1. A method of determining the absolute position of at least one target object point in a scene, the method 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 method comprising: analysing the images to identify sets of image points in plural images of the series of images corresponding to common object points in the scene; and performing a bundle adjustment on the identified sets of image points that estimates parameters representing the positions of the object points relative to the positions of the camera on capture of the respective images taking into account the absolute positions of the camera represented by the position data as a prior without deriving modified estimates of the positions of the camera, and without using input orientation data measured by a sensor associated with the camera representing the orientation of the camera on capture of the images to set initial estimates of the orientations of the camera on capture of the respective images, and deriving the absolute position of the target object point on the basis of the results of the bundle adjustment referenced by the absolute positions of the camera on capture of the respective images represented by the position data.