Modeling and Interacting with Architectural-Scale Scenes





AbstractA major problem challenging opera designers is the inability to co- ordinate lighting, projection systems, and set designs in the prelim- inary planning phase. New computer graphics techniques, which provide the set and lighting designer [be opportunity to evaluate, test, and control opera designs prior to the construction of full scale systems are presented, These techniques—light source input. simu- lation of directional lighting, modeling of scenic projection systems, and full three-dimensional simulation—show the potential for the use of computer graphics in theater design,

The light source input component consists of a program for as- signing light source attributes with a set of theater lighting icons. This module allows a designer to specify light source characteristics in a way familiar to the discipline and to make preliminary evalua- tions of the lighting conditions.

An extended progressive radiosity method is introduced to sim- ulate the directional lighting characteristics which are specified by the input program.

A new projection approach is presented to simulate the optical effects of scenic projectors. In addition, a solution to the distortion problem produced by angular projections is described.

The above components are integrated to produce full three- dimensional simulations of the global illumination effects in an opera scene. 



Abstract: We present a new approach to lighting design for image synthesis. It is based on the inverse problem of determining light settings for an environment from a description of the desired solution. The method is useful for determining light intensities to achieve a desired effect in a computer simulation and can be used in conjunction with any rendering algorithm. Given a set of lights with fixed positions, we determine the light intensities and colors that most closely match the target image painted by the designer using a constrained least squares approach. We describe an interactive system that allows flexible input and display of the solution.



Abstract During the three decades since Ivan Sutherland introduced the Sketchpad system, there has been an outpouring of computer graphics systems for use in architecture. In response to this development, most of the major architectural firms around the world have embraced the idea that computer literacy is mandatory for success. We would argue, however, that most of these recent developments have failed to tap the potential of the computer as a design tool. Instead, computers have been relegated largely to the status of drafting instruments, so that the "D" in CAD stands for drafting rather than design. It is important that future architectural design systems consider design as a continuous process rather than an eventual outcome.The advent of computer graphics technology has had an impact on the architectural profession. Computer graphics has revolutionized the drafting process, enabling the rapid entry and modification of designs. In addition, modeling and rendering systems have proven to be invaluable aids in the visualization process, allowing designers to walk through their designs with photorealistic imagery. Computer graphics systems have also demonstrated utility for capturing engineering information, greatly simplifying the analysis and construction of proposed designs. However, it is important to consider that all of these tasks occur near the conclusion of a larger design process. In fact, most of the artistic and intellectual challenges of an architectural design have already been resolved by the time the designer sits down in front of a computer. In seeking insight into the design process, it is generally of little use to revisit the various computer archives and backups. Instead, it is best to explore the reams of sketches and crude balsa models that fill the trash cans of any architectural studio.In architecture, as in most other fields, the initial success of computerization has been in areas where it frees humans from tedious and mundane tasks. This includes the redrawing of floor plans after minor modifications, the generation of largely redundant, yet subtly different engineering drawings and the generation of perspective renderings.We believe that there is a largely untapped potential for computer graphics as a tool in the earlier phases of the design process. In this essay, we argue that computer graphics might play a larger role via applications that aid and amplify the creative process.

Journal Article: Computer Graphics and Applications, IEEE, vol. 20, no. 3 (2000)
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We present a new inverse, interactive approach to acoustic design that applies optimization techniques to an acoustic simulation system. The work builds on previous work in computer graphics dealing with the analogous problem in lighting design. The user interactively indicates a range of acceptable material and geometric modifications for an auditorium or similar space and specifies acoustic goals by choosing target values for a set of acoustic measures. Given this set of goals and constraints, the system performs an optimization of surface material and geometric parameters using a combination of simulated annealing and steepest descent techniques. Visualization tools extract and present the simulated sound field data for points sampled in space and time. The user then manipulates the visualizations to create an intuitive expression of acoustic design goals. We demonstrate an interactive system and report results for two performance spaces.



Abstract  Three-dimensional (3D) image acquisition systems are rapidly becoming more affordable, especially systems based on commodity electronic cameras. At the same time, personal computers with graphics hardware capable of displaying complex 3D models are also becoming inexpensive enough to be available to a large population. As a result, there is potentially an opportunity to consider new virtual reality applications as diverse as cultural heritage and retail sales that will allow people to view realistic 3D objects on home computers.Although there are many physical techniques for acquiring 3D data—including laser scanners, structured light and time-of-flight—there is a basic pipeline of operations for taking the acquired data and producing a usable numerical model. We look at the fundamental problems of range image registration, line-of-sight errors, mesh integration, surface detail and color, and texture mapping. In the area of registration we consider both the problems of finding an initial global alignment using manual and automatic means, and refining this alignment with variations of the Iterative Closest Point methods. To account for scanner line-of-sight errors we compare several averaging approaches. In the area of mesh integration, that is finding a single mesh joining the data from all scans, we compare various methods for computing interpolating and approximating surfaces. We then look at various ways in which surface properties such as color (more properly, spectral reflectance) can be extracted from acquired imagery. Finally, we examine techniques for producing a final model representation that can be efficiently rendered using graphics hardware.



Abstract  In this article, we propose a hybrid approach to solving the inverse problem of reconstructing a foliaged tree. Our method involves first constructing the skeleton(trunk and the major branches) of the tree, and then applying an L-system starting from this skeleton. L-systems are one of the better-known procedural models in the graphics community, especially after their popularization by Lindenmayer and Prusinkiewicz. The “Related Work” sidebar provides some background on L-systems.



Abstract  This paper describes the successful combination of pre-generated and dynamically updated image-based representations to accelerate the visualization of complex virtual environments. We introduce a new type of impostor, which has the desirable property of limiting de-occlusion errors to a user-specified amount. This impostor, composed of multiple layers of textured meshes, replaces the distant geometry and is much faster to draw. It captures the relevant depth complexity in the model without resorting to a complete sampling of the scene. We show that layers can be dynamically updated during visualization. This guarantees bounded scene complexity in each frame and also exploits temporal coherence to improve image quality when possible. We demonstrate the strengths of this approach in the context of city walkthroughs.