CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
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_id 66df
authors Cendes, Z.J., Minhas, F.U. and Silvester, P.P.
year 1982
title Universal Finite Element Matrices for Tetrahedra
source 45, [22] p Pittsburgh: Design Research Center, CMU, December, 1982. DRC- 18-58-82. includes bibliography.
summary Methods are described for forming finite element matrices for a wide variety of operators on tetrahedral finite elements, in a manner similar to that previously employed for line segments and triangles. This technique models the differentiation and product-embedding operators as rectangular matrices, and produces finite element matrices by replacing all required analytic operations by their finite matrix analogues. The method is illustrated by deriving the conventional matrix representation for Laplace's equation. Brief computer programs are given, which generate universal finite element matrices for use in various applications
keywords mathematics, computational geometry, finite elements, analysis
series CADline
last changed 2003/06/02 11:58

_id 89e4
authors Cendes, Z.J., Shenton, D. and H. Shahnasser
year 1982
title Adaptive Finite Element Mesh Generation Using the Delaunay Algorithm
source 3 p. : ill. Pittsburgh: Design Research Center, CMU, December, 1982
summary Includes bibliography. A two-dimensional generator is described which automatically creates optimal finite element meshes using the Delaunay triangulation algorithm. The mesh generator is adaptive in the sense that elements containing the largest normalized errors are automatically refined, providing meshes with a uniform error density. The system runs on a PERQ computer made by Three Rivers Computer Company. It is menu oriented and utilizes multiple command and display windows to create and edit the object description interactively. Mesh generation from the object data base is automatic, although it may be modified interactively by the user if desired. Application of the mesh generator to electric machine design and to magnetic bubble simulation shows it to be one of the most powerful and easy to use systems yet devised
keywords electrical engineering, triangulation, algorithms, OOPS, finite elements, analysis
series CADline
last changed 2003/06/02 11:58

_id a2fc
authors Kappel, Michael R.
year 1995
title Shading: fitting a smooth intensity surface
source Computer-Aided Design, Vol. 27 (8) (1995) pp. 595-603
summary Visual realism in computer-generated images is an important goal for many computer applications. However, a tradeoff exists between the degree of realism achieved and thetime required to generate an image. Thus efficient algorithms for generating realistic images are being actively investigated.Shading is one graphical technique for rendering more realistic images of 3D objects. However, the most widely used algorithm, Gouraud shading, suffers from the Machband effect, a perceptual phenomenon that reduces realism. Gouraud shading also handles specular reflection poorly. The next most popular algorithm, Phong shading,generally reduces Mach banding and captures specular highlights, though at great computational expense. Bishop and Weimer improved the efficiency of Phong shading, buttheir algorithm introduces approximation error and is still significantly slower than Gouraud shading.A new algorithm is proposed which takes an innovative approach to shading 3D objects. A smooth intensity surface is generated with a known surface-fitting technique,Powell-Sabin quadratic interpolation. The intensity surface is generated at a modest cost using the Cendes-Wong formulae and forward differencing. The C1 surface virtuallyeliminates Mach banding.
keywords Shading
series journal paper
last changed 2003/05/15 19:33

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