Stateless Remote Environment Navigation with View Compression

We present a set of very low bandwidth techniques for navigating remote environments. In a typical setup using our system, a virtual environment resides on a server machine, and one or more users explore the environment from client machines. Each client uses previous views of the environment to predict the next view, using the known camera motion and image-based rendering techniques. The server performs the same prediction, and sends only the difference between the predicted and actual view. Compressed difference images require significantly less bandwidth than the compressed images of each frame, and thus can yield much higher frame rates. To request a view, the client simply sends the coordinates of the desired view and of the previous view to the server. This avoids the overhead of maintaining connections between the server and each client. No restrictions are placed on the scene or the camera motions; the view compression technique may be used with arbitrarily complex 3D scenes or dynamically changing views from a web camera or a digital television broadcast. A lossy compression scheme is presented in which the client estimates the cumulative error in each frame, and requests a comprete refresh before errors become noticable. This work is applicable to remote exploration of virtual worlds such as on head-mounted displays, Digital Television, or over the Internet.