VIRTUAL REALITY AND ITS APPLICATIONS IN CHINA: AN OVERVIEW <s> VR, VISUALIZATION, AND IMAGING RESEARCH CENTRE AT THE CHINESE UNIVERSITY OF HONG KONG <s> A new data representation of image-based objects is presented. With this representation, the user can change the illumination as well as the viewpoint of an image-based scene. Physically correct imagery can be generated without knowing any geometrical information (e.g. depth or surface normal) of the scene. By treating each pixel on the image plane as a surface element, we can measure its apparent BRDF (bidirectional reflectance distribution function) by collecting information in the sampled images. These BRDFs allow us to calculate the correct pixel colour under a new illumination set-up by fitting the intensity, direction and number of the light sources. We demonstrate that the proposed representation allows re-rendering of the scene illuminated by different types of light sources. Moreover, two compression schemes, spherical harmonics and discrete cosine transform, are proposed to compress the huge amount of tabular BRDF data. © 1998 John Wiley & Sons, Ltd. <s> BIB001 </s> VIRTUAL REALITY AND ITS APPLICATIONS IN CHINA: AN OVERVIEW <s> VR, VISUALIZATION, AND IMAGING RESEARCH CENTRE AT THE CHINESE UNIVERSITY OF HONG KONG <s> An interactive virtual environment for simulation of bronchoscopy is developed. Medical doctor can safely plan their surgical bronchoscopy using the virtual environment without any invasive diagnosis which may risk the patient's health. The 3D pen input device of the system allows the doctor to navigate and visualize the bronchial tree of the patient naturally and interactively. To navigate the patient's bronchial tree, a vessel tracking process is required. While manual tracking is tedious and labor-intensive, fully automatic tracking may not be reliable. We propose a semi-automatic tracking technique called Intelligent Path Tracker which provides automation and enough user control during the vessel tracking. To support an interactive frame rate, we also introduce a new volume rendering acceleration technique, named as IsoRegion Leaping. The volume rendering is further accelerated by distributed rendering on a TCP/IP-based network of low-cost PCs. With these approaches, a 256 x 256 x 256 volume data of human lung, can be navigated and visualized at a frame rate of over 10 Hz in our virtual bronchoscopy system. <s> BIB002 </s> VIRTUAL REALITY AND ITS APPLICATIONS IN CHINA: AN OVERVIEW <s> VR, VISUALIZATION, AND IMAGING RESEARCH CENTRE AT THE CHINESE UNIVERSITY OF HONG KONG <s> Abstract For a long time, robot assembly programming has been produced in two environments: on-line and off-line. On-line robot programming uses the actual robot for the experiments performing a given task; off-line robot programming develops a robot program in either an autonomous system with a high-level task planner and simulation or a 2D graphical user interface linked to other system components. This paper presents a whole hand interface for more easily performing robotic assembly tasks in the virtual tenvironment. The interface is composed of both static hand shapes (states) and continuous hand motions (modes). Hand shapes are recognized as discrete states that trigger the control signals and commands, and hand motions are mapped to the movements of a selected instance in real-time assembly. Hand postures are also used for specifying the alignment constraints and axis mapping of the hand-part coordinates. The basic virtual-hand functions are constructed through the states and modes developing the robotic assembly program. The assembling motion of the object is guided by the user immersed in the environment to a path such that no collisions will occur. The fine motion in controlling the contact and ending position/orientation is handled automatically by the system using prior knowledge of the parts and assembly reasoning. One assembly programming case using this interface is described in detail in the paper. <s> BIB003
This is t he first government funded VR research center in Hong Kong, focusing on the development of practical virtual environments for medical and engineering applications. One pilot project of this center is to develop an intelligent virtual environment for computer simulation of bronchoscopy, a medical procedure used to diagnose and treat lung diseases BIB002 . The researchers at this center have worked on virtual hand interfaces using fuzzy logic and physics-based augmented hand interactions, as well as its applications in robotics simulation, engineering assembly, and virtual manufacturing BIB003 . Other work in the area of image-based VR is also conducted in order to facilitate interactive illumination and navigation control in an imagebased environment BIB001 . Fig. 6 is an image generated by the warping method. In addition, VR techniques have been used in architecture applications for the Department of Architecture (See Fig.  7 ).