For a client-server based view-dependent rendering system, the overhead of view-dependent rendering and the network latency are major obstacles in achieving interactivity. In this paper, we first present a multiresolution hierarchy traversal management strategy to control the overhead of view-dependent rendering for low-capacity clients. Then we propose a predictive parallel strategy to overcome the network latency for client-server based view-dependent multiresolution rendering systems. Our solution is to make the client process and the server process run in parallel, using the rendering time to cover the network latency. For networks with long round-trip times, we manage to overlap the network latency for one frame with the rendering time for multiple frames. View-parameters prediction is incorporated to make the parallelism of the client and the server feasible. In order to maintain an acceptable view-dependent rendering quality in the network environment, we develop a synchronization mechanism and a dynamic adjustment mechanism to handle the transient network slowdowns and the changes of the network condition. Our experimental results, in comparison with the sequential method, show that our predictive parallel approach can achieve an interactive frame rate while keeping an acceptable rendering quality for large triangle models over networks with relatively long round-trip times.

Rapid advances in the field of virtual reality (VR) technology has opened up many new areas for research and development. One of the recent important research fields that has emerged is in the field of digital heritage. VR technology is an important educational tool that provides immersive and interactive qualities to the cultural heritage content thus enabling us to accurately represent digital reconstructions of heritage sites that are no longer in existence or are inaccessible. We present our project on the digital heritage scenario focusing on cultural heritage content specific to the Singapore region. Innovative interaction techniques specific to the selected digital heritage content will also be presented. We outline the motivation, early developments, and implementation currently in progress.

We present a position-based neighbour prefetch algorithm for client-server based walkthrough. This algorithm predicts which neighbouring viewcell will be needed in the near future according to the current view position of the client and prefetches the pre-computed potential visible set (PVS) for that viewcell to the client-side cache. Our algorithm has a low memory requirement for the client-side cache. With the same cache size, our algorithm offers a much better performance than the simple neighbour prefetch method. We also provide a delta-transmission algorithm to optimize the prefetch transmission procedure by avoiding transmitting those geometries that are already in the client-side cache. A cache management and entry replacement strategy is also proposed to maintain the client-side cache.

The representation of moving geometry entities is an important issue in the fields of CAD/CAM and robotic motion design. We present a method to interpolate the moving frame homogeneously using B-splines. By analysing the matrix representation of the moving frames, a simplified optimization functional is derived and a recursive iteration method is presented for approximating orthogonal frames at any position. The error caused by approximation and interpolation is given and is shown to be controllable. Since the calculation of moving frames is only related to linear equations of two or three unknowns, and the moving frames are approximated with a low-degree polynomial B-spline, the proposed approach can run very fast. The method is useful in motion design and the swept volume representation.