US 6,192,322 B1Granted

Moving object and transient event detection using rotation strip aperture image measurements

AssigneeRaytheon Company

InventorsGerard L. Rafanelli, Susan B. Mount, Stephen K. Johnson, Marilyn A. Sperka, Eric B. Jensen, Mark J. Rehfield

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Abstract

A spinning strip aperture imaging radiometer sensor system and data processing methods for detecting moving objects derived from a plurality of image frames acquired by a strip aperture imaging sensor. A moving object in any individual image frame results in a motion smear signature in the total synthesized image. The motion smear signature is processed to detect the moving objects. One embodiment of the system comprises a rotating strip aperture telescope, a two dimensional detector array that detects images in the telescope's focal plane, a rotation compensation device that prevents rotational smear during integration time of detectors of the array, a signal processor that records a plurality of image frames of a scene imaged by the telescope as it rotates around its optical axis, and that implements method(s) for detecting the moving objects present in the recorded images. A hierarchy of moving object detection processors and methods 20 is disclosed that includes spatial, temporal, spatial frequency, and temporal frequency domain detection processors, and is compatible with multi-spectral background rejection techniques. Selection of the appropriate processing procedure and method depends upon the scenario, and the effective signal to noise ratio characteristics of the moving object.

Claims21

Dependent claims

A spinning strip aperture radiometer sensor system comprising:

a telescope having a focal plane and comprised of a rotating strip aperture that rotates around an optical axis and that produces temporally sequential images of a scene;
a two dimensional detector array for detecting images formed at the focal plane of the telescope;
a signal processor coupled to the two-dimensional detector array for recording a plurality of the temporally sequential images of the scene as the strip aperture rotates around the optical axis of the telescope, for synthesizing images from the plurality of temporally sequential images of the scene, and for simultaneously detecting moving objects found in the temporally sequential images of the scene;
wherein the signal processor additionally comprises:
means for correcting line of sight errors in at least two temporally sequential images of the scene to form spatially registered image frames;
means for spatially Fourier transforming the spatially registered image frames to a common spatial frequency to form spatially transformed frames;
means for filtering individual spatially transformed frames using a system transfer function equalization filter to form equalized frames;
means for differencing distinct pairs of equalized frames to form difference frames;
means for filtering the difference frames using a non-common passband rejection filter;
means for summing the filtered and difference frames to form a total summed spectrum of filtered differences;
means for inverse transforming the total summed spectra of filtered differences to provide a moving object signature in the spatial domain;
means for processing the moving object signature in the spatial domain through a matched filter array having a plurality of outputs;
and
means for comparing each of the plurality of outputs of the matched filter array to a corresponding predetermined threshold and declaring a moving object detection when at least one of the outputs of the matched filter array exceeds the corresponding predetermined threshold.

11 more elements

A spinning strip aperture radiometer sensor system comprising:

a telescope having a focal plane and comprised of a rotating strip aperture that rotates around an optical axis and that produces temporally sequential images of a scene;
a two dimensional detector array for detecting images formed at the focal plane of the telescope;
a signal processor coupled to the two-dimensional detector array for recording a plurality of the temporally sequential images of the scene as the strip aperture rotates around the optical axis of the telescope, for synthesizing images from the plurality of temporally sequential images of the scene, and for simultaneously detecting moving objects found in the temporally sequential images of the scene;
wherein the signal processor additionally comprises:
means for correcting line of sight errors in the plurality of temporally sequential images of the scene to form a plurality of spatially registered image frames;
means for spatially Fourier transforming the plurality of spatially registered image frames to a common spatial frequency grid to form spatially transformed frames;
means for filtering individual spatially transformed frames using a system transfer function equalization filter to form equalized frames;
means for differencing distinct pairs of equalized frames to form difference frames;
means for filtering the difference frames using a non-common passband rejection filter;
means for inverse transforming the filtered difference frames to provide a moving object signature in the spatial domain;
means for processing the moving object signature in the spatial domain through a matched filter array having a plurality of outputs;
and
means for comparing each of the plurality of outputs of the matched filter array to a corresponding predetermined threshold and declaring a moving object detection when at least one of the outputs of the matched filter array exceeds the corresponding predetermined threshold.

10 more elements

Dependencies are inferred from the claim text.