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CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
supported by the sibling associations ACADIA, CAADRIA, eCAADe, SIGraDi, ASCAAD and CAAD futures

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_id	4532
authors	Bono, Peter R.
year	1985
title	A Survey of Graphics Standards and Their Role in Information Interchange
source	IEEE Computer. October, 1985. vol. 18: pp. 63-75 : ill. ; tables. includes bibliography
summary	The survey describes each graphic standard and explains the interrelationships among the standards. The role and commercial impact of PCs serving as workstations in a distributed, network, multimedia environment is emphasized. It is shown that current graphics standardization activity focused on three principal areas: the application interface, the device interface, and picture exchange. The operator interface and hardware interfaces will be expected to be the subjects for standardization in the future. In addition, picture exchange will be replaced by information exchange, where information includes text, image, and voice components merged with graphics to create an integrated whole
keywords	computer graphics, standards, GKS, communication
series	CADline
last changed	2003/06/02 13:58

_id	8298
authors	Quadrel, Richard W. and Chassin, David P.
year	1985
title	Energy Graphics: A Progress Report on the Development of Architectural Courseware
source	ACADIA Workshop ‘85 [ACADIA Conference Proceedings] Tempe (Arizona / USA) 2-3 November 1985, pp. 129-141
doi	https://doi.org/10.52842/conf.acadia.1985.129
summary	Energy Graphics is a technique for determining the energy performance of buildings at the conceptual stage of the architectural design process. Unlike many energy analysis programs, which only produce results after ail of the building information has been supplied, Energy Graphics works with the designer in understanding how early decisions about building form and configuration affect energy use. The Energy Graphics technique is currently being "computerized" on a Sun 2/120 graphics workstation, under a grant by the Inter-University Consortium for Educational Computing. The resulting software will be used in the architectural design curriculum so that students will be able to receive an immediate energy evaluation of their design explorations. For use in the studios, the software must include a powerful graphics interface that allows students to "sketch" their design concepts interactively. The computer will then interpret these sketches as building information, organize them into an integrated database, perform the energy calculations, and inform the student of the results in a graphic format. One of the project's major goals is to provide this graphics interface in the same way that architects think about drawing, and not simply to imitate current computer "drafting" systems. The goals of the project can only be met by developing the software on a powerful workstation system, which provides fast processing time, large memory, multitasking capabilities and high-resolution graphics. This progress report describes our efforts to date on the development of this important software.
series	ACADIA
last changed	2022/06/07 08:00

_id	acadia06_068
id	acadia06_068
authors	Elys, John
year	2006
title	Digital Ornament
source	Synthetic Landscapes [Proceedings of the 25th Annual Conference of the Association for Computer-Aided Design in Architecture] pp. 68-78
doi	https://doi.org/10.52842/conf.acadia.2006.068
summary	Gaming software has a history of fostering development of economical and creative methods to deal with hardware limitations. Traditionally the visual representation of gaming software has been a poor offspring of high-end visualization. In a twist of irony, this paper proposes that game production software leads the way into a new era of physical digital ornament. The toolbox of the rendering engine evolved rapidly between 1974-1985 and it is still today, 20 years later the main component of all visualization programs. The development of the bump map is of particular interest; its evolution into a physical displacement map provides untold opportunities of the appropriation of the 2D image to a physical 3D object.To expose the creative potential of the displacement map, a wide scope of existing displacement usage has been identified: Top2maya is a scientific appropriation, Caruso St John Architects an architectural precedent and Tord Boonje’s use of 2D digital pattern provides us with an artistic production precedent. Current gaming technologies give us an indication of how the resolution of displacement is set to enter an unprecedented level of geometric detail. As modernity was inspired by the machine age, we should be led by current technological advancement and appropriate its usage. It is about a move away from the simplification of structure and form to one that deals with the real possibilities of expanding the dialogue of surface topology. Digital Ornament is a kinetic process rather than static, its intentions lie in returning the choice of bespoke materials back to the Architect, Designer and Artist.
series	ACADIA
email
last changed	2022/06/07 07:55

_id	8ae8
authors	Ayala, D., P. Brunet and Juan (et al)
year	1985
title	Object Representation by Means of Nominimal Division Quadtrees and Octrees
source	ACM Transactions on Graphics. January, 1985. vol. 4: pp. 41-59 : ill. includes bibliography
summary	Quadtree representation of two-dimensional objects is performed with a tree that describes the recursive subdivision of the more complex parts of a picture until the desired resolution is reached. At the end, all the leaves of the tree are square cells that lie completely inside or outside the object. There are two great disadvantages in the use of quadtrees as a representation scheme for objects in geometric modeling system: The amount of memory required for polygonal objects is too great, and it is difficult to recompute the boundary representation of the object after some Boolean operations have been performed. In the present paper a new class of quadtrees, in which nodes may contain zero or one edge, is introduced. By using these quadtrees, storage requirements are reduced and it is possible to obtain the exact backward conversion to boundary representation. Algorithms for the generation of the quadtree, boolean operation, and recomputation of the boundary representation are presented, and their complexities in time and space are discussed. Three- dimensional algorithms working on octrees are also presented. Their use in the geometric modeling of three-dimensional polyhedral objects is discussed
keywords	geometric modeling, algorithms, octree, quadtree, curves, curved surfaces, boolean operations
series	CADline
last changed	2003/06/02 13:58

_id	e191
authors	Fuchs, Henry, Goldfeather, Jack and Hultquist, Jeff P.
year	1985
title	Fast Spheres, Shadows, Textures, Transparencies, and Image Enhancements in Pixel-Planes
source	SIGGRAPH '85 Conference Proceedings. July, 1985. 1985. vol. 19 ; no. 3: pp. 111-120 : ill. includes bibliography
summary	Pixel-planes is a logic-enhanced memory system for raster graphics and imaging. Although each pixel-memory is enhanced with a one-bit ALU, the system's real power comes from a tree of one-bit address that can evaluate linear expressions Ax + By + C for every pixel (x,y) simultaneously, as fast as the ALUs and the memory circuits can accept the results. The development of a variety of algorithms that exploit this fast linear expression evaluation capability has started. The paper reports some of those results. Illustrated in this paper is a sample image from a small working prototype of the Pixel- planes hardware and a variety of images from simulations of a full-scale system. Timing estimates indicate that 30,000 smooth shaded triangles can be generated per second, or 21, 000 smooth-shaded and shadowed triangles can be generated per second, or over 25,000 shaded spheres can be generated per second. Image-enhancement by adaptive histogram equalization can be performed within 4 seconds on a 512 x 512 image
keywords	shadowing, image processing, algorithms, polygons, clipping, computer graphics, technology, hardware
series	CADline
last changed	2003/06/02 10:24

_id	ae09
authors	Lieberman, Henry
year	1985
title	There's More to Menu Systems Than Meets the Screen
source	SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 181-189 : ill. includes bibliography
summary	Love playing with those fancy menu-based graphical user interfaces, but afraid to program one yourself for your own application? Do windows seem opaque to you? Are you scared of Mice? Like what-you-see-is-what-you-get but don't know how to get-what-you-want-to-see on the screen? Everyone agrees using systems like graphical document illustrators, circuit designers, and iconic file systems is fun, but programming user interfaces for these systems isn't as much fun as it should be. Systems like the Lisp Machines, Xerox D- Machines, and Apple Macintosh provide powerful graphics primitives, but the casual applications designer is often stymied by the difficulty of mastering the details of window specification, multiple processes, interpreting mouse input, etc. This paper presents a kit called EZWin, which provides many services common to implementing a wide variety of interfaces, described as generalized editors for sets of graphical objects. An individual application is programmed simply by creating objects to represent the interface itself, each kind of graphical object, and each command. A unique interaction style is established which is insensitive to whether commands are chosen before or after their arguments. The system anticipates the types of arguments needed by commands preventing selection mistakes which are a common source of frustrating errors. Displayed objects are made 'mouse-sensitive' only if selection of the object is appropriate in the current context. The implementation of a graphical interface for a computer network simulation is described to illustrate how EZWin works
keywords	user interface, computer graphics
series	CADline
last changed	1999/02/12 15:09

_id	2ae0
authors	Bairstow, Jeffrey N.
year	1985
title	Chip Design Made Easy
source	high Technology. June, 1985. pp. 18-25 : ill. includes bibliography: p. 74
summary	The combination of powerful engineering workstations and novel software tools is making custom chip design economical even for engineers without the specific training. The availability of new automated design technology is promoted by the changing market dynamics. The design of an integrated circuit, with hardware choices, is described
keywords	business, AI, electrical engineering, hardware
series	CADline
last changed	2003/06/02 13:58

_id	ascaad2006_paper20
id	ascaad2006_paper20
authors	Chougui, Ali
year	2006
title	The Digital Design Process: reflections on architectural design positions on complexity and CAAD
source	Computing in Architecture / Re-Thinking the Discourse: The Second International Conference of the Arab Society for Computer Aided Architectural Design (ASCAAD 2006), 25-27 April 2006, Sharjah, United Arab Emirates
summary	These instructions are intended to guide contributors to the Second Architecture is presently engaged in an impatient search for solutions to critical questions about the nature and the identity of the discipline, and digital technology is a key agent for prevailing innovations in architectural design. The problem of complexity underlies all design problems. With the advent of CAD however, Architect’s ability to truly represent complexity has increased considerably. Another source that provides information about dealing with complexity is architectural theory. As Rowe (1987) states, architectural theory constitutes “a corpus of principles that are agreed upon and therefore worthy of emulation”. Architectural theory often is a mixed reflection on the nature of architectural design, design processes, made in descriptive and prescriptive terms (see Kruft 1985). Complexity is obviously not a new issue in architectural theory. Since it is an inherent characteristic of design problems, it has been dealt with in many different ways throughout history. Contemporary architects incorporate the computer in their design process. They produce architecture that is generated by the use of particle systems, simulation software, animation software, but also the more standard modelling tools. The architects reflect on the impact of the computer in their theories, and display changes in style by using information modelling techniques that have become versatile enough to encompass the complexity of information in the architectural design process. In this way, architectural style and theory can provide directions to further develop CAD. Most notable is the acceptance of complexity as a given fact, not as a phenomenon to oppose in systems of organization, but as a structuring principle to begin with. No matter what information modelling paradigm is used, complex and huge amounts of information need to be processed by designers. A key aspect in the combination of CAD, complexity, and architectural design is the role of the design representation. The way the design is presented and perceived during the design process is instrumental to understanding the design task. More architects are trying to reformulate this working of the representation. The intention of this paper is to present and discuss the current state of the art in architectural design positions on complexity and CAAD, and to reflect in particular on the role of digital design representations in this discussion. We also try to investigate how complexity can be dealt with, by looking at architects, in particular their styles and theories. The way architects use digital media and graphic representations can be informative how units of information can be formed and used in the design process. A case study is a concrete architect’s design processes such as Peter Eisenman Rem Koolhaas, van Berkel, Lynn, and Franke gehry, who embrace complexity and make it a focus point in their design, Rather than viewing it as problematic issue, by using computer as an indispensable instrument in their approaches.
series	ASCAAD
email
last changed	2007/04/08 19:47

_id	e234
authors	Kalay, Yehuda E. and Harfmann, Anton C.
year	1985
title	An Integrative Approach to Computer-Aided Design Education in Architecture
source	February, 1985. [17] p. : [8] p. of ill
summary	With the advent of CAD, schools of architecture are now obliged to prepare their graduates for using the emerging new design tools and methods in architectural practices of the future. In addition to this educational obligation, schools of architecture (possibly in partnership with practicing firms) are also the most appropriate agents for pursuing research in CAD that will lead to the development of better CAD software for use by the profession as a whole. To meet these two rather different obligations, two kinds of CAD education curricula are required: one which prepares tool- users, and another that prepares tool-builders. The first educates students about the use of CAD tools for the design of buildings, whereas the second educates them about the design of CAD tools themselves. The School of Architecture and Planning in SUNY at Buffalo has recognized these two obligations, and in Fall 1982 began to meet them by planning and implementing an integrated CAD environment. This environment now consists of 3 components: a tool-building sequence of courses, an advanced research program, and a general tool-users architectural curriculum. Students in the tool-building course sequence learn the principles of CAD and may, upon graduation, become researchers and the managers of CAD systems in practicing offices. While in school they form a pool of research assistants who may be employed in the research component of the CAD environment, thereby facilitating the design and development of advanced CAD tools. The research component, through its various projects, develops and provides state of the art tools to be used by practitioners as well as by students in the school, in such courses as architectural studio, environmental controls, performance programming, and basic design courses. Students in these courses who use the tools developed by the research group constitute the tool-users component of the CAD environment. While they are being educated in the methods they will be using throughout their professional careers, they also act as a 'real-world' laboratory for testing the software and thereby provide feedback to the research component. The School of Architecture and Planning in SUNY at Buffalo has been the first school to incorporate such a comprehensive CAD environment in its curriculum, thereby successfully fulfilling its obligation to train students in the innovative methods of design that will be used in architectural practices of the future, and at the same time making a significant contribution to the profession of architecture as a whole. This paper describes the methodology and illustrates the history of the CAD environment's implementation in the School
keywords	CAD, architecture, education
series	CADline
email
last changed	2003/06/02 13:58

_id	0e5e
authors	Kociolek, A.
year	1986
title	CAD in Polish Building
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 235-245
summary	There is little CAAD in Polish architectural design offices, and only recently have practising architects discovered the computer. On the other hand, CAAD has been used for some time in research and development based at universities or in large design organizations. This chapter gives a broad picture of the computerization of building design in Poland, a complex process which concerns planning and financing, hardware, software, CAD practice, standardization, training, education, etc. Here architectural applications are treated on an equal basis, together with other applications representing design disciplines involved in design, such as structural and mechanical engineering. The underlying philosophy of this chapter is a belief that proper and well-balanced computerization of design in building which leaves creative work to human beings should result in better design and eventually in improvements in the built environment. Therefore integration of the design process in building seems more important for design practice than attempts to replace an architect by a computer, although the intellectual attraction of this problem is recognized.
series	CAAD Futures
last changed	1999/04/03 17:58

_id	244d
authors	Monedero, J., Casaus, A. and Coll, J.
year	1992
title	From Barcelona. Chronicle and Provisional Evaluation of a New Course on Architectural Solid Modelling by Computerized Means
source	CAAD Instruction: The New Teaching of an Architect? [eCAADe Conference Proceedings] Barcelona (Spain) 12-14 November 1992, pp. 351-362
doi	https://doi.org/10.52842/conf.ecaade.1992.351
summary	The first step made at the ETSAB in the computer field goes back to 1965, when professors Margarit and Buxade acquired an IBM computer, an electromechanical machine which used perforated cards and which was used to produce an innovative method of structural calculation. This method was incorporated in the academic courses and, at that time, this repeated question "should students learn programming?" was readily answered: the exercises required some knowledge of Fortran and every student needed this knowledge to do the exercises. This method, well known in Europe at that time, also provided a service for professional practice and marked the beginning of what is now the CC (Centro de Calculo) of our school. In 1980 the School bought a PDP1134, a computer which had 256 Kb of RAM, two disks of 5 Mb and one of lO Mb, and a multiplexor of 8 lines. Some time later the general politics of the UPC changed their course and this was related to the purchase of a VAX which is still the base of the CC and carries most of the administrative burden of the school. 1985 has probably been the first year in which we can talk of a general policy of the school directed towards computers. A report has been made that year, which includes an inquest adressed to the six Departments of the School (Graphic Expression, Projects, Structures, Construction, Composition and Urbanism) and that contains interesting data. According to the report, there were four departments which used computers in their current courses, while the two others (Projects and Composition) did not use them at all. The main user was the Department of Structures while the incidence of the remaining three was rather sporadic. The kind of problems detected in this report are very typical: lack of resources for hardware and software and for maintenance of the few computers that the school had at that moment; a demand (posed by the students) greatly exceeding the supply (computers and teachers). The main problem appeared to be the lack of computer graphic devices and proper software.
series	eCAADe
email
last changed	2022/06/07 07:58

_id	20a8
authors	Ruffle, Simon
year	1986
title	How Can CAD Provide for the Changing Role of the Architect?
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 197-199
summary	At the RIBA Conference of 1981 entitled 'New Opportunities', and more recently at the 1984 ACA Annual Conference on 'Architects in Competition' there has been talk of marketing, new areas of practice, recapturing areas of practice lost to other professions, more accountability to client and public 'the decline of the mystique of the professional'. It is these issues, rather than technical advances in software and hardware, that will be the prime movers in getting computers into widespread practice in the future. In this chapter we will examine how changing attitudes in the profession might affect three practical issues in computing with which the author has been preoccupied in the past year. We will conclude by considering how, in future, early design stage computing may need to be linked to architectural theory, and, as this is a conference where we are encouraged to be outspoken, we will raise the issue of a computer-based theory of architecture.
series	CAAD Futures
email
last changed	2003/05/16 20:58

_id	22eb
authors	Schley, Michael
year	1985
title	CAD Buyer's Checklist
source	Architectural Technology. Summer, 1985. pp. 50-55 : ill
summary	Selecting a computer-aided design system is difficult. Computers confront architects with a bewildering array of capabilities and prices. The performance checklist here can be a big help in evaluating CAD systems. By grading different systems using the same criteria, it is easier to separate fact from impression. Also, it is a useful way to reveal deficiencies that a typical demonstration might hide
keywords	business, CAD, systems, practice, management, hardware, software, architecture
series	CADline
last changed	1999/02/12 15:09

_id	e235
authors	Van Norman, Mark
year	1985
title	THE USER INTERFACE IN PROGRAMS FOR DESIGN EDUCATION: ISSUES AND CRITERIA
source	ACADIA Workshop ‘85 [ACADIA Conference Proceedings] Tempe (Arizona / USA) 2-3 November 1985, pp. 155-168
doi	https://doi.org/10.52842/conf.acadia.1985.155
summary	Due to inexpensive mass-marketed microcomputers and CAAD software the type of "clients" we serve as CAAD educators will soon change. In addition to teaching CAAD programming to 20 students a semester, we may soon be serving a much larger group of casual users from design studios and technical courses. These casual users will require that we provide programs and hardware which allow them to design a better product more swiftly and with less effort than by hand. The most crucial factor in meeting these criteria is the quality of the user interface of the programs and equipment we provide. At Harvard, we have studied the user interfaces of more than 80 programs used in 10 areas of design. This paper is a summary of a 90 page report in which issues are raised, the answers to which determine the quality of the user interface of a program. In the summarized report, different approaches to resolving each issue are discussed, but no "answers" are provided. In our roles as authors, teachers, and now, consumers of CAAD programs, we must - explicitly or by default - address these issues before designing or purchasing programs and hardware for design education.
series	ACADIA
type	normal paper
last changed	2022/06/07 07:58

_id	02c6
authors	Wheeler, B.J.Q
year	1986
title	A Unified Model for Building
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 200-231
summary	It is commonly recognized that the time-honoured procedure for preparing an architectural design for building on site is inefficient. Each member of a team of consultant professionals makes an independently documented contribution. For a typical project involving an architect and structural, electrical, mechanical and public services engineers there will be at least five separate sets of general- arrangement drawings, each forming a model of the building, primarily illustrating one discipline but often having to include elements of others in order to make the drawing readable. For example, an air-conditioning duct-work layout is more easily understood when superimposed on the room layout it serves which the engineer is not responsible for but has to understand. Both during their parallel evolution and later, when changes have to be made during the detailed design and production drawing stages, it is difficult and time consuming to keep all versions coordinated. Complete coordination is rarely achieved in time, and conflicts between one discipline and another have to be rectified when encountered on site with resulting contractual implications. Add the interior designer, the landscape architect and other specialized consultants at one end of the list and contractors' shop drawings relating to the work of all the consultants at the other, and the number of different versions of the same thing grows, escalating the concomitant task of coordination. The potential for disputes over what is the current status of the design is enormous, first, amongst the consultants and second, between the consultants and the contractor. When amendments are made by one party, delay and confusion tend to follow during the period it takes the other parties to update their versions to include them. The idea of solving this problem by using a common computer-based model which all members of the project team can directly contribute to is surely a universally assumed goal amongst all those involved in computer-aided building production. The architect produces a root drawing or model, the 'Architect's base plan', to which the other consultants have read-only access and on top of which they can add their own write-protected files. Every time they access the model to write in the outcome of their work on the project they see the current version of the 'Architect's base plan' and can thus respond immediately to recent changes and avoid wasting time on redundant work. The architect meanwhile adds uniquely architectural material in his own overlaid files and maintains the root model as everybody's work requires. The traditional working pattern is maintained while all the participants have the ability to see their colleagues, work but only make changes to those parts for which they are responsible.
series	CAAD Futures
last changed	1999/04/03 17:58

_id	ce52
authors	Abram, Greg, Weslover, Lee and Whitted, Turner
year	1985
title	Efficient Alias-Free Rendering using Bit-masks and Look-up Tables
source	SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 53-59 : ill. (some col.). includes bibliography
summary	The authors demonstrate methods of rendering alias-free synthetic images using a precomputed convolution integral. The method is based on the observation that a visible polygon fragment's contribution to an image is solely a function of its position and shape, and that within a reasonable level of accuracy, a limited number of shapes represent the majority of cases encountered in images commonly rendered. The basic technique has been applied to several different rendering algorithms. A version of the newly non-uniform sampling technique implemented in the same program but with different tables values was introduced
keywords	algorithms, computer graphics, anti-aliasing
series	CADline
last changed	2003/06/02 13:58

_id	678e
authors	Aish, Robert
year	1986
title	Three-dimensional Input and Visualization
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 68-84
summary	The aim of this chapter is to investigate techniques by which man-computer interaction could be improved, specifically in the context of architectural applications of CAD. In this application the object being designed is often an assembly of defined components. Even if the building is not actually fabricated from such components, it is usually conceptualized in these terms. In a conventional graphics- based CAD system these components are usually represented by graphical icons which are displayed on the graphics screen and arranged by the user. The system described here consists of three- dimensional modelling elements which the user physically assembles to form his design. Unlike conventional architectural models which are static (i.e. cannot be changed by the users) and passive (i.e. cannot be read by a CAD system), this model is both 'user generated' and 'machine readable'. The user can create, edit and view the model by simple, natural modelling activities and without the need to learn complex operating commands often associated with CAD systems. In particular, the user can view the model, altering his viewpoint and focus of attention in a completely natural way. Conventional computer graphics within an associated CAD system are used to represent the detailed geometry which the different three-dimensional icons may represent. In addition, computer graphics are also used to present the output of the performance attributes of the objects being modelled. In the architectural application described in this chapter an energy- balance evaluation is displayed for a building designed using the modelling device. While this system is not intended to offer a completely free-form input facility it can be considered to be a specialist man-machine interface of particular relevance to architects or engineers.
series	CAAD Futures
email
last changed	2003/11/21 15:15

_id	8a90
authors	Buchmann, Alejandro P. and Gerzso, Miguel J.
year	1985
title	Handling Heterogeneously Formatted Data in an Object Oriented Database Environment
source	NCGA - National Computer Graphics Association Conference Proceedings. 1985. vol. 3: pp. 645-655 : ill. includes bibliography
summary	The paper discussed the problems associated with handling heterogeneously formatted data and the interfacing of the subsystems of a CAD system that intervene in the handling of these data: the database management system, the graphic display system and application programs. Object-oriented languages with message passing capabilities were offered as a feasible solution which was illustrated through examples in the language TM
keywords	CAD, systems, languages, computer graphics, database
series	CADline
last changed	2003/06/02 10:24

_id	c341
authors	Cohen, Michael F. and Greenberg, Donald P.
year	1985
title	The Hemi-Cube: A Radiosity Solution for Complex Environments
source	SIGGRAPH '85 conference proceedings. July, 1985. vol. 19 ; no. 3: pp. 31-39 : ill. (some col.). includes bibliography
summary	This paper presents a comprehensive method to calculate object to object diffuse reflections within complex environments containing hidden surfaces and shadows. In essence, each object in the environment is treated as a secondary light source. The method provides an accurate representation of the 'diffuse' and 'ambient' terms found in typical image synthesis algorithms. The phenomena of 'color bleeding' from one surface to another, shading within shadow envelopes, and penumbras along shadow boundaries are accurately reproduced. Additional advantages result because computations are independent of viewer position. This allows the efficient rendering of multiple views of the same scene for dynamic sequences. Light sources can be modulated and object reflectivities can be changed, with minimal extra computation. The procedures extend the radiosity method beyond the bounds previously imposed
keywords	hidden surfaces, shadowing, computer graphics, geometric modeling, radiosity
series	CADline
last changed	2003/06/02 13:58

_id	23bc
authors	Demko, Stephen, Hodges, Laurie and Naylor, Bruce F.
year	1985
title	Construction of Fractal Objects with Iterated Function Systems
source	SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 271-278 : ill. col. includes bibliography
summary	In computer graphics, geometric modeling of complex objects is a difficult process. An important class of complex objects arise from natural phenomena: trees, plants, clouds, mountains, etc. Researchers are investigating a variety of techniques for extending modeling capabilities to include these as well as other classes. One mathematical concept that appears to have significant potential for this is fractals. Much interest currently exists in the general scientific community in using fractals as a model of complex natural phenomena. However, only a few methods for generating fractal sets are known. We have been involved in the development of a new approach to computing fractals. Any set of linear maps (affine transformations) and an associated set of probabilities determines an Iterated Function System (IFS). Each IFS has a unique 'attractor' which is typically a fractal set (object). Specification of only a few maps can produce very complicated objects. Design of fractal objects is made relatively simple and intuitive by the discovery of an important mathematical property relating the fractal sets to the IFS. The method also provides the possibility of solving the inverse problem, given the geometry of an object, determine an IFS that will (approximately) generate that geometry. This paper presents the application of the theory of IFS to geometric modeling
keywords	computer graphics, geometric modeling, fractals, visualization
series	CADline
last changed	2003/06/02 13:58

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