Cumincad : CUMINCAD Papers : Search Results

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

PDF papers
References

Hits 1 to 10 of 10

Reformat results as: short short into frame detailed detailed into frame

_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	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	2928
authors	Barsky, Brian A. and De Rose, Tony D.
year	1985
title	The Beta2-spline : A Special Case of the Beta-spline Curve and Surface Representation
source	IEEE Computer Graphics and Applications September, 1985. vol. 5: pp. 46-58 : ill. includes bibliography.
summary	This article develops a special case of the Beta-spline curve and surface technique called the Beta2-spline. While a general Beta-spline has two parameters (B1 and B2) controlling its shape, the special case presented here has only the single parameter B2. Experience has shown this to be a simple but very useful special case that is computationally more efficient than the general case. Optimized algorithms for the evaluation of the Beta2-spline basis functions and rendering of Beta2-spline curves and surfaces via subdivision are presented. This technique is proving to be quite useful in the modeling of complex shapes. The representation is sufficiently general and flexible so as to be capable of modeling irregular curved-surface objects such as automobile bodies, aircraft fuselages, ship hulls, turbine blades, and bottles
keywords	B-splines, curved surfaces, computational geometry, representation, algorithms, computer graphics, rendering
series	CADline
last changed	2003/06/02 14:41

_id	29ff
authors	Farouki, Rida T. and Hinds, John K.
year	1985
title	A Hierarchy of Geometric Forms
source	IEEE Computer Graphics and Applications. May, 1985. vol. 5: pp. 51-78 : ill. includes bibliography
summary	This article describes a unified approach to geometric modeling based on the mathematics of parametric polynomial functions. Such a unified scheme for geometric representation and computation provides a natural base for a geometric modeler of considerable versatility and robustness
keywords	geometric modeling, parametrization, representation, curves, curved surfaces, B-splines
series	CADline
last changed	2003/06/02 13:58

_id	4839
authors	Kripac, Jiri
year	1985
title	Classification of Edges and its Application in Determining Visibility
source	Computer Aided Design. January/ February 1985. vol. 17: pp.30-36 : ill. includes bibliography
summary	A new hidden-line algorithm is proposed for illustrating objects consisting of plane faces. The algorithm determines the degree of edge and classifies edges and faces into contoural and non-contoural. To reduce memory requirements, sequential files and sorting are used. The algorithm is particularly intended for illustrating complex objects, such as curved surfaces approximated by plane faces
keywords	algorithms, hidden lines, curved surfaces, geometric modeling, computer graphics
series	CADline
last changed	1999/02/12 15:08

_id	e11a
authors	Nishita, Tomoyuki and Nakamae, Eihachiro
year	1985
title	Continuous Tone Representation of Three-Dimensional Objects Taking Account of Shadows and Interreflection
source	SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 23-30 : ill. some col. includes bibliography
summary	The effect of shadows and interreflection created by room obstructions is an important factor in the continuous tone representation of interiors. For indirect illumination, in most cases a uniform ambient light has been considered, even though the interreflection gives very complex effects with the shaded images. The proposed method for indirect lighting with shadows results in the following advanced points: (1) The indirect illuminance caused by the surfaces of objects such as ceilings, floors, walls, desks, bookcases etc. gives added realism to images. (2) The proposed method is suitable for every type of light source such as point sources, linear sources, and area sources
keywords	shadowing, shading, computer graphics, display, rendering, architecture, lighting
series	CADline
last changed	2003/06/02 13:58

_id	85d0
authors	Peachey, Darwyn R.
year	1985
title	Solid Texturing of Complex Surfaces
source	SIGGRAPH '85 Conference Proceedings. July, 1985. vol. 19 ; no. 3: pp. 279-286 : ill. includes bibliography
summary	Texturing is an effective method of simulating surface detail at relatively low cost. Traditionally, texture functions have been defined on the two-dimensional surface coordinate systems of individual surface patches. This paper introduces the notion of 'solid texturing.' Solid texturing uses texture functions defined throughout a region of three-dimensional space. Many nonhomogeneous materials, including wood and stone, may be more realistically rendered using solid texture functions. In addition, solid texturing can easily be applied to complex surfaces which are difficult to texture using two- dimensional texture functions. The paper gives examples of solid texture functions based on Fourier synthesis, stochastic texture models, projections of two-dimensional textures, and combinations of other solid textures
keywords	shading, texture mapping, solid modeling, objects, computer graphics, rendering, visualization
series	CADline
last changed	2003/06/02 10:24

_id	2699
authors	Piegl, L.
year	1985
title	Recursive Algorithms for the Representation of Parametric Curves and Surfaces
source	Computer Aided Design Butterworth & Co. (publishers) Ltd., June, 1985. vol. 17: pp. 225-230 : ill.
summary	includes a short bibliography. Recursive algorithms for the representation of parametric curves and surfaces are presented which are based upon a geometric property of the de Casteljau algorithm. The algorithms work with triangular and pyramidal arrays that provide an easy handing of the curve and the surface 'in a large' design
keywords	representation, recursion, algorithms, parametrization, curves, curved surfaces
series	CADline
last changed	2003/06/02 13:58

_id	4f7a
authors	Piegl, L.
year	1985
title	The Sphere as a Rational Bezier Surface
source	[4], 18 p. : ill. October, 1985. Preprint No. 07-13. includes bibliography
summary	A method is developed for the efficient representation of spherical caps by using the rational Bezier scheme of Computer Aided Design. The technique is applied to describe special spherical patches such as the hemi-sphere, an octant of a sphere and the whole sphere. A geometric interpretation of quadratic curves and quadric patches is used in order to obtain an insight into the geometry inherent in the rational Bezier scheme and so to make easier the selection of the spherical patch out of the quadric primitives
keywords	Bezier, curved surfaces, CAD
series	CADline
last changed	2003/06/02 13:58

_id	a0d4
id	a0d4
authors	Rosa Enrich, Andrea Carnicero, Gustavo Fornari & Pedro Orazzi
year	2004
title	ANALYSIS AND EVALUATION OF MATHEMATICAL LEARNING STRUCTURES
source	Proceedings of the Fourth International Conference of Mathematics & Design, Spetial Edition of the Journal of Mathematics & Design, Volume 4, No.1, pp. 13-21.
summary	Abstract: A series of practical tasks have been done under the general name of “Surfaces in invisible cities”. Each task was based on a story taken from the book The Invisible Cities by Italo Calvino. The research carried out allows to design a pedagogical project which makes evident , generates and connects several intentions, motivations and learning structures. It proposes the use of multi- level languages and readings. Therefore, each task takes more time than that of the proposed mathematical class. Its implementation generates a broader view than that seen at the time of design. From the detailed analysis of the results obtained, the following diverse pedagogical aspects of this work project arise: a. The use of several multiple intelligence: Howard Gardner (1985) found that a man has several distinct intelligence types among which Logical-Mathematical; Spatial; Linguistic -oriented; Musical; Intra-personal; Kinesthetic-Corporal; Interpersonal stand out. Only those types used in the task will be analyzed, making a brief description of each type. b. The architectonic-city planning aspects: architectonic-city planning interpretation of the space imagined after reading the text, with the purpose of identifying figures, shapes, volumes and colors which are expressed via an analogous space. They consist of visual, architectonic and territorial speculations without a rigorous spatial theory and it is pretended that they possess a technical precision at mathematical concept level. c. The mathematical contents: a study of the conical and square shapes present in the designs done and used in a creative manner in students’ compositions following the reading of the story chosen is carried out. An analysis of shapes is performed and mathematical problems are posed within the design context. Traditional sketching methods have been used in task solving and the possibilities offered by the virtual tools are analyzed. Emphasis has been put on the vertical and horizontal interchanges in the Chair, generating changes in knowledge transmission perspectives, thus allowing the sharing of contents, abilities and resources. The architectonic work imagined and created by the students will focus on these different working lines creating a harmonious and significant whole. The work is the result of multiple connections and creative proposals.
keywords	city, geometry, multiple intelligence
series	other
type	normal paper
email
last changed	2005/04/07 12:46

No more hits.