We introduce on active object tracking algorithm that maintains relative calibration between a camera projector pair for augmented-relaity applications. The approach is motivated by the growing use of digital light projectors for human computer interaction and novel display environments. These domains typically require known relative calibration between the camera and projector so that events detected ib the camera (i.e. a user pushbutton selection) can correctly impact the projected display. The tracking algorithm detects both real world landmarks and projected fiducials and updates the transform that will bring them into alignment in each frame. The active pursuit tracker is demonstrated in the context of an application that allows users to visualize a virtual volume of three-dimensional data simply by physically positioning a display plane within the space.