The purpose of this study is to model the beam/decking connectors (nails) of a glulam dome cap by beam/connector elements, and to analyze various dome cap models in order to investigate the potential of the beam/connector model to simulate the decking. Two- and three-dimensional beam/connector elements are formulated, tested, and evaluated. The dome cap is modeled with I-DEAS, and the modeling procedures are briefly discussed. Four series of beam/connector dome cap models are created and analyzed: (1) models with the nailed joints at bracing points (rigid link h=0), (2) models with the nailed joints at bracing points (h>0), (3) models with 16 nailed joints per beam element (h=0), and (4) models with 16 nailed joints per beam element (h>0). Their results are compared with the dome cap models with the truss bracings. Finally, conclusions and recommendations for future research are presented. / Master of Science

Volume rendering, the direct display of data from 3D scalar fields, is an area of computer graphics still in its infancy. Only recently has graphics hardware advanced to a state where volume rendering became feasible. Volume rendering requires the analysis of large amounts of data, typically tens of megabytes. As hardware speeds increase, we can only expect the datasets to get larger. This thesis describes a reasonably fast, space efficient algorithm for volume rendering. The algorithm is device independent since it is written as an X Windows client. It makes no graphics calls to dedicated graphics hardware, but allows the X server to take advantage of such hardware when it exists. It can be run on any machine that supports X Windows, from an IBM-PC to a high-end graphics workstation. It produces a perspective projection of the volume, since perspective projections are generally easier to interpret than parallel projections. The algorithm uses progressive refinement to give the user a quick view of the dataset and how it is oriented. If a different orientation or dataset is desired, the user may interrupt the rendering process. Once the desired dataset and position have been determined, the progressive refinement process continues and the image improves in quality until the greatest level of detail is displayed. While this algorithm may not be as fast as algorithms written specifically for dedicated graphics hardware, its overall rendering time is acceptable. Hardware vendors who develop X servers that take advantage of their graphics capabilities will only enhance the performance of our algorithm. The device independence this algorithm provides is a major benefit for people who work in an environment of mixed hardware platforms. / Master of Science

The project focuses on computer tools suitable for particular game genres and how they are used to develop 3D computer games. As part of learning about the tools, the author developed a 3D computer adventure game called "Adventures of Smiley" using Macromedia Director MX and 3D Studio Max. The game's purpose is to engage children using a friendly interface while they learn about different topics in various subject areas through lessons and puzzles. The research gathered information about the current game industry, technologies and game genres, which can be used as a reference for the beginning level game programmer. The project documentation and the game are also published on the Internet and can be freely accessed online.

This project included the development of a multi-user game that takes place in a 3 dimensional world of the computer science department. Basically, the game allows prospective students to meet existing students and faculty in a virtual open house that takes place within the third floor of Jack Brown Hall. Users can walk around Jack Brown Hall and type text messages to chat with each other.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / Structure from Motion suggests that an object or scene’s three-dimensional structure can be determined from its observed two-dimensional motion. Human efforts, manifested in computer algorithms, try to mimic the enormous power of the visual processing capabilities of the human brain. We present an algorithm to estimate structure, using the Unscented Kalman Filter, from the motion of point-wise features, produced by the Kanade-Lucas-Tomasi feature tracker. The algorithm is evaluated critically against an extensive set of motion sequences, with special attention paid to facial feature reconstruction.

A two-dimensional structural analysis design approach has been the universally accepted method for a small structural engineering design firm. The tools to perform the analysis have been paper and pencil, calculators and more recently personal computers with two-dimensional software. With the introduction of three-dimensional software, a major shift is occurring on how small structural engineering firms approach analysis and design. This thesis research reviews the analysis of an existing building utilizing the standard two-dimensional approach, including horizontal diaphragm-action within wood floors. This study also reviews the research performed on horizontal diaphragms and investigates the use of three-dimensional, finite element modeling (RISA-3D) for the analysis of horizontal diaphragms. It is shown that the three-dimensional model can provide results similar to the two-dimensional hand calculations. However, the thickness of the diaphragm elements has to be significantly modified for flexible diaphragm action. The experience described herein is useful for structural engineer interfacing within three-dimensional CAD systems. The thesis concludes with a discussion on the challenges facing small structural engineering firms, including computer based technologies, engineering expertise to develop contract documents and review shop drawings, and outsourcing of design services.

Various Image Based Rendering (IBR) techniques have been proposed to reconstruct scenes from its images. Voxel-based IBR algorithms reconstruct Lambertian scenes well, but fail for specular objects due to limitations of their consistency checks. We show that the conventional consistency techniques fail due to the large variation in reflected color of the surface for different viewing positions. We present a new consistency approach that can predict this variation in color and reconstruct specular objects present in the scene. We also present an evaluation of our technique by comparing it with three other consistency methods.

Three-dimensional scans and other volumetric data sources often result in representations that are more complex topologically than the original model. The extraneous critical points, handles, and components are called topological noise. Many algorithms in computer graphics require simple topology in order to work optimally, including texture mapping, surface parameterization, flows on surfaces, and conformal mappings. The topological noise disrupts these procedures by requiring each small handle to be dealt with individually. Furthermore, topological descriptions of volumetric data are useful for visualization and data queries. One such description is the contour tree (or Reeb graph), which depicts when the isosurfaces split and merge as the isovalue changes. In the presence of topological noise, the contour tree can be too large to be useful. For these reasons, an important goal in computer graphics is simplification of the topology of volumetric data. The key to this thesis is that the global topology of volumetric data sets is determined by local changes at individual points. Therefore, we march through the data one grid cell at a time, and for each cell, we use a local check to determine if the topology of an isosurface is changing. If so, we change the value of the cell so that the topology change is prevented. In this thesis we describe variations on the local topology check for use in different settings. We use the topology simplification procedure to extract a single component with controlled topology from an isosurface in volume data sets and partially-defined volume data sets. We also use it to remove critical points from three-dimensional volumes, as well as time-varying volumes. We have applied the technique to two-dimensional (plus time) data sets and three dimensional (plus time) data sets.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Don Brutzman, Curtis Blais. Includes bibliographical references (p. 103-104). Also available online.

Current trends indicate that the population explosion and invasion of information technology, particularly in developing nations, are likely to overwhelm education systems and policy makers, educators, researchers and therefore the community faces enormous challenges. Also, many graduates of various levels and disciplines appear unable to practically apply their knowledge in problem solving situations. In an attempt to achieve and maintain high educational standards, many nations are devoting substantial proportions of the gross domestic product toward educational endeavours. However, few systems are adopting modern education practices that intrinsically motivate and engage learners, and are at the same time flexible enough to consider students' aspirations and interests. It is argued that such systems would make learning more relevant, meaningful and enjoyable to the learners and are bound to improve exit performances. In such a system, the role of the teacher is that of a facilitator, and not instructor. Constructivism, a philosophy which holds that knowledge is actively constructed by learners through learning, is regarded as promising to provide a long-term solution to many educational problems since its underlying principles are argued to be holistic. It has become imperative that technology in general and the computer in particular should play a role as educational tools as these have capabilities that could be designed to make learning relevant and interesting to learners. It is argued that its use within constructivist approaches and curriculum considerations would increase learner abilities. An eclectic approach to curriculum design is advised for success in this endeavour. Since computers permeate most aspects of our lives (directly or indirectly) their inclusion in teaching and learning situations must become a reality. This project is focused on underscoring the fact that computer based education (CBE), under constructivist philosophy, can provide solutions to problems brought about by extreme interpretations of the deductive or traditional teaching approach. Particularly, it attempts to show that use of three-dimensional (3D) visualizations could significantly aid comprehension and perception of, among other units of discourse, cytoplasmic structure, geo-referenced graphical data, and the understanding of spatial relationships. This is a technique that has, in the recent past, received little attention and no extensive educational research has been carried out with the aim of perfecting it. Recent research carried out by members of the Biological Pedagogy (Bioped) research group identified conceptual problems in learners regarding biological processes such as photosynthesis and respiration. Having established that the misconceptions in learners were attributable to their lack of visualization ability, the first part of the project involved identifying some of the specific visual problems. A qualitative research approach was used to ascertain from university lecturers what convictions, beliefs and experiences they had had with their students that related to use of visualization skills. Skills most required included interpretation of 2D and 3D structures as well as their rotation in space. A survey was also carried out among Cell Biology first and second year students of the School of Life and Environmental Studies in order to precisely determine aspects of three-dimensionality and visual skills suspected to cause conceptual difficulties. Quantitative data analysis showed that the most deficient skills in the learners included pattern folding (projecting 2D material into 3D objects), orientation of form (identifying 3D objects that are oriented differently) and rotation (identifying 3D objects from top and front views). These findings corroborated qualitative analysis of lecturers opinions and convictions. An educational computer game was designed with the aim of ameliorating these problems. The game consisted of 3D scenes where puzzles related to the skills mentioned above needed to be solved. It was recommended that visualization skills should be incorporated into the biology curriculum for all undergraduate students within the first year of the course. / Thesis (M.Ed.)-University of Natal, 1999.