External orientation of a mobile sensor via dynamic vision of digital map points

This paper describes an original method to determine the external orientation of a digital sensor located on a moving vehicle using exclusively the points of an already existing numerical cartography; the method is alternative to the one largely applied based on the use of satellite and inertial positioning systems. For solving the orientation parematers in a dynamic way a particular Kalman filter is applied, integrated of the so-called «wave algorithm» (Wang et al., 1995) belonging to the class of the «look ahead filters». The analytical model used considers the coplanarity equations, applied for the solution of dynamic vision problems (Soatto et al., 1996), the collinearity equations and a serie of state equations describing the motion of a moving vehicle by means of the application of spline functions to a set of points touched by the ruote and extracted from the digital mapping. In this way, it is possible to orient externally the images using exclusively photogrammetric observations and one odometer that measures the length of the course in function of time. Integrating the wave algorithm within the Kalman filter makes possible, in the space-time interval between two series of collinearity observations relative to cartographic points of known coordinates, to correct possible systematic deviations locally defined by the state equation model.