Collaborative sighting

Abstract

Collaborative sighting is performed using plural optical sighting apparatuses that each comprise: a camera unit and a display device. Geometric calibration of the camera units with respect to the imaged scene is performed by detecting features within captured images, generating descriptors from respective patches of the image at the features; detecting corresponding descriptors from different images, Position and deriving the geometric calibration from the positions in the respective images of the corresponding descriptors. A target location in the image captured by a first optical sighting apparatus is designated and a corresponding location relative to the image captured by the second one optical sighting apparatus is identified from the geometric calibration. The display device of the second optical sighting apparatus indicates where the corresponding location lies relative to the displayed image.

What is claimed is: 
     
         1 . A method of collaborative sighting using plural optical sighting apparatuses that each comprise: a camera unit arranged to capture an image of a portion of a scene within the field of view of the camera unit; and a display device arranged to display the image captured by the camera unit, the method comprising:
 detecting features within images captured by the camera units of the optical sighting apparatuses;   generating descriptors in respect of each image from respective patches of the image at the position of each detected feature;   detecting corresponding descriptors generated from different images;   deriving the geometric calibration of the camera units with respect to the scene from the positions in the respective images of the features corresponding to the detected corresponding descriptors;   in respect of at least one target location in the image captured by the camera unit of a first one of the optical sighting apparatuses, identifying, from the derived geometric calibration of the camera units, a corresponding location relative to the image captured by the camera unit of a second one of the optical sighting apparatuses that corresponds to a target location in the scene that itself corresponds to the target location in the image captured by the camera unit of the first one of the optical sighting apparatuses; and   indicating on the display device of the second optical sighting apparatus where the corresponding location lies relative to the displayed image.