An articulated tractor for towing an aircraft comprising a front section including an engine means and a rear section pivoted to the front section, the rear section defining a nose wheel clamp means for engaging and raising the nose wheel of an aircraft. The invention is characterized in that said method comprises a first step of generating a projected disparity map from an original disparity map, and a second step of filling holes within said projected disparity map, the first step comprising the sub-step of removing isolated projected pixels on said projected disparity map by filtering them. The photoacid generators are compatible with resins and can control acid diffusion and are thus suited for use in chemically amplified resist compositions.