Michael Karasick

Efficient Delaunay triangulation using rational arithmetic

Many fundamental tests performed by geometric algorithms can be formulated in terms of finding the sign of a determinant. When these tests are implemented using fixed precision arithmetic such as floating point, they can produce incorrect answers; when they are implemented using arbitrary-precision arithmetic, they are expensive to compute. We present adaptive-precision algorithms for finding the signs of determinants of matrices with integer and rational elements. These algorithms were developed and tested by integrating them into the Guibas-Stolfi Delaunay triangulation algorithm. Through a combination of algorithm design and careful engineering of the implementation, the resulting program can triangulate a set of random rational points in the unit circle only four to five times slower than can a floating-point implementation of the algorithm. The algorithms, engineering process, and software tools developed are described.

The architecture of Montana: an open and extensible programming environment with an incremental C++ compiler

Montana is an open, extensible integrated programming environment for C++ that supports incremental compilation and linking, a persistent code cache called a CodeStore, and a set of programming interfaces to the CodeStore for tool writers. CodeStore serves as a central source of information for compiling, browsing, and debugging. CodeStore contains information about both the static and dynamic structure of the compiled program. This information spans files, macros, declarations, function bodies, templates and their instantiations, program fragment dependencies, linker relocation information, and debugging information.Montana allows the compilation process to be extended and modified [11]. Montana has been used as the basis of a number of tools [1,7], and is also used as the infrastructure of a production compiler, IBMs Visual Age C++ 4.0 [8].

Extension mechanisms in Montana

Montana is a new C++ programming environment being developed at IBM. Montana aims to improve the software development experience by providing rapid incremental builds, rapid complete builds, and a tightly integrated user interface driven from a single source of information. Montana uses a program representation (CodeStore) to achieve these aims, with compilation proceeding directly from the database. APIs for accessing information about programs from the CodeStore are also made available for tool builders. In this paper we focus on the extension mechanism in Montana, which enables integration of existing tools and creation of new sophisticated, tightly integrated tools.

Visualization of Three-Dimensional Delaunay Meshes

Abstract. We describe an algorithm for the rapid display of three-dimensional Delaunay meshes (or selected portions thereof) on standard raster displays, without the use of special purpose graphics hardware. The algorithm allows the display of the interior structure as well as the surface of the mesh, and furthermore does not require that the meshed domain be convex, or even connected. The algorithm computes a depth ordering on the mesh elements. This ordering can be used to display subsets of the mesh, as well as isosurfaces induced by fields represented on the mesh. Furthermore, by utilizing mesh coherence, the depth ordering can be used to view the mesh from front to back as well as back to front. An implementation of the algorithm has been incorporated in a system for designing and analyzing the performance of three-dimensional semiconductor and electronic packaging structures. The system is in regular use and the mesh-display algorithm has been used to visualize both meshes and fields computed over the meshes.

Semiconductor wafer representation for TCAD

This work describes the Semiconductor Wafer Representation (SWR) for representing and manipulating wafer state during process and device simulation. The goal of the SWR is to provide an object-oriented interface to a collection of functions designed for developing and integrating Technology CAD (TCAD) applications. By providing functions which can be common across many applications, we aim to greatly reduce tool development and integration time. Corporate, vendor, and university TCAD developers have worked together under the auspices of the CAD Framework Initiative to create an architecture and C++ programming interface for an SWR 1.0 draft standard. Here we describe this architecture and the results of creating and using a prototype implementation of the standard both to integrate existing TCAD tools and to develop simple new tools. >

Solid modeling on a massively parallel processor

Solid modeling underlies many technologies that are key to modern manufacturing. These range from com puter-aided design systems to robot simulators, from finite element analysis to integrated circuit process modeling. The accuracy, and hence the utility, of these models is often constrained by the amount of com puter time required to perform the desired operations. We present a family of algorithms for solid modeling operations using the Connection Machine, a massively parallel SIMD processor. We describe a data structure for representing solid models and algorithms that use the representation to implement efficiently a variety of solid modeling operations. We give a sketch of the al gorithm for intersecting solids and present computa tional experience using these algorithms. The data structure and algorithms are contrasted with those of serial architectures, and execution times are compared.

Schemata for interrogating solid boundaries

Data structures used by geometric modellers to construct and modify geometric objects are usually different than those needed by application programs to interrogate the geometry. For example, rendering programs typically use oriented polygons, not the combinatorial boundary information maintained by polyhedral geometric modellers. We describe a mechanism for constructing application views, or schemata, of geometric objects described by a large class of boundary representations. These views are constructed by interposing a layer of software between a geometric modeller and an application program. We call this software layer a schema library. We illustrate the utility of schemata and their libraries by discussing an implemented schema library used by a geometric editor whose underlying geometric modeller manipulates cell-complexes, i. e., polyhedral subdivisions of three-space.

Intersecting solids on a massively parallel processor

Solid modeling underlies many technologies that are key to modern manufacturing. These range from CAD systems to robot simulators, from finite-element analysis to integrated circuit process modeling. The accuracy, and hence the utility, of these models is often constrained by the amount of computer time required to perform the desired operations. In this paper we present, in detail, an efficient algorithm for parallel intersections of solids using the Connection Machine, a massively parallel SIMD processor. We describe the data structure for representing the solid models and detail the intersection algorithm, giving special attention to implementation issues. We provide performance results, comparing the parallel algorithm to a serial intersection algorithm.