When calculating an angle of articulation between two portions of an articulated vehicle such as a tractor-trailer combination, a camera-based articulation angle measuring system comprises camera(s) mounted on the tractor and/or trailer that observe their counterpart and/or features on the other portion of the vehicle. The angles or locations of the counterpart features are measured in the image(s) produced by the camera(s). A geometric model is employed to convert the location and/or angular measurements into a corresponding articulation and/or roll angle for the tractor-trailer combination.