Abstract: A system for determining the attitude of an airborne or spaceborne platform such as a terrain image sensor or an energy beam pointer 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 platform or 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 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.

Abstract: 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.