Functionally Based Virtual Computer Art

This article describes how virtual embossing and wood cutting can be done using the function representation of a shape and tools. The software is implemented as an interactive shape modeler where a functional model of the shape is subsequently modified with offset and set-theoretic operations. For visualization, interactive ray tracing is used. Bounding boxes together with the spatial organization of the functional model provide the required fast function evaluation that is usually a bottleneck for functionally based shape modeling systems. The software runs on a personal computer. Categories and Subject Descriptors I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling - Curve, surface, solid, and object representations; I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism -- Raytracing, Virtual reality; I.3.8 [Computer Graphics]: Applications. Keywords Computer art, embossing, carving, virtual reality, functionally based shape modeling.

From a Small Formula to Cyberworlds

Abstract. Cyberworlds created on the web allow for providing personal mentoring of the students with different cultural and educational backgrounds. Virtual Campus of Nanyang Technological University is designed to be such a cyberworld. This is a place for research and education, fun and immersion in campus life. Besides standard VRML, its hybrid function-based extension is used in the design of Virtual Campus. In place of thousands of polygons, small formulas are used for constituting complex geometric shapes and appearances. Collaborative Shape Modeling Laboratory, which is a part of the Virtual Campus, is based on this extension. It is developed to help students with their computer graphics assignments. 1 Online Experiences Versus Online Courses Cyber-learning has already become an important and vital part of university education. Conventional ways of teaching, when only lectures and practical exercises in a class are used, no longer satisfy the growing demands and challenges of modern education. This becomes especially essential when large or distributed classes are bein

Image-driven virtual simulation of arthroscopy

In recent years, minimally invasive arthroscopic surgery has replaced a number of conventional open orthopedic surgery procedures on joints. While this achieves a number of advantages for the patient, the surgeons have to learn very different skills, since the surgery is performed with special miniature pencil-like tools and cameras inserted through little incisions while observing the surgical field on video monitor. Therefore, virtual reality simulation becomes an alternative to traditional surgical training based on hundreds years old apprentice–master model that involves either real patients or increasingly difficult to procure cadavers. Normally, 3D simulation of the virtual surgical field requires significant efforts from the software developers but yet remains not always photorealistic. In contrast to this, for photorealistic visualization and haptic interaction with the surgical field we propose to use real arthroscopic images augmented with 3D object models. The proposed technique allows for feeling the joint cavity displayed on video monitor as real 3D objects rather than their images while various surgical procedures, such as menisectomy, are simulated in real time. In the preprocessing stage of the proposed approach, the arthroscopic images are stitched into panoramas and augmented with implicitly defined object models representing deformable menisci. In the simulation loop, depth information from the mixed scene is used for haptic rendering. The scene depth map and visual display are reevaluated only when the scene is modified

Interactive visualization of mathematics in 3D web

We propose a new educational web-enabled 3D shape modeling framework that does not restrict to a list of predefined primitive geometric objects and allows the user to interactively create objects by incremental modifications of the basic shape with the tool shapes that are defined by analytical functions. The shape definition is eventually a function script which can be rendered on any suitable graphics system. The function script includes accelerating structures that significantly improve the shape rendering performance allowing us to sustain interactivity with large number of interactive operations applied

Interactive cutting of thin deformable objects

Simulation of cutting is essential for many applications such as virtual surgical training. Most existing methods use the same triangle mesh for both visualization and collision handling, although the requirements for them in the interactive simulation are different. We introduce visual-collision binding between high-resolution visual meshes and low-resolution collision meshes, and thus extend the spatially reduced framework to support cutting. There are two phases in our framework: pre-processing and simulation. In the pre-processing phase, the fvisual-collision binding is built based on the computation of geodesic paths. In the simulation phase, the cutting paths are detected on the collision triangles and then mapped to local 2D coordinates systems in which the intersections between visual mesh and the cutting paths are calculated. Both collision and visual meshes are then re-meshed locally. The visual-collision binding is updated after cutting, based on which the collision-simulation and visual-simulation embedding are updated locally. Experimental results show that our cutting method is an efficient and flexible tool for interactive cutting simulation.MOE (Min. of Education, S’pore)Published versio