Dr. Prabal Nandy Profile

Dr. Prabal Nandy

Distinguished Member of Technical Staff at Sandia National Labs

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Author

Publications (10)

Proceedings Article | 4 May 2007 Paper

Remote optical interrogation of radiation sensitive infrared polarizers

R. Boye, S. Kemme, P. Nandy, C. Washburn, S. Samora, S. Dirk, D. Wheeler

Proceedings Volume 6540, 65400C (2007) https://doi.org/10.1117/12.720014

KEYWORDS: Polymers, Polarizers, Gold, Polarization, Adhesives, Ionizing radiation, Polymer thin films, Etching, Infrared radiation, Wave plates

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Proceedings Article | 3 May 2007 Paper

Micropolarizer arrays in the MWIR for snapshot polarimetric imaging

S. Kemme, A. Cruz-Cabrera, P. Nandy, R. Boye, J. Wendt, T. Carter, S. Samora

Proceedings Volume 6556, 655604 (2007) https://doi.org/10.1117/12.720036

KEYWORDS: Polarizers, Polarization, Staring arrays, Polarimetry, Beam propagation method, Mid-IR, Signal attenuation, Refractive index, Infrared imaging, Infrared radiation

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Proceedings Article | 22 August 2005 Paper

Segmenting clouds from space: a hybrid multispectral classification algorithm for satellite imagery

Mark Wilson, Prabal Nandy, Brian Post, Jody Smith, Joseph Wehlburg

Proceedings Volume 5882, 58820I (2005) https://doi.org/10.1117/12.617656

KEYWORDS: Clouds, Image segmentation, Prototyping, Image classification, Infrared imaging, Long wavelength infrared, Signal to noise ratio, Satellites, Thermography, Algorithm development

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Proceedings Article | 12 August 2004 Paper

Edge-based correlation image registration algorithm for the Multispectral Thermal Imager (MTI)

Prabal Nandy, Brian Post, Jody Smith, Max Decker

Proceedings Volume 5425, (2004) https://doi.org/10.1117/12.541409

KEYWORDS: Image registration, Sensors, Image processing, Thermography, Multispectral imaging, Satellites, Prisms, Satellite imaging, Algorithm development, Image restoration

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Proceedings Article | 7 January 2004 Paper

Subpixel resolution with the multispectral thermal imager (MTI)

Prabal Nandy, Jody Smith, Max Decker

Proceedings Volume 5159, (2004) https://doi.org/10.1117/12.509759

KEYWORDS: Image processing, Point spread functions, Sensors, Satellites, Image resolution, Satellite imaging, Thermography, Radiometry, Bridges, Imaging systems

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Proceedings Article | 15 November 2000 Paper

Ground-reference techniques for the absolute radiometric calibration of MODIS

Kurtis Thome, Emily Whittington, Noel Smith, Prabal Nandy, Edward Zalewski

Proceedings Volume 4135, (2000) https://doi.org/10.1117/12.494219

KEYWORDS: Sensors, Calibration, MODIS, Reflectivity, Satellites, Sensor calibration, Radiometry, Landsat, Aerosols, Earth observing sensors

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Proceedings Article | 15 November 2000 Paper

Accuracy of ground-reference calibration of imaging spectroradiometers at large sensor view angles

Kurtis Thome, Prabal Nandy

Proceedings Volume 4132, (2000) https://doi.org/10.1117/12.406595

KEYWORDS: Aerosols, Sensors, Calibration, Reflectivity, Atmospheric modeling, Radiative transfer, Atmospheric particles, Atmospheric sensing, Absorption, Satellites

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Proceedings Article | 15 November 2000 Paper

Sensitivity analysis of a CCD-based camera system for the retrieval of bidirectional reflectance distribution function for vicarious calibration

Prabal Nandy, Kurtis Thome, Stuart Biggar

Proceedings Volume 4132, (2000) https://doi.org/10.1117/12.406597

KEYWORDS: Bidirectional reflectance transmission function, Data modeling, Atmospheric modeling, Calibration, Imaging systems, Reflectivity, CCD cameras, Cameras, Backscatter, Satellites

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Proceedings Article | 23 August 2000 Paper

Early ground-reference calibration results for Landsat 7 ETM+ using small test sites

Kurtis Thome, Emily Whittington, John LaMarr, Nik Anderson, Prabal Nandy

Proceedings Volume 4049, (2000) https://doi.org/10.1117/12.410334

KEYWORDS: Calibration, Reflectivity, Sensors, Landsat, Earth observing sensors, Radiative transfer, Absorption, Lamps, Aerosols, Ozone

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Proceedings Article | 28 December 1999 Paper

Laboratory characterization of a CCD camera system for retrieval of bi-directional reflectance distribution function

Prabal Nandy, Kurtis Thome, Stuart Biggar

Proceedings Volume 3870, (1999) https://doi.org/10.1117/12.373192

KEYWORDS: Bidirectional reflectance transmission function, Imaging systems, Cameras, Polarization, Point spread functions, Charge-coupled devices, Sensors, Data modeling, Calibration, CCD cameras

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The Remote Sensing Group of the Optical Science Center at the University of Arizona has developed a four-band, multi- spectral, wide-angle, imaging radiometer for the retrieval of the bi-directional reflectance distribution function (BRDF) for vicarious calibration applications. The system consists of a fisheye lens with four interference filters centered at 470 nm, 575 nm, 660 nm, and 835 nm for spectral selection and an astronomical grade 1024 X 1024-pixel, silicon CCD array. Data taken by the system fit in the array as a nominally 0.2 degree per pixel image. This imaging radiometer system has been used in support of the calibration of Landsat-5 and SPOT- satellite sensors. This paper presents the results of laboratory characterization of the system to determine linearity of the detector, point spread function (PSF) and polarization effects. The linearity study was done on detector array without the lens, using a spherical-integrating source with a 1.5-mm aperture. This aperture simulates a point source for distances larger than 60 cm. Data were collected as both a function of exposure time and distance from the source. The results of these measurements indicate that each detector of the array is linear to better than 0.5%. Assuming a quadratic response improves this fit to better than 0.1% over 88% of the upper end of the detector's dynamic range. The point spread function (PSF) of the lens system was measured using the sphere source and aperture with the full camera system operated at a distance of 700 mm from the source, thus the aperture subtends less than the field of view of one pixel. The PSF was measured for several field angles and the signal level was found to fall to less than 1% of the peak signal within 1.5-degrees (10 pixels) for the on-axis case. The effect of this PSF on the retrieval of modeled BRDFs is shown to be less than 0.2% out to view angles of 70 degrees. The final test presented is one to assess the polarization effects of the lens system by illuminating the camera system with the same spherical-integrating source with a 50-mm aperture with a linear polarizing filter. The degree of polarization of the system is shown to be negligible for on-axis imaging but to have up to a 20% effect for field angles of 70 degrees. The effect of the system polarization on the retrieval of modeled BRDFs is shown to be up to 3% for field angles of 70 degrees off nadir and solar zenith angle of 70 degrees. Polarization response is therefore found to be the greatest source of error in the system. A method to account for polarization effects in digital camera imagery is proposed.

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