Automated georegistration of motion imagery

Abstract

Georegistration is the assignment of 3-D coordinates to the pixels of an image. It is necessary for aligning imagery with map data, fusing images from different sensors, and geolocating moving objects. Georegistration requires recovery of the exterior camera orientation or pose—that is, position and attitude—for every image in the motion imagery sequence, and often the recovery of the intrinsic camera parameters of focal length, sensor pixel aspect ratio, and radial distortion. We have developed a real- time, automated solution to this problem. It is based on the registration of actual images to predicted images from a high-resolution digital elevation model (DEM). Beginning from an initial camera estimate for the first image, the algorithm iterates on the process of forming a predicted image, registering it to the actual image, and then refining the camera estimate based on the registration results. The resulting camera model forms the initial camera estimate of the next image. In this way, the camera model of each image is recovered as well as the platform motion, and the resulting camera models are used with the DEM to stabilize and georegister the motion imagery. The algorithm works with a wide variety of DEMs, including high-resolution LIDAR and low-resolution USGS DEMs. Implemented on a dual quad-core PC, the software georegisters one gigapixel of imagery per second. Results are presented for wide area motion imagery, full motion video, and thermal infrared video, along with applications to surveillance and border security.