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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Hits 1 to 20 of 68

_id caadria2007_677
id caadria2007_677
authors Anbusivan, R.
year 2007
title Automation of Passive Solar Design System
source CAADRIA 2007 [Proceedings of the 12th International Conference on Computer Aided Architectural Design Research in Asia] Nanjing (China) 19-21 April 2007
summary This research, focus on the automation of passive solar design system using computational method. The quantitative nature of passive solar design system makes the automation possible. The automation is done in stages, because implementing the passive solar design system is not an isolated process, but intertwined with the overall design process. The first phase of automation concentrates in conceptual stage, to avoid major deviations in later stages of the design. The conceptual stage use Eco-grammar (A preset Design guidelines for corresponding climate) and user inputs for initial form generation. The second stage of automation is done after the user finalize the model with respect to its position rotation and arrangements. In this stage manipulation of vertex, edges and faces of the forms were manipulated using genetic algorithm. The value of mutation or crossover done in genetic algorithm is suggested by knowledge engine (preloaded design knowledge). Until the form obtains or reach closer to the desired values of performance the loop between analysis and mutation, crossover will be continued. On the basis of analysis result further manipulations may change from the previous which is guided by the knowledge engine.
series CAADRIA
email anbusivanr@gmail.com
last changed 2008/06/16 08:48

_id cc15
authors Ansaldi, Silvia, De Floriani, Leila and Falcidieno, Bianca
year 1985
title Geometric Modeling of Solid Objects by Using a Face Adjacency Graph Representation
source SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 131-139 : ill. includes bibliography
summary A relational graph structure based on a boundary representation of solid objects is described. In this structure, called Face Adjacency Graph, nodes represent object faces, whereas edges and vertices are encoded into arcs and hyperarcs. Based on the face adjacency graph, the authors define a set of primitive face-oriented Euler operators, and a set of macro operators for face manipulation, which allow a compact definition and an efficient updating of solid objects. The authors briefly describe a hierarchical graph structure based on the face adjacency graph, which provides a representation of an object at different levels of detail. Thus it is consistent with the stepwise refinement process through which the object description is produced
keywords geometric modeling, graphs, objects, representation, data structures,B-rep, solid modeling, Euler operators
series CADline
last changed 2003/06/02 08:24

_id bcf7
authors Arvin, Scott A. and House, Donald H.
year 2002
title Modeling architectural design objectives in physically based space planning
source Automation in Construction 11 (2) (2002) pp. 213-225
summary Physically based space planning is a means for automating the conceptual design process by applying the physics of motion to space plan elements. This methodology provides for a responsive design process, which allows a designer to easily make decisions whose consequences immediately propagate throughout the design. It combines the speed of automated design methods with the flexibility of manual design methods, while adding a highly interactive quality and a sense of collaboration with the design itself. In our approach, the designer creates a space plan by specifying and modifying graphic design objectives rather than by directly manipulating primitive geometry. The plan adapts to the changing state of objectives by applying the physics of motion to its elements. For design objectives to affect a physically based space plan, they need to apply appropriate forces to space plan elements. Space planning can be separated into two problems, determining topological properties and determining geometric properties. Design objectives can then be categorized as topological or geometric objectives. Topological objectives influence the location of individual spaces, affecting how one space relates to another. Geometric objectives influence the size and shape of space boundaries, affecting the dimensions of individual walls. This paper focuses on how to model a variety of design objectives for use in a physically based space planning system. We describe how topological objectives, such as adjacency and orientation can be modeled to apply forces to space locations, and how geometric objectives, such as area, proportion, and alignment, can be modeled to apply forces to boundary edges.
series journal paper
email arvin@viz.tamu.edu
more http://www.elsevier.com/locate/autcon
last changed 2003/05/15 19:22

_id f317
authors Arvin, Scott A. and House, Donald H.
year 1999
title Modeling Architectural Design Objectives in Physically Based Space Planning
source Media and Design Process [ACADIA ‘99 / ISBN 1-880250-08-X] Salt Lake City 29-31 October 1999, pp. 212-225
summary Physically based space planning is a means for automating the conceptual design process by applying the physics of motion to space plan elements. This methodology provides for a responsive design process, which allows a designer to easily make decisions whose consequences immediately propagate throughout the design. It combines the speed of automated design methods with the flexibility of manual design methods, while adding a highly interactive quality and a sense of collaboration with the design itself. In our approach, the designer creates a space plan by specifying and modifying graphic design objectives rather than by directly manipulating primitive geometry. The plan adapts to the changing state of objectives by applying the physics of motion to its elements. For design objectives to have an effect on a physically based space plan, they need to be able to apply appropriate forces to space plan elements. Space planning can be separated into two problems, determining topological properties and determining geometric properties. Design objectives can then be categorized as topological or geometric objectives. Topological objectives influence the location of individual spaces, affecting how one space relates to another. Geometric objectives influence the size and shape of space boundaries, affecting the dimensions of individual walls. This paper focuses on how to model a variety of design objectives for use in a physically based space planning system. We describe how topological objectives, such as adjacency and orientation, can be modeled to apply forces to space locations, and how geometric objectives, such as area, proportion, and alignment, can be modeled to apply forces to boundary edges.
series ACADIA
email arvin@viz.tamu.edu
last changed 2003/11/21 14:16

_id 58f4
authors Barequet, G. and Kumar, S.
year 1997
title Repairing CAD models
source Proceedings of IEEE Visualizationí97, pp. 363-370
summary We describe an algorithm for repairing polyhedral CAD models that have errors in their B-REP. Errors like cracks, degeneracies, duplication, holes and overlaps are usually introduced in solid models due to imprecise arithmetic, model transformations, designer's fault, programming bugs, etc. Such errors often hamper further processing like finite element analysis, radiosity computation and rapid prototyping. Our fault-repair algorithm converts an unordered collection of polygons to a shared-vertex representation to help eliminate errors. This is done by choosing, for each polygon edge, the most appropriate edge to unify it with. The two edges are then geometrically merged into one, by moving vertices. At the end of this process, each polygon edge is either coincident with another or is a boundary edge for a polygonal hole or a dangling wall and may be appropriately repaired. Finally, in order to allow user- inspection of the automatic corrections, we produce a visualization of the repair and let the user mark the corrections that conflict with the original design intent. A second iteration of the correction algorithm then produces a repair that is commensurate with the intent. Thus, by involving the users in a feedback loop, we are able to refine the correction to their satisfaction.
series other
email barequet@cs.technion.ac.il
last changed 2003/04/23 13:14

_id c57b
authors Bier, Eric A.
year 1988
title Snap-Dragging. Interactive Geometric design in Two and Three Dimensions
source University of California, Berkeley
summary Graphic artists, mechanical designers, architects, animators, authors of technical papers and others create geometric designs (illustrations and solid models) as a major part of their daily efforts. Some part of this shape construction must be done with precision. For instance, certain line segments should be horizontal, parallel or congruent. In recent years, interactive computer programs have been used to speed up the production of precise geometric designs. These programs take advantage of high-speed graphics, equation solving, and computer input peripherals to reduce the time needed to describe point positions to the machine. Previous techniques include rounding the cursor to points on a rectangular grid, solving networks of constraints, and supporting step-by-step drafting-style constructions. Snap-dragging is a modification of the drafting approach that takes advantage of powerful workstations to reduce the time needed to make precise illustrations. Using a single gravity mapping, a cursor can be snapped to either points, lines or surface. The gravity algorithm achieves good performance by computing intersection points on the fly. To aid precise construction, a set of lines, circles, planes, and spheres, called alignment objects, are constructed by the system at a set of slopes, angles, and distances specified by the user. These alignments objects are constructed at each vertex or edge that the user has declared to be hot (of interest). Vertices and edges can also be made hot by the system through the action of an automatic hotness rule. When snap-dragging is used, shapes can often be constructed using a few more keystrokes than would be needed to sketch them freehand. Objects can be edited at arbitrary orientations and sizes. The number of primitive operations is small, making it possible to provide keyboard combinations for quickly activating most of these operations. The user interface works nearly identically in two or three dimensions. In three dimensions, snap-dragging works with a two-dimensional pointing device in a single perspective view.  
series thesis:PhD
email bier@parc.com
last changed 2003/02/12 21:37

_id 8593
authors Braid, I.C.
year 1980
title Superficial Blends in Geometric Modelling
source 12 p. : ill. February, 1980. Document No. 105. includes bibliography
summary In engineering practice, many blended surfaces are both indicated and manufactured by rounding off a sharp edge. The authors term them `superficial' blends in contrast to `designed' blends for which existing surface techniques are appropriate. The provision of superficial blends in a geometric modeling system is explained, and a method is given for drawing objects containing blended edges
keywords geometric modeling, CAD, representation, solids
series CADline
last changed 2003/06/02 11:58

_id ae10
authors Branzell, Arne
year 1995
title Management of Sequential Space Experiences
source The Future of Endoscopy [Proceedings of the 2nd European Architectural Endoscopy Association Conference / ISBN 3-85437-114-4]
summary In this paper a way of combining endoscopy with architectural notations will be presented. Endoscopy is regarded as a tool to visualize sequences from a model in order to demonstrate how the environment will look like from the pedestrian’s or driver’s view. But while using it, its limitations must be considered. The model is mostly too small to present distant landmarks, districts, nodes and edges of importance. And most important, experience of space is not only visual. It is a complex process where many aspects must be taken into consideration. These aspects can be presented with architectural notations on physical drawings of the situation. The resulting “storyboard” is most useful in analyzing the situation and making better solutions possible.
keywords Architectural Endoscopy, Real Environments
series EAEA
more http://info.tuwien.ac.at/eaea/
last changed 2005/09/09 08:43

_id 819a
authors Brassel, Kurt E. and Fegeas, Robin
year 1979
title An Algorithm for Shading of Regions on Vector Display Devices
source SIGGRAPH '79 Conference Proceedings. August, 1979. vol. 13 ; no. 2: pp. 126- 133 : ill. includes bibliography
summary The display of shaded polygons by line, cross-hatch, and dot patterns on vector devices is a task frequently used in computer graphics and computer cartography. In applications such as the production of shaded maps polygon shading turns out to be critical with respect to time requirements, and the development of efficient algorithms is of importance. Given an arbitrary polygon in the plane without self-crossing edges (simply-connected polygon), the task at hand is to shade this polygon with one or two sets of parallel lines where for each set a shading angle and a line distance are given. The basic concept of this new algorithm is to decompose the polygon into a set of mutually exclusive trapezoids (in special cases triangles) where the parallel edges of the trioxides are parallel to the desired shading lines. These trapezoids and triangles are then shaded in a fast procedure. In its present form the algorithm handles regions with up to 300 islands. Possible extensions include the construction of dash and cross patterns
keywords algorithms, polygons, software, computer graphics, shading, GIS, mapping, drafting, information
series CADline
last changed 2003/06/02 11:58

_id eaea2003_11-bremer-sander
id eaea2003_11-bremer-sander
authors Bremer, S. and Sander, H.
year 2004
title View from the Road: Environmental Simulation for the Fractal City of Rhine Ruhr
source Spatial Simulation and Evaluation - New Tools in Architectural and Urban Design [Proceedings of the 6th European Architectural Endoscopy Association Conference / ISBN 80-227-2088-7], pp. 43-47
summary Highway seems to be more an issue of traffic planning than of urban design. But the highway can be a very important factor for the modern city pattern. Highways shape the spatial form of the fractal city. The modern highway can define new cores outside and “interior edges” within the city. Seen as a planning tool, highways are the great neglected opportunity in city and regional design. The 1st Architecture Biennial, 1ab, taking place from May 2003 to July 2003 in Rotterdam, explores the creative potentials of modern highways worldwide. An international research team discovered the spatial functions of highways in modern agglomerations. This lecture will give an overview of the results of the worldwide analyses and the design projects that had been undertaken. Both authors are members of the German research team. The German team examined the A 42 running through the Ruhrgebiet, a former coal and steal area in western Germany. The Ruhr Area is converting from an industrially orientated region to an agglomeration of high technology and science. But the regional image remains the same due to the fact that the changes cannot be seen, neither physically, nor from the road. Here, the highway could be used as a catalyst supporting and structuring the spatial changes to make them more legible for the people of Rhine-Ruhr. The nature becomes the most important tool of highway design. Landscape forms a linkage between the different cities of the region. Together with the A 40 and other local highways the region becomes the most important (and largest) public space of the new Rhine-Ruhr. The highway seen as a work of urban art can be designed only from the perspective of the driving car.
series EAEA
more http://info.tuwien.ac.at/eaea
last changed 2005/09/09 08:43

_id 088a
authors Brotman, Shapiro Lynne and Badler, Norman I.
year 1984
title Generating Soft Shadows With a Depth Buffer Algorithm
source IEEE Computer Graphics and Applications. October, 1984. pp. 5-12 : ill. includes bibliography
summary The authors take a pragmatic approach to shadowing and describe an algorithm that combines an existing shadowing method with a popular visible surface rendering technique, called a 'depth buffer,' to generate soft shadows resulting from light sources of finite extent. Their method extend Crow's shadow volume algorithm to produce multiple shadows overlapped to yield the characteristic soft edges of a shadow penumbra
keywords rendering, algorithms, shadowing, computer graphics
series CADline
last changed 2003/06/02 11:58

_id ecaade2017_293
id ecaade2017_293
authors D'Amico, Alessandro and Curr?, Edoardo
year 2017
title From TSL survey to HBIM, issues on survey and information modeling implementation for the built heritage - The case study of the Temple di Bacco Ravello
source Fioravanti, A, Cursi, S, Elahmar, S, Gargaro, S, Loffreda, G, Novembri, G, Trento, A (eds.), ShoCK! - Sharing Computational Knowledge! - Proceedings of the 35th eCAADe Conference - Volume 2, Sapienza University of Rome, Rome, Italy, 20-22 September 2017, pp. 39-48
summary The research presents an application of HBIM to the recovery process and design, which allows to highlight some potentialities and criticalities of what has become an important instrument in the documentation and conservation of architectural heritage. The object of the research is the Temple di Bacco, built by Lord Girmthorpe as his final resting place and located within the gardens of Villa Cimbrone, Ravello (SA).The survey has presented several difficulties due to the particular configuration of the site, very steep, with very limited space around the object. If on the one hand the TLS obvious to the lack of edges of cylindrical objects, on the other hand it poses problems for the tangency of the scan points. The Scan to BIM methodology has proven to be effective and has allowed to overcome the difficulties associated with the conformation of the artefact and of the site, in the study of the analyzed object. In conclusion, some assessments and results are reported, aimed at sharing and defining strategies and methodologies of scientific validity regarding the application of the HBIM model to a process of recovery and consolidation of an existing building object.
keywords BIM; HBIM; Built Heritage; TLS; Scan to BIM
series eCAADe
email alessandro.damico@uniroma1.it
last changed 2017/09/13 13:31

_id 19ea
authors Dallhammer, Erich
year 2003
title The IKEA Factor - Driving elements of the development of shopping centresat the edges of European metropolitan regions
source CORP 2003, Vienna University of Technology, 25.2.-28.2.2003 [Proceedings on CD-Rom]
summary A house and a garden in the suburb, a car for each adult and a TV set with minidish. On weekdays mum and dad work, the children go to school or kindergarten. On Saturdays (or Sundays) the family goes shopping to the shopping centre, where they buy what they need, have a cheap meal and can see a film or just pass the time. That seems to be the way of life for a typical middle class family in the so-called western world, or at least what sitcoms, comics, adverts and films make people believe what it normally should be. That propagated way of living strongly influences people’s and especially consumers’ behavioural patterns and consequently spatialdevelopments, which are the present challenges for urban and regional planners.
series other
email erich.dallhammer@gmx.at
last changed 2003/03/11 19:39

_id 95b9
authors Devernay, F. and Faugeras, O.
year 1995
title Automatic Calibration and Removal of Distortion from scenes of structured environments
source Proceedings of the SPIE Conference on Investigate and Trial Image Processing, 2567, SPIE, San Diego, CA, July 1995
summary Most algorithms in 3-D Computer Vision rely on the pinhole camera model because of its simplicity, whereas video optics, especially low-cost wide-angle lens, generate a lot of non-linear distortion which can be critical. To ønd the distortion parameters of a camera, we use the following fundamental property: a camera follows the pinhole model if and only if the projection of every line in space onto the camera is a line. Consequently, if we ønd the transformation on the video image so that every line in space is viewed in the transformed image as a line, then we know how to remove the distortion from the image. The algorithm consists of ørst doing edge extraction on a possibly distorted video sequence, then doing polygonal approximation with a large tolerance on these edges to extract possible lines from the sequence, and then ønding the parameters of our distortion model that best transform these edges to segments. Results are presented on real video images, compared with distortion c...
series other
last changed 2003/04/23 13:14

_id ecaade2014_054
id ecaade2014_054
authors Domenico D'Uva
year 2014
title Morphogenesis and panelling, the use of generative tools beyond academia. - Case studies and limits of the method.
source Thompson, Emine Mine (ed.), Fusion - Proceedings of the 32nd eCAADe Conference - Volume 2, Department of Architecture and Built Environment, Faculty of Engineering and Environment, Newcastle upon Tyne, England, UK, 10-12 September 2014, pp. 81-87
wos WOS:000361385100007
summary The increasing complexity in architectural design brought a parallel evolution of tools for shape generation and management. Digital tools which better fulfil this need are the generative design software. The aim of this work is finding and testing real life uses of generative design software beyond academic edges. The specific target is transform a complex surface into a similar surface mostly made of flat panels. As a testing ground it has been chosen the support in construction of complex shapes made with ordinary and well known tools. The combination of software used is Rhinoceros, with its plugin Grasshopper, and a couple of opensource add-on, Lunchbox and Paneling tool. The cases are listed from the simplest to the most complex, and the first four are solved with the automated procedure, the fifth, manually. Based on the cases studied it is possible to confirm that the method is applicable to the majority of the complex surfaces.
keywords Generative; panelling; discretization
series eCAADe
email doduva@gmail.com
last changed 2016/05/16 09:08

_id 6915
authors Dorninger, Peter
year 2003
title XML Technologies and Geodata
source CORP 2003, Vienna University of Technology, 25.2.-28.2.2003 [Proceedings on CD-Rom]
summary Photogrammetry and Remote Sensing are very important methods for acquisition of geodata. During the previous decade, severalrevolutionary changes occurred in this area. Until the appearance of automated image analysis tools, it was necessary to measureselected points in the images given. At that time, it was much faster and even cheaper to get images of real world objects compared tothe time and money consuming process of manual analyses. So one tried to minimize this effort by measuring only characteristicpoints such as edges, break-lines, peaks and valleys and, for sure, a grid with a given grid step which was selected to meet the efforts.Lots of information in the images was neglected.Digital point matching algorithms and airborne laser scanning provide many new possibilities. The only restriction on spatialresolution is the one of the used sensors. Given a more precise image sensor, the matching algorithm will be able to match moresurface points; given a higher frequency laser scanner, more points can be measured of the same area. And those sensors get moreand more precise every day. Besides, those techniques allow for fast repetition which is necessary to create time series as a basis for4D modeling! However, this fact is accompanied by several problems concerning the capability of available computers. Some years ago, as the first ideas of 3D city models arose, it was very difficult to acquire the necessary data. Today the new sensors and methods have thenecessary capability, but we are not able to handle the available datasets efficiently, because of shortcomings in the past. In a time ofworld wide data exchange through the internet and global datasets, it is necessary to have efficient methods and algorithms tomanage the available data. There is a need for international, vendor independent data exchange and management standards that haveto be accepted and supported by the industry. This article is going to present several methods of data encoding using standardized data formats based on eXtensible Markup Language (XML). After an introduction to this kind of data encoding, two derived applications for management, storage and presentation of geodata are described. As XML data is written in text format, the datasets have the ability to become rather long.Therefore some promising methods to reduce the amount of data are introduced afterwards. XML documents are mainly used fordata exchange between databases. Therefore the capabilities of commonly used database systems for storage of geodata are describedin the end and current implementation results of the Institute of Photogrammetry and Remote Sensing (I.P.F.) are presented.
series other
email pdo@ipf.tuwien.ac.at
last changed 2003/03/11 19:39

_id 6890
authors Eastman, Charles M. and Weiler, Kevin
year 1979
title Geometric Modeling Using the Euler Operators
source 12 p. : ill. Pittsburgh: Institute of Physical Planning, Carnegie Mellon University, February, 1979. includes bibliography
summary A recent advance in the modeling of three-dimensional shapes is the joint development of bounded shape models, capable of representing complete and well-formed arbitrary polyhedra, and operators for manipulating them. Two approaches have been developed thus far in forming bounded shape models: to combine a given fixed set of primitive shapes into other possibly more complex ones using the spatial set operators, and/or to apply lower level operators that define and combine faces, edges, loops and vertices to directly construct a shape. The name that has come to be applied to these latter operators is the Euler operators. This paper offers a description of the Euler operators, in a form expected to be useful for prospective implementers and others wishing to better understand their function and behavior. It includes considerations regarding their specification in terms of being able to completely describe different classes of shapes, how to properly specify them and the extent of their well-formedness, especially in terms of their interaction with geometric operations. Example specifications are provided as well as some useful applications. The Euler operators provide different capabilities from the spatial set operators. An extensible CAD/CAM facility needs them both
keywords Euler operators, boolean operations, CSG, geometric modeling, CAD, CAM, B-rep, solid modeling, theory
series CADline
email chuck.eastman@arch.gatech.edu
last changed 2003/05/17 08:15

_id ea0f
authors El Araby, Mostafa and Okiel, Ahmed
year 2003
title The Use of Virtual Reality in Urban Design: Enhancing the Image of Al-Ain City, UAE
source CORP 2003, Vienna University of Technology, 25.2.-28.2.2003 [Proceedings on CD-Rom]
summary This study aims at exploring the rapid growth of the use of Virtual Reality techniques in the field of Urban Design with application to the Al-Ain City. Currently, Virtual Reality and Virtual Environments are the most growing fields of information technology and have a great media attention. There is evidence to suggest that the use of such technology will enhance conceivable image of any proposed project at any urban setting for users, designers and clients. Therefore, city officials and administrators (clients) and the public (users) can reach better decisions regarding proposed projects within their towns and cities. Because of the limited time and resources, this study examines the visual quality of Downtown Al Ain, UAE, specifically, the Khalifa street (major shopping street). A basic VRmodel to the street was constructed. Modifications to the basic model were made to examine how changes in buildings’ heights and street vegetation affect the visual quality of the street. Results of this study showed that urban visualization is proving to be a valuable tool for designers and planners. Increasing the heights of buildings in the mid-street and on the edges, along with enforcing distinctive architectural styles for the proposed buildings will enhance the overall quality of the street. Furthermore, decreasing the intensity of current vegetation and tree heights will increase the imaginable quality of the street. Nevertheless, the built of a comprehend VR model needs more time, resources and facilities that were not available to this study. This model, if completed, tothe whole downtown area can be used both to identify existing problems and to quickly evaluate alternative solutions to those problems.
series other
email melaraby@uaeu.ac.ae
last changed 2003/03/11 19:39

_id 4104
authors Ervin, Stephen McTee
year 1989
title The structure and function of diagrams in environmental design :a computational inquiry
source Massachusetts Institute of Technology
summary The design process often begins with a graphical description of the proposed device or system and sketching is the physical expression of the design engineer's thinking process. Computer Aided Design is a technique in which man and machine are blended into a problem solving team, intimately coupling the best characteristics of each. Solid modelling is developed to act as the common medium between man and the computer. At present it is achieved mainly by designing with volumes and hence does not leave much room for sketching input, the traditional physical expression of the thinking process of the design engineer. This thesis describes a method of accepting isometric free hand sketching as the input to a solid model. The design engineer is allowed to make a sketch on top of a digitizer indicating (i) visible lines; (ii) hidden lines; (iii) construction lines; (iv) centre lines; (v) erased lines; and (vi) redundant lines as the input. The computer then processes this sketch by identifying the line segments, fitting the best possible lines, removing the erased lines, ignoring the redundant lines and finally merging the hidden lines and visible lines to form the lines in the solid in an interactive manner. The program then uses these lines and the information about the three dimensional origin of the object and produces three dimensional information such as the faces, loops, holes, rings, edges and vertices which are sufficient to build a solid model. This is achieved in the following manner. The points in the sketch are first written into a file. The computer than reads this file, breaks the group of points into sub-groups belonging to individual line segments, fits the best lines and identify the vertices in two dimensions. These improved lines in two dimensions are then merged to form the lines and vertices in the solid. These lines are then used together with the three dimensional origin (or any other point) to produce the wireframe model in three dimensions. The loops in the wireframe models are then identified and surface equations are fitted to these loops. Finally all the necessary inputs to build a B-rep solid model are produced.
series thesis:PhD
email servin@gsd.harvard.edu
last changed 2003/02/12 21:37

_id 6a59
authors Franklin, Randolph
year 1980
title A Linear Time Exact Hidden Surface Algorithm
source SIGGRAPH '80 Conference Proceedings. July, 1980. vol. 14 ; no. 3: pp. 117-133 : ill. includes bibliography
summary This Paper presents a new hidden surface algorithm. Its output is the set of the visible pieces of edges and faces, and is as accurate as the arithmetic precision of the computer. Thus calculating the hidden surfaces for a higher resolution device takes no more time. If the faces are independently and identically distributed, then the execution time is linear in the number of faces. In particular, the execution time does not increase with the depth complexity. This algorithm overlays a grid on the screen whose fineness depends on the number and size of the faces. Edges and faces are sorted into grid cells. Only objects in the same cell can intersect or hide each other. Also, if a face completely covers a cell then nothing behind it in the cell is relevant. Three programs have tested this algorithm. The first verified the variable grid concept on 50,000 intersecting edges. The second verified the linear time, fast speed, and irrelevance of depth complexity for hidden lines on 10,000 spheres. This also tested depth complexities up to 30, and showed that perspective scenes with the farther objects smaller are even faster to calculate. The third verified this for hidden surfaces on 3,000 squares
keywords hidden surfaces, algorithms, hidden lines, variables, grids, computer graphics, programming
series CADline
last changed 2003/06/02 11:58

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