can affect the accuracy of the retrieved SIF. Specifically, this method provides as output both the SIF spectrum and the in-band averaged or integrated SIF intensity from the top of atmosphere radiance spectra measured by means of a passive remote sensing technique. In detail, in this PhD thesis the fundamentals of the proposed method have been discussed from a mathematical point of view and the implementation has been accurately described. Besides, performance assessment and robustness analysis of the ML-SIF method have been also carried out. The lack of both spectra of reflectance and SIF at canopy level for several vegetation species and the related SIF radiance spectra prevented the direct implementation of the learning procedure with actual measurements. As a consequence, this study relied on the use of a tool Soil Canopy Observation, Photochemistry and Energy Balance (SCOPE) and an in-house developed radiance image simulator. The latter has been specifically implemented during this work to simulate realistic radiance spectra containing SIF contributions.
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Vévoda, Petr. "Robust light transport simulation in participating media." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-336720.

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Light transport simulation is used in realistic image synthesis to create physically plausible images of virtual scenes. Important components of the scenes are participating media (e.g. air, water, skin etc.). Efficient computation of light transport in participating media robust to their large diversity is still an open problem. We implemented the UPBP algorithm recently developed by Křivánek et al. It addresses the problem by combining several complementary previous methods using multiple importance sampling, and excels at rendering scenes where the previous methods alone fail. The implementation is available online, we focused on its thorough description to facilitate and support further research in this field. Powered by TCPDF (www.tcpdf.org)
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Book chapters on the topic "Radiance image simulator"

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Liu, Dong, Yanbing Dong, and Hongxia Mao. "Top-of-Atmosphere Radiance Image Simulation from the Visible to Thermal Infrared." In Proceedings of the 7th China High Resolution Earth Observation Conference (CHREOC 2020), 419–35. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-5735-1_31.

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Conference papers on the topic "Radiance image simulator"

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Kim, Hongsuk H. "Atmospheric Correction Algorithm of Real and Simulated Space Imagery Using Radiative Transfer Code." In Laser and Optical Remote Sensing: Instrumentation and Techniques. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/lors.1987.tuc8.

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An image processing algorithm which can be used not only to simulate satellite mulitispectral imagery but also to derive surface reflectance from satellite imagery is being developed. In essence, the algorithm is a pixel by pixel modelling of the atmospheric radiance which can be either added to a simulated ground scene or subtracted from space data.
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Schneider, F. D., T. Yin, J. P. Gastellu-Etchegorry, F. Morsdorf, and M. E. Schaepman. "At-sensor radiance simulation for airborne imaging spectroscopy." In 2014 6th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS). IEEE, 2014. http://dx.doi.org/10.1109/whispers.2014.8077586.

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Li, Zhuoluo, Bin Liang, Tao Zhang, and Hailong Zhu. "Image simulation for airborne star tracker under strong background radiance." In 2012 IEEE International Conference on Computer Science and Automation Engineering (CSAE). IEEE, 2012. http://dx.doi.org/10.1109/csae.2012.6272676.

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Liu, Dong, Jing Ma, and Hongxia Mao. "Remote sensing radiance image simulation of the non-Lambertian land surface." In Eighth Symposium on Novel Photoelectronic Detection Technology and Applications, edited by Shining Zhu, Qifeng Yu, Junhong Su, Lianghui Chen, and Junhao Chu. SPIE, 2022. http://dx.doi.org/10.1117/12.2619527.

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"Radiant Image-Based Data Post-Processing and Simulation." In 2018 Symposium on Simulation for Architecture and Urban Design. Society for Modeling and Simulation International (SCS), 2018. http://dx.doi.org/10.22360/simaud.2018.simaud.032.

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Zhang, Yin, Shi-jing Hao, Ming-yu Cong, and Yi-ming Cao. "A simulation method of 3D cirrus radiance images for space-based missile warning detectors." In 2014 7th International Congress on Image and Signal Processing (CISP). IEEE, 2014. http://dx.doi.org/10.1109/cisp.2014.7003839.

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Basov, Alexander, George Boos, Vladimir Budak, and Anton Grimailo. "Modelling Reflection from Real Surfaces." In 31th International Conference on Computer Graphics and Vision. Keldysh Institute of Applied Mathematics, 2021. http://dx.doi.org/10.20948/graphicon-2021-3027-800-808.

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Modelling Reflection from Real Surfaces Alexander Basov 1, George Boos 1, Vladimir Budak 1 and Anton Grimailo 1 1 National Research University "Moscow Power Engineering Institute", Krasnokazarmennaya 17, Moscow, 111250, Russia Abstract The article is devoted to modelling the reflection of radiation from real surfaces. Most of the existing models consider only the near-surface processes, although in reality the processes occurring in the volume of the layer also have a fairly significant contribution to the final radiance. The authors propose a mathematical model that takes into account volume scattering. The model is based on the radiative transfer equation, the numerical solution of which makes it possible to find the reflection and transmission radiance factors. The paper describes the features of the implementation of the model in the case of a multilayer medium, a method is proposed that makes it possible to consider the effect of a randomly uneven surface. To validate the model, calculations of the radiance of the reflected radiation from the asphalt concrete pavement were carried out: for this, the corresponding parameters were selected that describe the optical properties of the medium. A comparison of the simulation results with the results of measuring the radiative characteristics of an asphalt concrete pavement sample was carried out, which showed that the model gives sufficiently reliable results not only qualitatively, but also quantitatively. The created model allows high-speed calculations of the radiative characteristics of various surfaces for different angles of incidence and observation, which can be used both in lighting calculations and in the formation of realistic images in computer graphics.
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Moukalled, F., N. Ghaddar, H. Kabbani, N. Khaled, and Z. Fawaz. "Numerical and Experimental Investigation of Thermal Signatures of Buried Landmines in Dry Soil." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72304.

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This paper reports a numerical and experimental investigation conducted to study the surface thermal signature of buried landmines. Numerical predictions are obtained by solving an unsteady three-dimensional energy balance model for heat transport in dry soil with a buried mine using the conservative finite-volume method. The model is validated by comparing generated results against published analytical and numerical data in addition to indoor measurements performed on dry soil inside an environmental chamber. The thermal signatures are observed while cooling takes place after exposing the soil surface to a radiant heat flux for a specified period. Transient temperature profiles produced numerically agree well with thermocouple measurements recorded at shallow soil depths and with surface IR images. The difference between predicted and measured surface temperatures is less than 0.4°C and the difference in thermal signature is less than 0.3°C. Sit in. The numerical model is also used to predict perturbations of the expected thermal signatures that are compared to the real (measured) ones from the IR images. The thermographic analysis shows good promise as a method for detecting shallowly buried land mines where not only the temperature difference or contrast images generated by the thermal signatures are matched between the IR images and the simulation images with high accuracy, but also the absolute temperatures for many images generated at discrete time intervals.
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Srinivasa Ramanujam, K., and C. Balaji. "A Fast Polarized Microwave Radiative Transfer Model for a Raining Atmosphere." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22228.

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Retrieval of vertical rain structure and hence the estimation of surface rain rate is of central importance to various missions involving remote sensing of the earth’s atmosphere. Typically, remote sensing involves scanning the earth’s atmosphere at visible, infra red and microwave frequencies. While the visible and infra red frequencies can scan the atmosphere with higher spatial resolution, they are not suited for scanning under cloudy conditions as clouds are opaque under these frequencies. However, the longer wavelength microwave radiation can partially penetrate through the clouds without much attenuation thereby making it more suitable for meteorological purposes. The retrieval algorithms used for passive microwave remote sensing involve modeling of the radiation in the earth’s atmosphere where in the clouds and precipitating rain (also known as hydrometeors) emit / absorb / scatter. Additionally, it has been observed that the rain droplets tend to polarize the microwave signal emitted by the earth’s surface. In view of this, the first step in the development of a rainfall retrieval algorithm for any satellite mission is to simulate the radiances (also known as brightness temperatures) that would have been measured by a typical radiometer for different sensor frequencies and resolutions. Towards this, a polarized microwave radiation transfer code has been developed in house for a plane parallel raining atmosphere (henceforth called as forward model) that depicts the physics as seen by a satellite. Physics based retrieval algorithm often involves repeated execution of the forward model for various raining scenario. However, due to the complexity involved in the radiation modeling of the raining atmosphere which is participating in nature, the forward model suffers from the drawback that it requires enormous computational effort. In the present work, a much quicker alternative is proposed wherein the forward model can be replaced with an Artificial Neural Network (ANN) based Fast Forward Model (AFFM). This AFFM can be used in conjunction with an appropriate inverse technique to retrieve the rain structure. Spectral microwave brightness temperatures at frequencies corresponding to the Tropical Rainfall Measuring Mission (TRMM) of National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) are first simulated using an in-house polarized radiate on transfer code for sixteen past cyclones in the North Indian Ocean region in the period (2000–2005), using the hydrometeor profiles retrieved from the Goddard Profiling Algorithm (GPROF) of the Tropical Rainfall Measuring Mission (TRMM)’s Microwave Imager (TMI). This data is split into two sets: while the first set of data is used for training the network, the remainder of the data is used for testing the ANN. The results obtained are very encouraging and shows that neural network is capable of predicting the brightness temperature accurately with the correlation coefficient of over 99%. Furthermore, the execution of the forward model on an Intel Core 2 Quad 3.0 GHz processor based, 8 GB DDR3 RAM workstation took 3 days, while the AFFM delivers the results in 10 seconds.
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