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CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
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_id	8a88
authors	Anderson, David P.
year	1982
title	Hidden Line Elimination in Projected Grid Surfaces
source	ACM Transactions on Graphics. October, 1982. vol. 1: pp. 274-288 : ill. includes a short bibliography
summary	The hidden line and hidden surface problems are simpler when restricted to special classes of objects. An example is the class of grid surfaces, that is, graphs of bivariate functions represented by their values on a set of grid points. Projected grid surfaces have geometric properties which permit hidden line or hidden surface elimination to be done more easily than in the general case. These properties are discussed in this paper, and an algorithm is given which exploits them
keywords	algorithms, hidden lines, hidden surfaces, grids, computer graphics
series	CADline
last changed	2003/06/02 10:24

_id	a426
authors	Barsky, Brian A. and Greenberg, Donald P.
year	1982
title	Interactive Surface Representation System Using a B-spline Formulation with Interpolation Capability
source	computer Aided Design. July, 1982. vol. 14: pp. 187-194 : col.ill. includes bibliography
summary	An interactive surface representation system is described which uses a parametric uniform bicubic B-spline formulation which can describe a surface initially defined to interpolate a specified network of points
keywords	CAD, curved surfaces, computational geometry, interpolation, B-splines
series	CADline
last changed	2003/06/02 13:58

_id	6094
authors	Blinn, J.I.
year	1982
title	A Generalization of Algebraic Surface Drawing
source	ACM Transaction on Graphics, vol. 1, no. 3, pp. 235-256, 1982
summary	The technology of creating realistic and visually interesting images of three- dimensional shapes is advancing on many fronts. One such front is the develop- ment of algorithms for drawing curved surfaces directly from their mathematical definitions rather than by dividing them into large numbers of polygons. Two classes of surfaces which have received attention are the quadric and the bivariate parametric surfaces. Bivariate parametric surfaces are generated by three func- tions of two variables (most popularly polynomials), as the variables take on different values. Algorithms dealing with such surfaces are due to Catmull; Lane, Carpenter, Whitted and Blinn; and Clark.
series	journal paper
last changed	2003/11/21 15:16

_id	c1bf
authors	Gouraud, H.
year	1982
title	Continuous shading of curved surfaces
source	IEEE Transactions on Computers, 20, no. 6, 623-629
summary	A procedure for computing shaded pictures of curved surfaces is presented. The surface is approximated by small polygons in order to solve easily the hidden-parts problem, but the shading of each polygon is computed so that the discontinuities of shade are eliminated across the surface and a smooth appearance is obtained. In order to achieve speed efficiency, the technique developed by Watkins is used which makes possible a hardware implementation of this algorithm.
series	journal paper
last changed	2003/04/23 15:14

_id	8c27
authors	Kalay, Yehuda E.
year	1982
title	Determining the Spatial Containment of a Point in General Polyhedra
source	Computer graphics and Image Processing. 1982. vol. 19: pp. 303-334 : ill. includes bibliography. See also criticism and improvements in Orlowski, Marian
summary	Determining the inclusion of a point in volume-enclosing polyhedra (shapes) in 3D space is, in principle, the extension of the well-known problem of determining the inclusion of a point in a polygon in 2D space. However, the extra degree of freedom makes 3D point-polyhedron containment analysis much more difficult to solve than the 2D point polygon problem, mainly because of the nonsequential ordering of the shape elements, which requires global shape data to be applied for resolving special cases. Two general O(n) algorithms for solving the problem by reducing the 3D case into the solvable 2D case are presented. The first algorithm, denoted 'the projection method,' is applicable to any planar- faced polyhedron, reducing the dimensionality by employing parallel projection to generate planar images of the shape faces, together with an image of the point being tested for inclusion. The containment relationship of these images is used to increment a global parity-counter when appropriate, representing an abstraction for counting the intersections between the surface of the shape and a halfline extending from the point to infinity. An 'inside' relationship is established when the parity-count is odd. Special cases (coincidence of the halfline with edges or vertices of the shape) are resolved by eliminating the coincidental elements and re-projecting the merged faces. The second algorithm, denoted 'the intersection method,' is applicable to any well- formed shape, including curved-surfaced ones. It reduces the dimensionality by intersecting the polygonal trace of the shape surface at the plane of intersection, which is tested for containing the trace of the point in the plane, directly establishing the overall 3D containment relationship. A particular O(n) implementation of the 2D point-in-polygon inclusion algorithm, which is used for solving the problem once reduced in dimensionality, is also presented. The presentation is complemented by discussions of the problems associated with point-polyhedron relationship determination in general, and comparative analysis of the two particular algorithms presented
keywords	geometric modeling, point inclusion, polygons, polyhedra, computational geometry, algorithms, search, B-rep
series	CADline
email
last changed	2003/06/02 10:24

_id	e1d1
authors	Shafer, Steven A. and Kanade, Takeo
year	1982
title	Using Shadows in Finding Surface Orientations
source	61 p. : ill.` Pittsburgh, PA: Department of Computer Science, CMU, January, 1982. CMU-CS- 82-100
summary	Given a line drawing from an image with shadow regions identified, the shapes of the shadows can be used to generate constraints on the orientations of the surfaces involved. This paper describes the theory which governs those constraints under orthography. A 'Basic Shadow Problem' is first posed, in which there is a single light source, and a single surface casts a shadow on another (background) surface. There are six parameters to determine: the orientation (2 parameters) for each surface, and the direction of the vector (2 parameters) pointing at the light source. If some set of 3 of these are given in advance, the remaining 3 can then be determined geometrically
keywords	The solution method consists of identifying 'illumination surfaces' consisting of illumination vectors, assigning Huffman-Clowes line labels to
series	CADline
last changed	2003/06/02 13:58

_id	2786
authors	Woodwark, J.R.
year	1989
title	Splitting Set-Theoretic Solid Models into Connected Components
source	10 p. : ill. Winchester: IBM UK Scientific Center, IBM United Kingdom Laboratories Limited, June, 1989. IBM UKSC 210. includes bibliography In general, there is no way to tell how many pieces (connected components) a set-theoretic (CSG) solid model represents, except via conversion to a boundary model. Recent work on the elimination of redundant primitives has been linked with techniques for identifying connected components in quad-trees and oct-trees into a strategy to attack this problem. Some success has been achieved, and an experimental Prolog program, working in two dimensions, that finds connected components and determines the set-theoretic representation of each component, is reported, and further developments proposed. CSG / quadtree / octree / primitives / algorithms. 43. Woodwark, J. R. and Quinlan K. M. 'Reducing the Effect of Complexity on Volume Model Evaluation.' Computer Aided Design. April, 1982. pp. 89-95 : ill. includes bibliography.
summary	A major problem with volume modelling systems is that processing times may increase with model complexity in a worse than linear fashion. The authors have addressed this problem, for picture generation, by repeatedly dividing the space occupied by a model, and evaluating the sub-models created only when they meet a criterion of simplicity. Hidden surface elimination has been integrated with evaluation, in such a way that major portions of the model which are not visible are never evaluated. An example demonstrates a better than linear relationship between model complexity and computation time, and also shows the effect of picture complexity on the performance of the process
keywords	CAD, computational geometry, solid modeling, geometric modeling, algorithms, hidden surfaces, CSG
series	CADline
last changed	2003/06/02 13:58

_id	09f3
authors	Burt, Michael, Kent, Eli and Ne'eman, Eliyahu (et al)
year	1982
title	Single- and Multilayer Large-Span Membrane Structures for Daylight, Energy Control, and Savings
source	1982? PP. 177-183 : ill. includes bibliography
summary	This paper examines membrane-covered structures. Such structures offer many advantages and their cost of construction is lower than that of equivalent alternatives. However, these thin, single-layer membrane covers cannot provide the control of daylight and heat required to make them environmentally satisfactory and energy-efficient. To improve the performance of membrane covers, a new solution has been studied. Double-layer membranes can be built without severe technical difficulties and provide a much higher degree of static and dynamic control. Further work is being carried out to study the option of incorporating into the two layer membrane structures solar collectors between the layers, thus converting the large area of the membrane cover into an active solar system
keywords	lighting, energy, analysis, topology, structures, building
series	CADline
last changed	2003/06/02 10:24

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