Patent ID: 6084989
Filing Date: 2000-07-04
Classification: G06T

Abstract:
A method of determining offset errors between line and pixel coordinates of landmarks in a digitized image generated by a passive imaging system disposed on a spacecraft and line and pixel coordinates predicted by a mathematical model of the imaging system, said method comprising the steps of:defining and storing a plurality of landmarks in a landmark database that are each defined as having a perimeter comprising a plurality of boundary vertices;generating a digitized image of a softcopy map derived from a database that is viewed on a display;selecting a landmark in the softcopy map for processing;reading out the plurality of boundary vertices of the landmark stored in the landmark database that corresponds to the selected landmark in the softcopy map;processing the plurality of boundary vertices of the stored landmark using a mathematical model of the passive imaging system to generate absolute coordinates of boundary pixels of the stored landmark;upsampling and rasterizing the absolute coordinates of boundary pixels of the stored landmark to generate a landmark mask;processing the digitized image derived from the passive imaging system to extract an image patch containing the selected landmark;upsampling the image patch so that it has the same magnification as the upsampled landmark mask; andprocessing the upsampled image patch and the upsampled landmark mask by an image matching algorithm to determine offset errors between the respective images.