A method of determining the position of a user in 3D space is disclosed. In one example, the method comprises utilizing range measurements from one or more GPS satellite vehicles, angular information of a camera located at the user position, and a camera image associated with one or more known markers. The method further comprises determining the angular information of the camera by determining a direction cosine matrix between a camera frame of reference and an earth frame of reference, and designating unit vectors that individually extend from a position within the camera image associated with one of the known markers through the camera focal point to the respective known marker The method also includes integrating into an ordinary least squares matrix, the GPS range measurements, the angular information of the camera, and the unit vectors, and calculating the user position by solving the ordinary least squares matrix.