초록 ▼

A system for determining the attitude of an airborne platform such as a terrain image sensor includes a digital image correlator for comparing successive overlapping, instantaneous images of the terrain which are recorded by a second, two-dimensional image sensor whose image plane is oriented parall

A system for determining the attitude of an airborne platform such as a terrain image sensor includes a digital image correlator for comparing successive overlapping, instantaneous images of the terrain which are recorded by a second, two-dimensional image sensor whose image plane is oriented parallel to that of the terrain image sensor. The second sensor generates an instantaneous master image and a subsequent slave image which at least partially overlaps the master image in terms of the terrain which is viewed. The master and slave images are approximately registered and a correlation is performed. A plurality of points on the slave image are correlated with the corresponding terrain points on the master image. The correlation is performed by selecting a plurality of spatially distributed patches of pixel arrays which are mathematically superimposed on and are moved about the slave image to determine the locations where the maximum of gray scale correlation occurs. These correlation points on the slave image are recorded and the coplanarity condition of photogrammetry determines the relative orientation of the slave with respect to the master. The relative orientation of the slave image with respect to the master image characterizes the attitude change of the platform. The technique also reveals changes in altitude and velocity of the platform when mean altitude and velocity are known. The image produced by the terrain image sensor can be altered on a real time basis using the information relating to the changes in platform attitude, or the master and slave image data can be recorded for subsequent use in modifying the image data recorded by the terrain image sensor.

대표청구항 ▼

A method of determining changes in the yaw, pitch, roll or elevation of an airborne sensor which moves along a flight path above the earth and records successive two-dimensional images of the earth\s surface along said flight path, comprising the steps of: (A) generating a first set of data represen

A method of determining changes in the yaw, pitch, roll or elevation of an airborne sensor which moves along a flight path above the earth and records successive two-dimensional images of the earth\s surface along said flight path, comprising the steps of: (A) generating a first set of data representing picture elements of a first two-dimensional image of said surface at a first point along said flight path such that the data representing all of the picture elements of said first image are generated simultaneously; (B) generated a second set of data representing picture elements of a second two-dimensional image of said surface at a second point along said flight path closely spaced from said first point such that at least a portion of said images overlap each other, and wherein the data representing all of the picture elements of said second image are generated simultaneously, said picture elements varying in intensity in accordance with their respective locations on the corresponding images, the corresponding picture elements of the first and second images in the overlapping portions thereof being offset from each other by an amount related to changes in the yaw, pitch, roll or elevation of said sensor; (C) correlating a plurality of corresponding picture elements of the first and second images in the overlapping portions thereof, the relative positions of the correlated picture elements representing the changes in the yaw, pitch, roll or elevation of said sensor, and wherein the step of correlating is performed at least in part by selecting at least three spaced apart N×M arrays of picture elements in one of said images, selecting at least three spaced apart reference picture elements in the other of said images which are respectively associated with said at least three N×M arrays, and comparing the at least three reference picture elements with the picture elements in the associated N×M arrays.