Abstract: The absolute position of a target object point is determined using a series of images of the scene with overlapping fields of view captured by a camera in positions arranged in at least two dimensions across the scene and position data representing the absolute positions of the camera on capture of the respective images. The images are analyzed to identify sets of image points corresponding to common object points in the scene. A bundle adjustment is performed on the sets of image points that estimates parameters representing the positions of the object points relative to the positions of the camera associated with each image, but without using input orientation data representing the orientation of the camera. The absolute position of the target object point is derived on the basis of the results of the bundle adjustment and the absolute positions of the camera represented by the position data.

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.