Exelis Inc.

Itt Manufacturing Enterprises, Inc.

Kenneth K Ellis

Richard David Forkert

Paul C Griffith

Measuring the polarimetric response of an optical instrument includes the steps of: emitting light along an optical axis; receiving the light through first and second polarizers; and detecting the light received through the first and second polarizers, using a filter and a detector. A first set of measurements is obtained by measuring the intensity of light received through the first and second polarizers. A second set of measurements is obtained by placing an optical instrument along the optical axis in lieu of the filter and detector; and measuring the intensity of light received through the first polarizer, after the second polarizer has been removed. A third set of measurements is obtained using the optical instrument but having the second polarizer replace the first polarizer. The optical instrument may be characterized using the first, second and third sets of measurements. The characterization is completed without having to know the extinction ratios and the transmittance parameters of the polarizers.

System and method for characterizing polarimetric response of a remote sensing instrument

A line scanner scans in a cross track direction and moves forward on a platform in an along track direction. The line scanner includes a plurality of detectors forming a left array and a plurality of detectors forming a right array. The left array and the right array are tilted away from a line formed in the along track direction. The left array is configured to detect scene radiance from a surface of an object when the line scanner is scanning the surface on the right side of the line formed in the along track direction. The right array is configured to detect scene radiance from the surface of the object when the line scanner is scanning the surface to the left side of the line formed in the along track direction. The detectors in each respective array are configured to simultaneously detect the scene radiance.

System architecture for a constant footprint, constant GSD, constant spatial resolution linescanner

A method of determining slope of pixel intensities in an image includes the following steps: (a) receiving, from an imaging device, input pixel samples of a region of interest; (b) forming an impulse response function (IPR) for use in resampling the input pixel samples into output pixel intensities; and (c) calculating a derivative of the IPR. Also included is the step of convolving the derivative of the IPR with the input pixel samples to determine the slope of the output pixel intensities in the region of interest. In addition, the input pixel samples are generated in a first coordinate system by the imaging device, and the output pixel intensities are generated in a second coordinate system.

Algorithm for calculating high accuracy image slopes

A method of adaptive downsampling includes the steps of: (a) receiving input data having a first spatial resolution and a first grid spacing; (b) resampling the input data using an automatically adjustable kernel; and (c) providing output data having a second spatial resolution and a second grid spacing. The second spatial resolution, advantageously, is substantially constant across the second grid spacing. The input data may include image data, and the output data may include resampled, or downsampled image data. The image data may be images of the Earth at a first spatial resolution and a first grid spacing; the output data may be resampled data of the images of the Earth at a second spatial resolution and a second grid spacing.

Algorithm for adaptive downsampling to an irregular grid

A star sensor includes (a) a scan mirror for scanning at least one star; (b) a detector array, coupled to the scan mirror, for detecting the one star; and (c) a processor, coupled to the detector array. The processor includes a first filter configured to reduce noise spikes in the detected one star, and provide a detection mask of filtered data. Also included is a second filter configured to reduce non-contiguous samples in the detection mask. A centroid calculator is included to determine a location of the one star, after the first and second filtering. The first filter includes a median filter, followed by an averaging filter, both configured to filter the one star in an along-scan direction of the scan mirror. The first filter includes another median filter, which is configured to filter the detected one star in the cross-scan direction of the scan mirror. An adder is included to subtract (a) output data from the other median filter from (b) output data from the averaging filter and provide filtered star data to the second filter.

Star sensing for an earth imaging sensor

A method of lossless image data compression including the steps of: (a) receiving an image; (b) forming a residual image by differencing adjacent samples of the received image; (c) forming multiple bitplanes directly from the residual image; (d) predicting polarities of data values of the residual image; (e) determining incorrectly predicted polarities and storing the incorrectly predicted polarities in a table; (f) encoding each of the bitplanes and the incorrectly predicted polarities of the table to form a compressed image, and (g) transmitting both the encoded bitplanes and the encoded incorrectly predicted polarities of the table.

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Columbia City, IN, United States of America

Kenneth K Ellis