DIGITAL AERIAL IMAGE MOSAIC METHOD AND APPARATUS

A computer-implemented method and system for use in alignment of multiple digital images to form a mosaic image involves selecting multiple search site points (SSPs) in an overlapping area of a pair of the digital images and searching for an interesting point (IP) near each of the SSPs. The system involves the calculation of a numeric interest measure (IM) at each of multiple IP-candidate sites near the SSPs. The IM is indicative of the presence of image features at the IP-candidate site and provides a basis for comparing the IP-candidate sites at each of the SSPs and selecting the IP-candidate site having the most significant IM. In a preferred embodiment, IP-candidate sites having an IM that does not exceed a predetermined minimum threshold are discarded. The method also involves locating a tie point (TP) on an overlapping one of the digital images correlating to the IP. The TP together with the IP comprise a tie point pair (TPP) that can be used to calculate and apply geometric transformations to align the images and thereby form a seamless mosaic. The system and method may also involve radiometric balancing of the images to reduce tonal mismatch.