Tony K. Y. Chan

Interactive View-Dependent Rendering over Networks

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 parameter 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 in 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.

Syllable Alignment: A Novel Model for Phonetic String Search

Phonetic string search of written text is an important topic in Information Retrieval. While most of the previous methods convert a string into intermediate codes with phonetic transformation rules, this paper proposes a novel algorithm to segment two phonetic strings into syllables and find the optimal pairing of the corresponding syllables to calculate their similarity score. The experiment shows that this method is very effective and flexible. It can be easily adapted to different datasets and achieves optimal performance on average.

Using the Chinese Calligraphy brush as a tangible user interface tool in virtual heritage scenarios

This paper first presents a virtual heritage scenario and then discusses the implementation of using a Chinese Calligraphy brush as a tangible user interface tool to fit the context of this scenario. It then closely looks at how the brush has been implemented with basic and extended functionalities to the man-machine interface of the presented virtual environment.

A prototype of distributed molecular visualization on computational grids

This paper presents a distributed rendering system for visualization of massive molecular data sets on computational grids. It is designed with the ability to animate molecular dynamics (MD) simulation trajectories imported from a simulation engine in a distributed environment. MD simulation and visualization are computationally intensive tasks and computational grids are promising technologies for these applications. The framework of the system is introduced and the grid technologies and the parallel rendering approach are discussed in this paper.

Interacting with the virtually recreated Peranakans

Virtual Reality (VR) technology opens up many new possibilities. One of the new and upcoming areas this VR technology is rapidly being used for is in the Digital Heritage domain. With the abundant content and the need for preservation and conservation for cultural heritage, there has been an explosion of Digital Heritage projects worldwide. VR technology provides an important educational tool to recreate the cultural heritage content in an immersive high-quality 3D environment for the users to enter and experience the culture in real-time. Intuitive interaction techniques providing users other tools as an alternative to the conventional mouse and keyboard input also add to enhanced educational value. Here, we present a Digital Heritage project focusing on the Singapore region. We have selected the Peranakans and their Culture as the main topic for reconstruction using the VR technology. Innovative interaction techniques specific to the selected Digital Heritage content is also under development. This paper outlines the motivation, early developments, and implementation currently in progress.

View-dependent progressive mesh using non-redundant DAG hierarchy

We propose a non-redundant DAG hierarchy for view-dependent multiresolution mesh for client-server based online browsing of triangle mesh models. The multiresolution hierarchy and the selectively refined mesh for rendering are two relatively independent units, analogous to the server and the client. The multiresolution hierarchy, which is a DAG of vertex split operations, encodes all the dependent relationships between the vertex splits, so no extra legality checks on the surrounding neighborhood are required before a refinement or simplification operation. The DAG built by our algorithm has no redundant edges. This property can reduce run-time memory cost and time cost. We present a method to incrementally traverse the DAG as the viewing parameters change, and a mesh updating approach that is convenient for triangle budget control.

Optimized neighbour prefetch and cache for client-server based walkthrough

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.

Using virtual reality to bring Singaporean heritage to life

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.

Interactive view-dependent multiresolution on low-capacity clients

In this paper, we present a novel client-server scheme for view-dependent multiresolution rendering. The server hosts the multiresolution hierarchy, selects and delivers necessary mesh updates to the client according to the clients view parameters. The low-capacity client with limited triangle budget maintains the selectively refined mesh with little memory overhead and renders the mesh interactively to the end user. We focus on overcoming the network latency and realizing interactive frame rate on the client. Our solution is to make the client process and the server process run in parallel within a frame, and use the rendering time to cover the network latency. A view-parameters prediction mechanism is developed to make the parallelism of the client and the server feasible. Our approach dramatically reduces the frame time compared to the previous sequential method, and can achieve interactive frame rate in the system environment where the sequential method can not. The view-dependent rendering result of our parallel algorithm with predicted view parameters is very close to that of the sequential algorithm which uses actual view parameters. Also our prediction strategy and parallel algorithm can be extended to be used in networks with relatively long round-trip time.

Traversal on DAG-based Multiresolution Mesh Hierarchy

Traversal algorithm on the multiresolution hierarchy is critical for the view-dependent level of detail system. In this paper, we study multire solution hierarchy traversal for a DAG hierarchy of vertex-split/edge-collapse operations, in the context of a client-server based system. We present a general traversal management strategy that is beneficial for interactive frame rate and triangle-budget control, and is also favorable for the client-server based system. We adapt two commonly used traversal algorithms, linear traversal and priority-oriented traversal, to work under the management strategy. And we also propose a constant-time traversal algorithm. Extensive experiments on these three traversal algorithms are done and the comparison results can be used as a guide to choose the most appropriate traversal algorithm for different system requirements