Abstract. This paper describes research that investigated the application of the Global Positioning System (GPS) and 3DOF angular tracking to address the registration problem in visualization of construction graphics in outdoor Augmented Reality (AR) environments. AR is the overlaying of virtual images and computer-generated information over scenes of the real world so that the user’s resulting view is enhanced or augmented beyond the normal experience. One of the basic issues in AR is the registration problem. Objects in the real world and superimposed virtual objects must be properly aligned with respect to each other, or the illusion that the two coexist in augmented space is compromised. In the presented research, the global position and the 3D orientation of the user’s viewpoint (i.e. longitude, latitude, altitude, heading, pitch, and roll) are tracked, and this information is reconciled with the known global position and orientation of superimposed CAD objects. The result is an augmented outdoor environment where superimposed CAD objects stay fixed to their real world locations as the user moves freely on a construction site. The algorithms are implemented in a prototype platform called UM-AR-GPS-ROVER that is capable of interactively placing 3D CAD models at any desired location in an outdoor augmented space.