Timothy S. Newman

A survey of automated visual inspection

Abstract In this paper, we survey the automated visual inspection systems and techniques that have been reported in the literature from 1988 to 1993. Several earlier systems are also discussed. In the survey, a taxonomy of inspection systems based on their sensory input is presented. The general benefits and feasibility of automated visual inspection are also discussed. We present common approaches to visual inspection and also consider the specification and analysis of dimensional tolerances and their influence on the inspection task(s). One of the recent developments in automated visual inspection, namely the expanded role of computer-aided design (CAD) data in many systems, is examined in detail.

A survey of the marching cubes algorithm

A survey of the development of the marching cubes algorithm [W. Lorensen, H. Cline, Marching cubes: a high resolution 3D surface construction algorithm. Computer Graphics 1987; 21(4):163–9], a well-known cell-by-cell method for extraction of isosurfaces from scalar volumetric data sets, is presented. The paper’s primary aim is to survey the development of the algorithm and its computational properties, extensions, and limitations (including the attempts to resolve its limitations). A rich body of publications related to this aim are included. Representative applications and spin-off work are also considered and related techniques are briefly discussed. r 2006 Elsevier Ltd. All rights reserved.

Self-Consistent Magnetosphere-Ionosphere Coupling: Theoretical Studies

[1] A theoretical examination of the electrodynamical interaction between the ionosphere and the inner magnetosphere is presented. A self-consistent ring current (RC) model has been developed that couples the electron and ion magnetospheric dynamics with the calculation of the electric field. Two new features were taken into account in order to close the self-consistent magnetosphere-ionosphere coupling loop. First, in addition to the RC ions, we have solved an electron kinetic equation in our model. Second, using the relation of Galand and Richmond [2001], we have calculated the height integrated ionospheric conductances as a function of the precipitated high energy magnetospheric electrons and ions that are produced by our model. To validate the results of our model we simulate the magnetic storm of May 2, 1986, a storm that has been comprehensively studied by Fok et al. [2001], and have compared our results with different theoretical approaches. The self-consistent inclusion of the hot electrons and their effect on the conductance results in deeper penetration of the magnetospheric electric field. In addition, a slight westward rotation of the potential pattern (compared to previous self-consistent results) is evident in the inner magnetosphere. These effects change the hot plasma distribution, especially by allowing increased access of plasma sheet ions and electrons to low L shells. These results are consistent with recent observations from the IMAGE satellite. INDEX TERMS: 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions; 7807 Space Plasma Physics: Charged particle motion and acceleration; 2753 Magnetospheric Physics: Numerical modeling; 2730 Magnetospheric Physics: Magnetosphere—inner; KEYWORDS: magnetic storms, ring current, electric fields, numerical simulations

A system for 3D CAD-based inspection using range images

Abstract An automated visual inspection system is presented for the detection of defects in range images of castings. The system uses computer-aided design (CAD) model information in several stages, including surface classification and inspection. Inspection techniques are presented for the detection of common casting defects and for the inspection of dimensional tolerances and manufacturing features. The inspection algorithms are applicable to the class of objects that contain planar and/or quadric surfaces, rather than being specialized to the visual inspection of a single object. The methods have been applied to a large number of real range images of iron castings that have real defects. The inspection system correctly classifies over 90% of the casting images.

A study of the impact of student background and preparedness on outcomes in CS I

A study that assesses the significance of student background characteristics on outcomes in a depth-first CS I course is presented. The study was conducted over a two-year period and involved more than 400 students in fourteen different course sections taught by eight different instructors in a CSAC-accredited program. In this paper, focus is on the impact of prior programming courses on CS I outcomes. In particular, the impact of the prior courses programming language and provider is reported.

Least-squares-based fitting of paraboloids

A technique for reconstructing a class of quadric surfaces from 3D data is presented. The technique is driven by a linear least-squares-based fitting mechanism. Previously, such fitting was restricted to recovery of central quadrics; here, extension of that basic mechanism to allow recovery of one commonly-occurring class of non-central quadric, the elliptic paraboloids, is described. The extension uses an indirect solution approach that involves introducing a variable to the basic mechanism that is a function of a quadric surface invariant. Results from fitting real and synthetic data are also exhibited.

On visualizing uncertainty in volumetric data: techniques and their evaluation

Abstract Four new techniques for the visualization of uncertainty in volumetric data are introduced, including three glyph-based techniques (i.e., cylinder, cone, and multi-point glyphs) and one non-glyph-based approach. The non-glyph-based approach uses an aliasing mechanism. Four of the existing techniques for visualization of uncertainty in volumetric data are also described, including transparency, color mapping, and ball and arrow glyph techniques. These new and existing techniques are analyzed via a usability study that considers four aspects of the techniques’ effectiveness (identification of the data and of the uncertainty, visual overload, and brightness contrast) for one typical volume visualization scenario. The analysis suggests that while each technique has some utility for a scenario such as the tested one, the new multi-point glyph and the existing ball and arrow glyph techniques appear to be most advantageous.

Oriented connectivity-based method for segmenting solar loops

A method based on oriented connectivity that can automatically segment arc-like structures (solar loops) from intensity images of the Suns corona is introduced. The method is a constructive approach that uses model-guided processing to enable extraction of credible loop structures. Since the solar loops are vestiges of the solar magnetic field, the model-guided processing exploits external estimates of this fields local orientations that are derived from a physical magnetic field model. Empirical studies of the methods effectiveness are also presented. The oriented connectivity-based method is the first automatic method for the segmentation of solar loops.

Approaches that exploit vector-parallelism for three rendering and volume visualization techniques

Abstract Direct volume rendering using volume ray-casting and indirect volume rendering using the Marching Cubes isosurface extraction are popular techniques for volume visualization. Surface ray-tracing is a popular graphics technique for rendering scenes composed of well-defined surface primitives. However, these techniques are relatively computationally intensive. Thus, near-real-time computational performance is a difficult goal. This paper presents approaches to these rendering and volume visualization techniques that are tuned for efficient performance on a vector-parallel supercomputer. The approaches decompose and reconstruct the techniques to exploit inherent data parallelism and the specific characteristics of the CPU. Experimental results for several datasets are also exhibited.

Efficient parallel out-of-core isosurface extraction

A new approach for large dataset isosurface extraction is presented. The approachs aim is efficient parallel isosurfacing when the dataset cannot be processed entirely in-core. The approach focuses on reducing the memory requirement and optimizing disk I/O while achieving a balanced load. In particular, an accurate model of isosurface extraction time is exploited to evenly distribute work across processors. The approach achieves processing efficiency by also avoiding unnecessary processing for portions of the dataset that are not intersected by the isosurface. To reduce the redundant computations and the storage requirements, a flexible, variably-granular data structure is utilized, thereby achieving excellent time and space performance.