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 14 of 14

_id 473f
authors Bartnicka, Malgorzata
year 1998
title The Influence of Light upon the Spatial Perception of Image
source Cyber-Real Design [Conference Proceedings / ISBN 83-905377-2-9] Bialystock (Poland), 23-25 April 1998, pp. 21-26
summary With regard to mental perception, light is one of the basic and strongest experiences influencing man. It is a phenomenon unchanged since the beginning of human kind, regardless of the fact what form or shape it was transmitted in. We are so used to light that we have stopped noticing how much we owe to it. It is the basic source and condition of our visual perception. Without light, illumination, we would not be able to see anything as it is light that transmits the shapes, distances and colours seen by us. The light which we perceive is a specific sight stimulus. It constitutes of only a small range of the spectrum of electromagnetic radiation existing in nature. The visible radiation encompasses the wave length from 400 to 800 nm. When the whole range of the visible wave spectrum enters the eye, the impression of seeing white light is produced. The light rays entering the sight receptors are subject to reflection, absorption and transmission. In the retina of the eye, the light energy is transformed into nerve impulses. The reception of light is dependent on the degree of absorption of the length of certain waves and the concentration of light. A ray of light entering the eye pupil is the proper eye stimulus which stimulates the receptors of the retina and causes visual impressions.
series plCAD
last changed 1999/04/08 15:16

_id f9f4
authors Cook, R.L., Porter, Th. and Carpenter, L.
year 1984
title Distributed Ray Tracing
source Computer Graphics, vol. 18, no. 3, pp. 137145, July 1984. SIGGRAPH '84 Proceedings
summary Ray tracing is one of the most elegant techniques in computer graphics. Many phenomena that are difficult or impossible with other techniques are simple with ray tracing, including shadows, reflections, and refracted light. Ray directions, however, have been determined precisely, and this has limited the capabilities of ray tracing. By distributing the directions of the rays according to the analytic function they sample, ray tracing can incorporate fuzzy phenomena. This provides correct and easy solutions to some previously unsolved or partially solved problems, including motion blur, depth of field, penumbras, translucency, and fuzzy reflections. Motion blur and depth of field calculations can be integrated with the visible surface calculations, avoiding the problems found in previous methods.
series journal paper
last changed 2003/04/23 13:14

_id sigradi2007_af07
id sigradi2007_af07
authors Culagovski, Rodrigo
year 2007
title Three dimensional isovist analysis method [Método de Análisis Tridimensional con isovistas]
source SIGraDi 2007 - [Proceedings of the 11th Iberoamerican Congress of Digital Graphics] México D.F. - México 23-25 October 2007, pp. 174-176
summary This paper presents a three dimensional method of isovist analysis implemented in the MaxScript programming language. The script accepts as its input a standard three dimensional model of the buildings and terrain being analyzed, upon which a N×N grid is projected. Each square of this grid is assigned a height value, thereby producing a simplified surface description which is amenable to mathematical analysis. A three dimensional isovist is then generated for each grid square, by placing an observation point 1.5 meters above its center and finding the intersection of a series of rays from this point to the input model. The distance from the observation point to the intersection is summed over for all the angles studied giving a compound isovist measurement for the grid square under consideration.
keywords Isovist; viewshed; analysis; model; volumetric; visibility
series SIGRADI
last changed 2016/03/10 08:49

_id 9e26
authors Do, Ellen Yi-Luen,
year 1999
title The right tool at the right time : investigation of freehand drawing as an interface to knowledge based design tools
source College of Architecture, Georgia Institute of Technology
summary Designers use different symbols and configurations in their drawings to explore alternatives and to communicate with each other. For example, when thinking about spatial arrangements, they draw bubble diagrams; when thinking about natural lighting, they draw a sun symbol and light rays. Given the connection between drawings and thinking, one should be able infer design intentions from a drawing and ultimately use such inferences to program a computer to understand our drawings. This dissertation reports findings from empirical studies on drawings and explores the possibility of using the computer to automatically infer designer's concerns from the drawings a designer makes. This dissertation consists of three parts: 1) a literature review of design studies, cognitive studies of drawing and computational sketch systems, and a set of pilot projects; 2) empirical studies of diagramming design intentions and a design drawing experiment; and 3) the implementation of a prototype system called Right-Tool-Right-Time. The main goal is to find out what is in design drawings that a computer program should be able to recognize and support. Experiments were conducted to study the relation between drawing conventions and the design tasks with which they are associated. It was found from the experiments that designers use certain symbols and configurations when thinking about certain design concerns. When thinking about allocating objects or spaces with a required dimensions, designers wrote down numbers beside the drawing to reason xviii about size and to calculate dimensions. When thinking about visual analysis, designers drew sight lines from a view point on a floor plan. Based on the recognition that it is possible to associate symbols and spatial arrangements in a drawing with a designer's intention, or task context, the second goal is to find out whether a computer can be programed to recognize these drawing conventions. Given an inferred intention and context, a program should be able to activate appropriate design tools automatically. For example, concerns about visual analysis can activate a visual simulation program, and number calculations can activate a calculator. The Right- Tool-Right-Time prototype program demonstrates how a freehand sketching system that infers intentions would support the automatic activation of different design tools based on a designers' drawing acts.
series thesis:PhD
last changed 2004/10/04 05:49

_id afe6
authors Funkhouser, Thomas
year 2001
title Modeling acoustics in virtual environments using the uniform theory of diffraction
source Siggraph 2001
summary Realistic modeling of reverberant sound in 3D virtual worlds provides users with important cues for localizing sound sources and understanding spatial properties of the environment. Unfortunately, current geometric acoustic modeling systems do not accurately simulate reverberant sound. Instead, they model only direct transmission and specular reflection, while diffraction is either ignored or modeled through statistical approximation. However, diffraction is important for correct interpretation of acoustic environments, especially when the direct path between sound source and receiver is occluded. The Uniform Theory of Diffraction (UTD) extends geometrical acoustics with diffraction phenomena: illuminated edges become secondary sources of diffracted rays that in turn may propagate through the environment. In this paper, we propose an efficient way for computing the acoustical effect of diffraction paths using the UTD for deriving secondary diffracted rays and associated diffraction coefficients. Our main contributions are: 1) a beam tracing method for enumerating sequences of diffracting edges efficiently and without aliasing in densely occluded polyhedral environments; 2) a practical approximation to the simulated sound field in which diffraction is considered only in shadow regions; and 3) a real-time auralization system demonstrating that diffraction dramatically improves the quality of spatialized sound in virtual environments.
series other
last changed 2003/04/23 13:50

_id 2647
authors Koutamanis, Alexander
year 1994
title Sun and Time in the Built Environment
source The Virtual Studio [Proceedings of the 12th European Conference on Education in Computer Aided Architectural Design / ISBN 0-9523687-0-6] Glasgow (Scotland) 7-10 September 1994, p. 248
summary At a time when requirements on the quality of the built environment are increasingly becoming explicit and specific, computer technology promises the ability to analyse and evaluate buildings during the design process. The computer can extract the necessary information from conventional geometric representations, generate comprehensive descriptions of the aspects to be analysed and use these to arrive at precise and accurate results that can be represented visually. Visual representations facilitate comprehension of the analyses and of their results because of their agreement with our predominantly visual perception of the built environment. The consequent close correspondences between geometric design representations and the visual representation of analyses and evaluations allow direct correlation of the results with the design as a whole. Such correlation is instrumental for imposing explicit and justifiable constraints on the further development of a design. One good example of visual analyses is daylighting. In many drafting and modelling programs a viewing point can be set on the basis the sun’s height and azimuth. The projection returned reveals the surfaces that are directly lit by the sun. In other programs the sun’s height and azimuth can be used to position a light source with parallel rays. This source gives rise to shading and shadows that correspond to the ones produced by the sun. In addition, several programs can calculate the position of the sun and hence the viewing point or the light source on the basis of the date, the time and the geographic coordinates of the place. The availability of computer-aided daylighting analysis has obvious advantages for practice. Efficiency and reliability of the analysis increase, while flexibility is superior to analog simulations. Unfortunately automation of daylighting analysis may also impede understanding of underlying principles, that is, of the issues at the focus of architectural education. Explaining how the analysis is performed and why becomes thus a necessity for computer-aided design education. Exercises that aim at more than just learning and using a computer program can enrich the student’s understanding of the analysis and its results. The efficiency and flexibility of the computer facilitate the study of aspects such as the comparison of local apparent time, local mean time, standard time and daylight saving time and their significance for daylighting, solar heating and cooling patterns and possibilities. Sundials with their explicit correspondence to solar movement can be instrumental in this respect. The efficiency and flexibility of the computer also support the investigation of the techniques by which the daylighting analysis is performed and explain the relationships between projective theory, sciagraphy and computer graphics. A better understanding of the principles and techniques for daylighting analysis has a generally positive influence on the students’ learning of the daylighting analysis software and more significantly on their correlation of daylighting constraints with their designs. This leads in turn to increased flexibility and adaptability of the designs with respect to daylighting and to a conscious and meaningful exploration of variations and alternative solutions.
series eCAADe
last changed 2003/05/16 19:27

_id 999e
id 999e
authors KOUZELEAS Stelios
year 2004
source Acoustics 2004, Hellenic Institute of Acoustics (HELINA), Aristotle University of Thessaloniki, 27-28 September 2004, Greece
summary (pdf file in greek)- With the aid of the acoustic simulation plate-form named « CAD-Acoustic » which is developed in the context of PhD and adapted on the AutoCAD system, this paper presents the halls acoustic results (RT60) of Elmia (Sweden) and Opera of Bordeaux (France) in relation to acoustic measurements and results of other acoustic simulation software (Odeon, Epidaure). In parallel, it presents geometrical simulations of the modelised halls’ acoustic behavior, such as the 3D reflections of the acoustic rays from selected surface, the 3D view of the materials’ arrangements through surfaces’ coloring, the measurement of the selected absorbing / reflecting surfaces in m2 and the individual or massive absorption coefficients’ assignment to the surfaces. Finally, with the aid of « CAD-Acoustic » the acoustic results are compared in a graphic manner in relation to the ideal acoustic rates, a presentation which is a kind of an “ architectural translation of the acoustic results” taking into account several architectural elements.
keywords CAD modeling, "CAD-Acoustic" software developement, Architectural acoustic simulation
series other
type normal paper
last changed 2005/10/25 09:22

_id 4604
authors Laveau, S. and Faugeras, O.
year 1994
title 3D Scene Representation as a Collection of Images and Fundamental Matrices
source INRIA Report
summary The problem we solve in this paper is the following. Suppose we are given N views of a static scene obtained from different viewpoints, perhaps with different cameras. These viewpoints we call reference viewpoints since they are all we know of the scene. We would like to decide if it is possible to predict ano- ther view of the scene taken by a camera from a viewpoint which is arbitrary and a priori di erent from all the reference viewpoints. One method for doing this would be to use these viewpoints to construct a three-dimensional repre- sentation of the scene and reproject this representation on the retinal plane of the virtual camera. In order to achieve this goal, we would have to establish some sort of calibration of our system of cameras, fuse the three-dimensional representations obtained from, say, pairs of cameras thereby obtaining a set of 3-D points, the scene. We would then have to approximate this set of points by surfaces, a segmentation problem which is still mostly unsolved, and then intersect the optical rays from the virtual camera with these sur- faces. This is the most straightforward way of going from a set of images to a new image using the current computer vision paradigm of rst building a three-dimensional representation of the environment from which the rest is derived. We do not claim that there does not exist any simpler way of using the three-dimensional representation than the one we just sketched, but this is just simply not our point. Our point is that it is possible to avoid entirely the explicit three-dimensional reconstruction process: the scene is represented by its images and by some ba- sically linear relations that govern the way points can be put in correspondence between views when they are the images of the same scene-point. These images and their algebraic relations are all we need for predicting a new image. This approach is similar in spirit to the one that has been used in trinocular stereo. Hypotheses of correspondences between two of the images are used to predict features in the third. These predictions can then be checked to validate or inva- lidate the initial correspondence. This approach has proved to be quite e cient and accurate. Related to these ideas are those develo- ped in the photogrammetric community under the name of transfer methods which nd for one or more image points in a given image set, the corresponding points in some new image set.
series report
last changed 2003/04/23 13:50

_id acadia11_396
id acadia11_396
authors Lim, Jason
year 2011
title Let’s Work Together: A Stigmergic Approach to Acoustic Design
source ACADIA 11: Integration through Computation [Proceedings of the 31st Annual Conference of the Association for Computer Aided Design in Architecture (ACADIA)] [ISBN 978-1-6136-4595-6] Banff (Alberta) 13-16 October, 2011, pp. 396-403
summary This paper explores the application of agent-based modeling techniques to the domain of acoustics design. Concepts derived from Stigmergy, which is a class of mechanisms that mediate interactions between social organisms, are applied to a custom implementation of a raytracing based acoustics simulator. Rays are given the agency of changing the geometric and material properties of the surfaces they come in contact with during the raytracing phase. The acoustic simulation process is an active one, where the modeled room environment is adapted while being evaluated. Given performance criteria as input, the simulation process is applied to an auditorium example. The auditorium is adapted and its eventual emergent design has improved acoustic performance. It is hoped that this work will demonstrate the potential of coupling multi-agent systems with simulation processes in order to create new design tools.
series ACADIA
type work in progress
last changed 2011/10/06 04:05

_id 6d19
authors Reggini, Horacio C.
year 1974
title A Computer Program for Drawing Non- Classical Perspectives
source International Conference and Exhibition on Computers in Engineering and Building Design September, 1974. 5 p. ; [2]p. of ill.
summary This article deals with a new way of portraying a three- dimensional object on a two-dimensional plane surface. In classical perspective each point of an object or scene is projected upon a plane by means of a bundle of straight projection rays departing from a unique point or point of view. The author proposes a similar procedure except that the straight projection rays of classical perspective are replaced with special curved ones
keywords drawings, perspective, computer graphics
series CADline
last changed 2003/06/02 11:58

_id 05b8
authors Reggini, Horacio C.
year 1975
title Perspective Using Curved Projection Rays and its Computer Application
source Leonardo. England: Pergamon Press, 1975. vol. 8: pp. 307-312 : ill. includes bibliography
summary The author describes a novel way for generating line drawings of 3-dimensional objects and describes a computer program that he used in plotting such drawings. Instead of being confined by the rules of linear perspective, which governs retinal and photographic images, he employs a more general mathematical model that provides a family of perspectives. Each member of the family is designated individually by a numerical value (between 0 and 1) for its index i. The lowest value, i=0, leads to the linear equation that applies to linear perspective; application of the highest value, i=1, results in axonometric projection. Sometimes linear perspective leads to a drawing or to a photographic image that seems grossly distorted in comparison with what one perceives in looking at an object. The author's method, employed with fractional values for i and with the same viewpoint, may be used to produce more acceptable drawings
keywords drawings, perspective, rendering, computer graphics, projective geometry
series CADline
last changed 2003/06/02 11:58

_id 028f
authors Reggini, Horacio C.
year 1976
title A Generalized Perspective Involving Visual Size Constancy
source Estudos Cognitivos. San-Paulo, Argentine: December, 1976. vol. 1: pp. [71]-101 : ill. Written in spanish. --- includes bibliography
summary This article deals with a new idea for generating plane representation figures of three dimensional objects and describes a corresponding computer program. Instead of using the classical perspective rules that govern retinal images as well as common cameras, a different projection method is elaborated based upon the use of a particular kind of curved projection rays instead of the usual straight ones. Curvature of projection lines is made depending on an index variable between zero and one. Meanwhile conical and parallel classical images are obtained for the limit values, compromise images result with intermediate values. Fundamentals, analytical procedure and program for displaying images are presented. Finally, examples are shown and the development possibility of a new type of camera with the property of producing pictures according to different indexes is raised
keywords computer graphics, perspective, rendering, systems
series CADline
last changed 2003/06/02 11:58

_id 7670
authors Sawicki, Bogumil
year 1995
title Ray Tracing – New Chances, Possibilities and Limitations in AutoCAD
source CAD Space [Proceedings of the III International Conference Computer in Architectural Design] Bialystock 27-29 April 1995, pp. 121-136
summary Realistic image synthesis is nowadays widely used in engineering applications. Some of these applications, such as architectural, interior, lighting and industrial design demand accurate visualization of non-existent scenes as they would look to us, when built in reality. This can only be archived by using physically based models of light interaction with surfaces, and simulating propagation of light through an environment. Ray tracing is one of the most powerful techniques used in computer graphics, which can produce such very realistic images. Ray tracing algorithm follows the paths of light rays backwards from observer into the scene. It is very time consuming process and as such one could not be developed until proper computers appeared, In recent years the technological improvements in computer industry brought more powerful machines with bigger storage capacities and better graphic devices. Owing to increasing these hardware capabilities successful implementation of ray tracing in different CAD software became possible also on PC machines. Ray tracing in AutoCAD r.12 - the most popular CAD package in the world - is the best of that example. AccuRender and AutoVision are an AutoCAD Development System (ADS) applications that use ray tracing to create photorealistic images from 3D AutoCAD models. These ,internal"' applications let users generate synthetic images of threedimensional models and scenes entirely within AutoCAD space and show effects directly on main AutoCAD screen. Ray tracing algorithm accurately calculates and displays shadows, transparency, diffusion, reflection, and refraction from surface qualities of user-defined materials. The accurate modelling of light lets produce sophisticated effects and high-quality images, which these ray tracers always generates at 24-bit pixel depth,"providing 16,7 million colours. That results can be quite impressive for some architects and are almost acceptable for others but that coloured virtual world, which is presented by ray tracing in AutoCAD space in such convincing way, is still not exactly the same as the real world. Main limitations of realism are due to the nature of ray tracing method Classical ray tracing technique takes into account the effects of light reflection from neighbouring surfaces but, leaves out of account the ambient and global illumination arising out of complex interreflections in an environment. So models generated by ray tracing belong to an "ideal" world where real materials and environment can't find their right place. We complain about that fact and say that ray tracing shows us "too specular world", but (...) (...) there is anything better on the horizon? It should be concluded, that typical abilities of today's graphics software and hardware are far from exploited. As was observed in literature there have been various works carried along with the explicit intention of overcoming all these ray tracing limitations, These researches seem to be very promising and let us hope that their results will be seen in CAD applications soon. As it happens with modelling, perhaps the answer will come from a variety of techniques that can be combined together with ray tracing depending on the case we are dealing with. Therefore from the point of view of an architects that try to keep alive some interest on the nature of materials and their interaction with form, "ray tracing" seems to be right path of research and development that we can still a long way follow, From the point of view of the school, a critical assimilation of "ray tracing" processes is required and one that might help to determinate exactly their distortions and to indicate the correct way of its development and right place in CAAD education. I trust that ray tracing will become standard not only in AutoCAD but in all architectural space modelling CAD applications and will be established as a powerful and real tool for experimental researches in architectural design process. Will be the technological progress so significant in the nearest future as it is anticipated?
series plCAD
last changed 2000/01/24 09:08

_id caadria2011_008
id caadria2011_008
authors Yuan, Xiaofang; Jihyun Lee and Yu Wu
year 2011
title A new perspective to look at ice-ray grammar
source Proceedings of the 16th International Conference on Computer Aided Architectural Design Research in Asia / The University of Newcastle, Australia 27-29 April 2011, pp. 81-90
summary Chinese lattice designs are a rich source of interesting geometric forms and shape grammar has been used to analyze and generate Chinese lattice designs. Following the origin design intention, researchers have already defined simple and intuitively compelling shape grammar rules to generate them. However, for some self-similar ice-rays, it is difficult to clarify the design intention of them, which is why researchers still cannot define shape grammar rules for them. In this paper, we utilize the culture hints to select the lowest-level constituent for shape calculation and clarify the design intention embedded in the ice-rays. We develop our new shape grammar rules based on the design intention and validate the rules by generating an existing ice-ray window.
keywords Ice-ray; shape grammar; cultural hint; design intention; lowest-level constituent
series CAADRIA
last changed 2012/05/30 19:29

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