Patent Document ID: 10147201
Application ID: 15563516
Patent Status: 1

Claim One:
1. A method of determining the absolute geographic direction of an object of a scene, with a desired performance in azimuth and elevation of the 0.1 to milli-radian class, comprising a learning phase and an online operation phase, the learning phase comprising the following steps: acquisition by circular scanning by a channel of a first optronic imaging device in the visible, near infrared, short infrared, medium infrared or far infrared domain, of determined fixed position, of a series of partially overlapping optronic images, including an image or several images of the scene (step A 1 ), automatic extraction from the images, of descriptors defined by their image coordinates and their radiometric characteristics, with at least one descriptor of unknown direction in each overlap of images (step B 1 ), from the descriptors extracted from the overlaps between images, automatic estimation of the mutual relative rotation of the images and mapping of the descriptors extracted from the overlaps (step C 1 ), identification in the images, of at least one known reference geographic direction of precision compatible with the desired performance, and determination of the image coordinates of each reference (step D 1 ), from the descriptors extracted from the overlaps and mapped, the direction and image coordinates of each reference, automatic estimation of the attitude of each image and estimation of the focal length of the first imaging device with precision compatible with the desired performance, being a fine registration step (step E 1 ), from the attitude of each image, the position and internal parameters of the first imaging device including the focal length, and the image coordinates of each descriptor, computation of the absolute directions of the descriptors according to a predetermined model of image capture of the imaging device (step F 1 ), the online operation phase comprising the following steps: acquisition of at least one image of the object called current image, from a second imaging device in the same fixed position as the first imaging device (step A 2 ), automatic extraction of descriptors from each current image (step B 2 ), automatic mapping of the descriptors of each current image with the descriptors whose absolute direction was calculated in the learning phase, to determine the absolute direction of the descriptors of each current image (step C 2 ), from the absolute directions of the descriptors of each current image, automatic estimation of the attitude of each current image (step D 2 ), from the image coordinates of the object in each current image, the attitude of each current image, the position and internal parameters of the second imaging device, automatic computation of the absolute direction of the object according to a model of image capture of each current image (step E 2 ).