In the parametric feature based design paradigm, most features possess arguments that are subsets of the boundary of the current model, subsets defined interactively by user selection of boundary entities. Any system for feature-based data exchange (FBDE) must support the exchange of such selections. In this paper we describe in detail an algorithm for supporting onedimensional selections (sets of edges and curves) for FBDE. The algorithm is applicable to a wide class of FBDE architectures, including the Universal Product Representation (UPR) and the STEP parametrics specification.

Path planning is a crucial step in automatic programming of coordinate measuring machines(CMMs). The goal is to generate an efficient and collision-free path for the CMM to inspect a collection of points. Previous research concentrates on path planning between two points, or sequencing the points without regard to obstacles and collisions. In this paper we propose a practical path planner that considers both sequencing and collision avoidance. The main idea is to create a roadmap of free-space, where the measurement points are nodes in the network. Once all the measurement points are in a single connected component of the roadmap, then a tour of the points is found by solving the appropriate traveling salesperson problem. CMM heuristics are used to construct the roadmap in an efficient and robust manner. The planner has been implemented and tested on real-world mechanical parts.

Analyzing the accessibility of an object's surface to probes or tools is important for many planning and programming tasks that involve spatial reasoning and arise in robotics and automation. The paper presents novel and efficient algorithms for computing accessible directions for tactile probes used in 3D digitization with Coordinate Measuring Machines. The algorithms are executed in standard computer graphics hardware. They are a nonobvious application of rendering hardware to scientific and technological areas beyond computer graphics.

Computer-controlled dimensional inspection is typically performed with coordinate measuring machines (CMMs), which are very precise Cartesian robots that use touch probes to measure the coordinates of points on a workpiece's surfaces. Automatic planning and programming of inspection tasks with a CMM involve spatial reasoning, to determine how to orient the part on the CMM, which probes to use, how to orient the probes, and so on. This paper introduces the notions of accessibility and approachability, which are important for inspection planning, and describes two sets of implemented algorithms for computing accessibility information. One of these sets of algorithms performs exact computations on polyhedral objects and is relatively slow, whereas the other uses discrete approximations and achieves high speed by exploiting standard computer graphics hardware. The discretized algorithm has been tested on real-world parts, and is sufficiently fast for industrial applications.

Interactive modeling of 3-D solids is an important and difficult problem in computer graphics. The Constructive Solid Geometry (CSG) modeling scheme is highly attractive for interactive design, due to its support for hierarchical modeling and Boolean operations. Unfortunately, current algorithms for interactive display of CSG models require expensive special-purpose hardware that is not easily available. In this paper we present a method for interactive display of CSG models using standard, widely available graphics hardware. The method enables the user to interactively modify the affine transformations associated with CSG sub-objects. The application we focus upon is that of conceptual design, a stage in the design process in which rapid, interactive visualization of the model and high-level design operations are of crucial importance, while the objects are relatively simple. The method converts the CSG graph to a novel Convex Differences Aggregate(CDA) representation. The CDA utili...