Advanced Vision Systems Research Articles

Localized current field hyperthermia in carcinoma of the cervix: 3-D computer simulation of SAR distribution

Software was developed for the 3D simulation of SAR distribution for a 500kHz localized current field hyperthermia system to be used in patients with carcinoma of the cervix. This hyperthermia system was specifically designed for use with a modified Fletcher-Suit intracavitary applicator. It consists of software modules for data input, tetrahedral grid generation and a numerical calculation of SAR distribution using an adaptive, multilevel finite element code. The AVS (Advanced Visual System, Inc.) system was used for the visual presentation of the results. A quasi-static approach was employed for the determination of SAR distribution. Results of the performed numerical tests were presented and they showed an important, clinically relevant ability to obtain a selective power deposition. This selective power deposition depended on the applicator geometry, i.e. the distance between the components of a Fletcher-Suit applicator and their relative position and the use of different modes of excitation.

Machine vision reaches top gear

The power and simplicity of a new generation of machine vision systems have done much to overcome the automotive industry's reluctance to invest in this technology. Most vision applications in the automotive industry are for machine guidance or quality inspections. In quality control inspections, the vision system determines whether parts or sub-assemblies are acceptable or defective and then directs motion control equipment to reject or accept them. Machine guidance applications use vision systems to improve the accuracy and speed of assembly robots and automated materials handling equipment in several areas. The most advanced machine vision systems enable a robot to locate the part or sub-assembly on which it is working, regardless of rotation or scale. In most applications, machine vision provides real-time data and live feedback to guide robots as they go through programmed sequences of operations. The new generation of vision systems can be trained to look for detailed patterns and shapes that match templates for correctly made subassemblies. Powerful pattern recognition capabilities allow vision systems to find missing material, chips, scratches, dents, misplaced markings and a variety of other flaws. As well as ensuring the quality of finished parts and products, they also enable manufacturers to reduce costs by eliminating defective pieces before wasting additional material and time on them.

Trabecular bone mineral and calculated structure of human bone specimens scanned by peripheral quantitative computed tomography: relation to biomechanical properties.

The relationship of cortical bone mineral density (BMD), and geometry to bone strength has been well documented. In this study, we used peripheral quantitative computerized tomography (pQCT) to acquire trabecular BMD and high-resolution images of trabeculae from specimens to determine their relationship with biomechanical properties. Fifty-eight human cubic trabecular bone specimens, including 26 from the vertebral bodies, were scanned in water and air. Trabecular structure was quantitated using software developed with Advanced Visual Systems interfaced on a Sun/Sparc Workstation. BMD was also obtained using a whole-body computerized tomography scanner (QCT). Nondestructive testing of the specimens was performed to assess their elastic modulus. QCT and pQCT measurements of BMD of specimens in water were strongly correlated (r2 = 0.95, p < 0.0001), with a slope (0.96) statistically not significantly different from 1. Strong correlations were found between pQCT measurements of specimens in water and in air, for BMD (r2 = 0.96, p < 0.0001), and for apparent trabecular structural parameters (r2 = 0.89-0.93, p < 0.0001). Correlations were moderate between BMD and apparent trabecular structural parameters (r2 = 0.37-0.64, p < 0.0001). Precision as coefficient of variation (CV) and standardized coefficient of variation (SCV) for these measurements was < 5%. For the vertebral specimens, the correlation was higher between elastic modulus and BMD (r2 = 0.76,p < 0.0001) than between elastic modulus and apparent trabecular structural parameters (r2 = 0.58-0.72, p < 0.0001), while the addition of apparent trabecular nodes and branches to BMD in a multivariate regression model significantly increased the correlation with the elastic modulus (r2 = 0.86, p < 0.01). Thus, pQCT can comparably and reproducibly measure trabecular bone mineral in water or air, and trabecular structure can be quantitated from pQCT images. The combination of volumetric BMD with trabecular structural parameters rather than either alone improves the prediction of biomechanical properties. Such a noninvasive approach may be useful for the preclinical study of osteoporosis.

Visualizing the dynamical behavior of Wonderland

The article concentrates on the visualization of a four dimensional continuous dynamical system, the Wonderland model. This system poses some interesting analysis challenges. Its temporal evolution, for example, is characterized by slow-fast dynamics. This means that some of the system variables vary much faster than others. The velocity varies by two magnitudes and thus makes visualization difficult. Due to the underlying slow-fast dynamics, some equilibrium surfaces play an essential role in the model's analysis. We consider equilibrium surfaces on which the derivative of the fast system variable equals zero. Due to their definition, these equilibrium surfaces do not describe stream surfaces, which means that trajectories intersect and cross them. For these surfaces we cannot use visualization techniques designed for stream surfaces, which are based on the assumption that a flow starting on the surface will stay within it. Econometrics research typically uses only elementary visualization techniques such as still images, simple line drawings, and 2D projections or cross-sections of higher dimensional phase spaces. Color use is scarce. We collaborated with econometricians to apply more sophisticated visualization techniques and adaptations to the Wonderland model using standard visualization software (AVS by Advanced Visual Systems). The visualizations provided new insights into the system's slow-fast dynamics. Using a commercial rendering package (Autodesk's 3D Studio), we also turned the visualizations into high quality images for presentations.

From WIMPS to 3D: The Development of AMAZE

Large volumes of complicated data require advanced visual query systems. These advanced systems challenge the conventional user interface metaphors and require new solutions. This paper outlines the development of one such system, called AMAZE. The development of this database interface has gone through a number of stages. Limitations of the associated structured query language and textual output lead firstly to a WIMP ‘form-based’ graphical interface being developed. When the ‘form-based’ interface was found to be insufficient a 3D graphical interface was designed and built. New visual metaphors have been developed to aid the user. Three dimensional graphics are used for both query construction and result representation and the user can then view the results using a variety of displays.

Immersed boundary method for plasma simulation in complex geometries

The immersed boundary method is a powerful tool for plasma simulation in complex geometries. A brief description of the method is provided and results from a paradigmatic simulation are reported. An advanced color graphics interface, based on an advanced visual system (AVS), is used to highlight the relevant aspects of the simulation.

Biomolecular visualization using AVS

Dataflow systems for scientific visualization are becoming increasingly sophisticated in their architecture and functionality. 2–6 AVS, from Advanced Visual Systems Inc., is a powerful dataflow environment that has been applied to many computation and visualization tasks. 2,7–9 An important, yet complex, application area is molecular modeling and biomolecular visualization. Problems in biomolecular visualization tax the capability of dataflow systems because of the diversity of operations that are required and because many operations do not fit neatly into the dataflow paradigm. Here we describe visualization strategies and auxiliary programs developed to enhance the applicability of AVS for molecular modeling. Our visualization strategy is to use general-purpose AVS modules and a small number of chemistry-specific modules. We have developed methods to control AVS using AVS-tool, a programmable interface to the AVS Command Line Interpreter (CLI), and have also developed NAB, a C-like language for writing AVS modules that has extensions for operating on proteins and nucleic acids. This strategy provides a flexible and extensible framework for a wide variety of molecular modeling tasks.

Visual surveillance in a dynamic and uncertain world

Advanced visual surveillance systems not only need to track moving objects but also interpret their patterns of behaviour. This means that solving the information integration problem becomes very important. We use conceptual knowledge of both the scene and the visual task to provide constraints. We also control the system using dynamic attention and selective processing. Bayesian belief networks support this and allow us to model dynamic dependencies between parameters involved in visual interpretation. We illustrate these arguments using experimental results from a traffic surveillance application. In particular, we demonstrate that using expectations of object trajectory, size and speed for the particular scene improves robustness and sensitivity in dynamic tracking and segmentation. We also demonstrate behavioral evaluation under attentional control using a combination of a static BBN TASKNET and dynamic network. The causal structure of these networks provides a framework for the design and integration of advanced vision systems.

High speed cutting of patterned shapes from fabrics

The machine concepts emerging for high speed cutting of patterned materials will have a fundamental effect on the way engineers approach future machine design configurations. The positive marketing advantage of such machines will rely heavily on the use of advanced machine vision systems integrated with low force cutting agents such as lasers. The high speed cutting process for lace fabric is chosen as a specific example of this research and illustrates the benefits of an integrated approach on the formulation and realisation of an advanced production machine concept. With this intelligent cutting concept flexible, variable geometry patterned materials can be cut at feed velocities in excess of 1 m/s with an accuracy of 0.3 mm.

On surface orientation detection in 3-D

Theoretical foundations of an advanced vision system capable of detecting the three-dimensional orientation of planar surfaces from a single view of a scene are presented. The standard 2-D picture records the light intensity of points registered at the point of observation, whereas data for the new vision system is represented by the direction and intensity of light rays originating from points on objects in a scene, and registered at the point of observation. The collection of these rays, i.e., light intensities and associated directions, is called an Ambient Light Array and is modelled by a vector function. In the new system the image of a flat surface is a sphere. An algorithm for the detection of orientation of a planar surface exhibiting the Lambertian reflectance characteristic and illuminated by a point light source is described, and the results of simulation in the presence of random noise are shown.

Advanced vision systems for computer-integrated manufacture Part II

This paper describes the application of computer vision techniques to solve a variety of industrial problems. Systems for robot guidance, quality assurance and inspection, and strain measurement are described and details of hardware and software components of each application are provided.

Advanced vision systems for computer-integrated manufacture Part I

As computer-integrated manufacturing facilities continue to grow in complexity, increasingly sophisticated computer based sensory systems will be required to carry out functions such as robot guidance, tool wear monitoring, and product inspection. This paper reviews progress in the development of advanced computer vision systems at the National Engineering Laboratory, UK and describes the design of hardware and software for two dimensional image analysis. A component recognition system for robotic applications is detailed and a novel structured light technique for three dimensional component analysis is described. Part II, which contains several case histories, will be published in the November issue.

United States Air Force Experience with Simulator Sickness, Research and Training

With the advent of complex, wide-screen visual flight simulators in the United States Air Force, there has also developed a significant problem with simulator-induced sickness. This paper reviews the history of this problem in the Air Force as it is understood at present and discusses its possible impact on training. It also reviews preliminary studies conducted on one of the most advanced visual systems developed thus far, the General Electric Visual System Component Development Program (VSCDP) as well as future Air Force plans for research on this system.

Advanced technology shines on the Rover 800 line

Manufacture of the new Rover car features advanced robotics and intelligent vision systems. Brian Rooks reports on the production facilities installed at Cowley near Oxford.