Mr. Clyde H. Spencer Profile

Clyde H. Spencer

Remote Sensing Scientist at BAE Systems Inc

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Author

Publications (3)

Proceedings Article | 13 August 2010 Paper

Improved panchromatic sharpening of multi-spectral image data

Christoph Borel, Ronald Tuttle, Clyde Spencer

Proceedings Volume 7812, 78120G (2010) https://doi.org/10.1117/12.863110

KEYWORDS: Near infrared, Multispectral imaging, RGB color model, Point spread functions, Vegetation, Image restoration, Image quality, Image fusion, Radiometry, Image resolution

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Proceedings Article | 2 April 2008 Paper

Utility of polarimetric imagery as ancillary data for thematic classification as predicted by using measures of spectral separability

Clyde Spencer

Proceedings Volume 6972, 69720F (2008) https://doi.org/10.1117/12.772036

KEYWORDS: Landsat, Polarimetry, Polarization, Vegetation, Image classification, Aerospace engineering, Scene classification, Sensors, Distance measurement, Earth observing sensors

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Proceedings Article | 1 September 2006 Paper

Atmospheric correction of airborne POLDER polarimetric imagery using vectorized 6S

Christoph Borel, Clyde Spencer

Proceedings Volume 6302, 63020T (2006) https://doi.org/10.1117/12.680814

KEYWORDS: Polarization, Sensors, Atmospheric corrections, Polarimetry, Scattering, Reflectivity, Sun, Optical filters, Aerosols, Image filtering

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We are interested in using wide-field-of-view polarimetric imagers such as airborne POLDER (LOA, University of Lille) and AMPI (NASA) to study polarization signatures of surface targets. The airborne POLDER instrument has a field of view +/- 43° in along-track and +/- 51° cross-track. It records imagery through a rotating filter wheel with spectral filters, and in two spectral bands with linear polarization filters orientated at 0°, 60°, and 120° while flying at 70 m/s, generating images that need to be registered before spectra or the Stokes vectors can be computed. The atmospheric contributions, particularly in the short-wavelength visible bands, are anisotropic due to the scattering from molecules and aerosols, and the contrast is quite low, making automated image registration impossible. Thus, it is necessary to remove the polarized upwelling atmospheric contributions from the at-sensor radiances before the images can be registered, and target-leaving Stokes parameters can be derived. We accomplished the atmospheric correction by using the recently released vectorized version of the Second Simulation of the Satellite Signal in the Solar Spectrum (6Sv) from Eric Vermote et al. 1997. We wrote a front-end in IDL to run 6Sv over a range of viewing zenith and azimuth angles. The resulting Stokes parameters are then interpolated to a grid of input viewing coordinates for the sensor. Next, the Stokes hemispherical path radiances are converted to match the data of the airborne POLDER instrument for the linear polarization angles of 0°, 60°, and 120°. The upwelling atmospheric intensities are subtracted from the respective polarimetric intensity images and the difference is divided by the transmission multiplied with the solar irradiance. This atmospheric correction significantly reduces the low-frequency variations in intensity in the images resulting from atmospheric scattering. The atmospherically corrected intensity images at 0°, 60°, and 120° are then used to calculate the Stokes parameter images in the usual fashion. From the Stokes parameter images we calculate the degree and azimuth of linear polarization images for the surface.

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