1. Electro-optical system for determining position and orientation of a mobile part, said system comprising a fixed part comprising projection means and having a center of projection and the mobile part, the fixed part being linked rigidly with a virtual image plane, the mobile part being linked rigidly with at least a first linear electro-optical device and a second linear electro-optical device, the projection means projecting into a zone comprising the electro-optical devices, at least two networks of beams, whose intersection with the image plane defines at least two networks of nonparallel straight lines, each of the networks of straight lines comprising at least three parallel segments, each of the first and second electro-optical devices being intercepted by the networks of beams at at least two triples of points, wherein the two electro-optical devices being coplanar and their direction secant, the orientation and the position of the mobile part is determined using a first vanishing point E and a second vanishing point F, in the image plane, respectively of a first straight line comprising the first linear electro-optical device and of a second straight line comprising the second linear electro-optical device, calculation means determining, on the basis of the points of intersections of the networks of beams on the first and second linear electro-optical devices, positions of: a. projections on the image plane of a first triple (A, I, B) of points whose positions are known in a benchmark frame linked with the first linear electro-optical device; b. projections on the image plane of a second triple of points (C, J, G) whose positions are known in a benchmark frame linked with the second linear electro-optical device; and, c. the first vanishing point E and of the second vanishing point F.