Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 42


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 41
41 GLOSSARY 4-D Technology--computerized animated 3-D model that preserves scenic, aesthetic, historic, and environmental portrays movement through space, over a period of time. resources, while maintaining safety and mobility. CSD is An example would be virtual reality-based computer an approach that considers the total context within which graphics. a transportation improvement project will exist. Cathode ray tube (CRT)--display device used in most com- Context-sensitive solutions (CSS)--philosophy wherein safe puter displays, video monitors, televisions, and oscillo- transportation solutions are designed in harmony with the scopes. The CRT developed from Philo Farnsworth's community. CSS strives to balance environmental, scenic, work was used in all television sets until the late 20th cen- aesthetic, cultural, and natural resources, as well as com- tury and the advent of plasma screens, LCDs (liquid crys- munity and transportation service needs. tal displays), and other technologies. Designbuild (DB)--project delivery method in which the Compact Disc Read-Only Memory (CD-ROM)--version of agency or owner holds a single contract with a single the compact disc that allows information to be stored and entity for both the design and construction of a project. retrieved. Once a CD-ROM is pressed, new data cannot be Designbuild is owner-driven, and it commonly reduces stored and the disc cannot be erased for reuse. Although project delivery time by eliminating lengthy bidding CD-ROMs look like music discs, they can only be used proceedings. with a computer equipped with a CD-ROM drive. Digital terrain model (DTM)--topographic model of the Computer-aided design (CAD)--use of computer programs bare earth that can be manipulated by computer programs. and systems to design detailed 2-D or 3-D models of The data files contain the elevation data of the terrain in a physical objects, such as mechanical parts, buildings, and digital format that relates to a rectangular grid. Vegetation, molecules. buildings, and other cultural features are removed digi- Computer-aided drafting and design, computer-aided design tally, leaving just the underlying terrain. and drafting, or computer-aided design development Environmental impact statement (EIS)--document that stud- (CADD)--use of the computer to help with the drafting of ies all likely impacts that will result from major trans- product plans. portation projects. Impacts include those on the natural Computer-aided engineering (CAE)--use of computers to environment, as well as those on the economy and society, help with all phases of engineering design work. Similar and those on the built environment of historical and aes- to computer-aided design, it also involves the conceptual thetic significance. and analytical design steps. FHWA--federal agency that administers federal highway Computer-aided manufacturing (CAM)--process of using programs. The agency reviews all Transportation Plans specialized computers to control, monitor, and adjust tools and Transportation Improvement Programs to ensure com- and machinery in manufacturing. pliance with federal planning and funding requirements. Computer animation--art of creating moving images by Geographic information systems (GIS)--system of hardware means of computers. It is a subfield of computer graphics and software used for storage, retrieval, mapping, and and animation. Increasingly it is created by means of 3-D analysis of geographic data. GIS differs from CADD and computer graphics, although 2-D computer graphics are other graphical computer applications in that all spatial still widely used. Sometimes the target of the animation is data are geographically referenced to a map projection in the computer itself; sometimes the target is another an earth coordinate system. For the most part, spatial data medium, such as film. can be "re-projected" from one coordinate system into Computer-generated imagery (CGI)--application of the field another; therefore, data from various sources can be of computer graphics (or more specifically 3-D computer brought together into a common database and integrated graphics) to special effects. CGI is used in movies, televi- using GIS software. sion programs and commercials, and in printed media. Global Positioning System (GPS)--worldwide radio naviga- Real-time computer graphics, such as those in video tion system formed from a constellation of 24 satellites games, are rarely referred to as CGI. and their ground stations. GPS uses these "man-made Computer numerical control (CNC)--technology that has stars" as reference points to calculate positions accurate to been around since the early 1970s. Before this, it was called a matter of meters. NC, for numerical control. A CNC equivalent system can Information technology (IT)--technology required for infor- be programmed to duplicate the repetitive and mundane mation processing. In particular, the use of computers and manual labor manufacturing operations in a much more computer software to convert, store, protect, process, automatic, accurate, and cost-efficient fashion. transmit, and retrieve information from anywhere at Context-sensitive design (CSD)--collaborative, interdisci- anytime. plinary approach that involves all stakeholders to develop ISO 9000--family of standards and guidelines for quality in a transportation facility that fits its physical setting and the manufacturing and service industries from the Interna-

OCR for page 41
42 tional Organization for Standardization (ISO). ISO 9000 Raster graphics--data file or structure representing a generally defines the criteria for what should be measured. ISO 9001 rectangular grid of pixels, or points of color, on a computer covers design and development; ISO 9002 covers produc- monitor, paper, or other display device. The color of each tion, installation, and service; and ISO 9003 covers final pixel is individually defined; images in the redgreenblue testing and inspection. ISO 9000 certification does not (RGB) color space, for instance, often consist of colored guarantee product quality. It ensures that the processes pixels defined by three bytes--one byte each for red, green, that develop the product are documented and perform in a and blue. Less colorful images require less information per quality manner. pixel; an image with only black and white pixels requires Metropolitan planning organization (MPO)--regional orga- only a single bit for each pixel. Raster graphics are distin- nization responsible for comprehensive transportation guished from vector graphics in that vector graphics repre- planning and programming in urbanized areas. Work sent an image through the use of geometric objects such as products include the Transportation Plan, the Transporta- curves and polygons. tion Improvement Program, and the Unified Planning Render farm--computer cluster to render computer gener- Work Program. ated imagery, typically for film and television special Multimedia development--systems that support the interac- effects. The rendering of images is a highly parallelizable tive use of text, audio, still images, video, and graphics. activity, as each frame can be calculated independently of Each of these elements must be converted in some way the others, with the main communication between proces- from analog form to digital form before they can be used sors being the upload of the initial models and textures, in a computer application. Thus, the distinction of multi- and the download of the finished images. media is the convergence of previously diverse systems. Rendering--the process of generating an image from a Network distributed rendering--process of aggregating the description of 3-D objects, by means of a software pro- power of several computing entities to collaboratively run gram. The description is in a strictly defined language or a single computational task in a transparent and coherent data structure and would contain geometry, viewpoint, way, so that they appear as a single, centralized system. texture, and lighting information. The image is a digital Occupational Safety and Health Administration (OSHA)-- image/raster graphics image. branch of the U.S. Department of Labor responsible for Return on investment (ROI)--calculation used to determine establishing and enforcing safety and health standards in whether a proposed investment is wise and how well it will the workplace. repay the investor. It is calculated as the ratio of the Personal computers (PCs)--home or office desktop com- amount gained (taken as positive), or lost (taken as nega- puter systems that run Microsoft DOS and Windows oper- tive), relative to the basis. ating systems. Texture mapping--process of assigning a material to an object Pixel--one of the many tiny dots that makes up the repre- similar to the specification provided to the building contrac- sentation of a picture in a computer's memory. Usually the tor. To duplicate the object's surface quality, it is necessary dots are so small and so numerous that, when printed on to obtain this information in a digital format. One way to cre- paper or displayed on a computer monitor, they appear to ate a texture map is by scanning a physical sample material merge into a smooth image. The color and intensity of provided by the designer or to scan a photograph. each dot is chosen individually by the computer to repre- Value engineering (VE)--federal, state, and local highway sent a small area of the picture. agencies are responsible for getting the best overall proj- Polygon--closed planar path composed of a finite number of ect value for the taxpayer. Applying the VE process to sequential line segments. The straight line segments that suitable projects will help one achieve this purpose. Sim- make up the polygon are called its sides or edges and the ply stated, VE is an organized application of common points where the sides meet are the polygon's vertices. If sense and technical knowledge directed at finding and a polygon is simple, then its sides (and vertices) constitute eliminating unnecessary costs in a project. the boundary of a polygonal region, and the term polygon Vector graphics or geometric modeling--use of geometrical sometimes also describes the interior of the polygonal primitives such as points, lines, curves, and polygons to rep- region (the open area that this path encloses) or the union resent images in computer graphics. It is used by contrast to of both the region and its boundary. the term raster graphics, which is the representation of Project managers--person responsible for the planning, images as a collection of pixels (dots). coordination, and controlling of a project from inception Virtual reality--artificial environment created with computer to completion, meeting the project's requirements and hardware and software and presented to the user in such a ensuring completion on time, within cost, and to required way that it appears and feels like a real environment. To quality standards. Often, there is a project manager and a "enter" a virtual reality, a user dons special gloves, ear- consultant project manager. phones, and goggles, all of which receive their input from Random access memory (RAM)--type of computer storage the computer system. In this way, at least three of the five whose contents can be accessed in any order. Computers use senses are controlled by the computer. In addition to feed- RAM to hold the program code and data during execution. ing sensory input to the user, the devices also monitor the

OCR for page 41
43 user's actions. The goggles, for example, track how the eyes struction. This technology has been pioneered by the U.S. move and respond accordingly by sending new video input. military for flight and combat simulation and is rapidly Virtual reality simulation--real-time simulation is a graphical becoming a key tool for the Urban Design and Planning database technology that allows for interactive navigation community. Although traditional visualization methods throughout a digital model. The database can foster rapid have been used as a presentation tool, real-time simulation conceptual approvals, identify design flaws, and, ultimately, streamlines the complex phases of a planning and designing reduce development costs before commencement of con- a project.