Computing and Information Systems - Theses
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ItemA multistage computer model of picture scanning, image understanding, and environment analysis, guided by research into human and primate visual systems(University of Melbourne, Faculty of Engineering,, 1983)This paper describes the design and some testing of a computational model of picture scanning and image understanding (TRIPS), which outputs a description of the scene in a subset of English. This model can be extended to control the analysis of a three dimensional environment and changes of the viewing system's position within that environment. The model design is guided by a summary of neurophysiological, psychological, and psychophysical observations and theories concerning visual perception in humans and other primates, with an emphasis on eye movements. These results indicate that lower level visual information is processed in parallel in a spatial representation while higher level processing is mostly sequential, using a symbolic, post iconic, representation. The emphasis in this paper is on simulating the cognitive aspects of eye movement control and the higher level post iconic representation of images. The design incorporates several subsystems. The highest level control module is described in detail, since computer models Of eye movement which use cognitively guided saccade selection are not common. For other modules, the interfaces with the whole system and the internal computations required are out lined, as existing image processing techniques can be applied to perform these computations. Control is based on a production . system, which uses an "hypothesising" system - a simplified probabilistic associative production system - to determine which production to apply. A framework for an image analysis language (TRIAL), based on "THINGS". and "RELATIONS" is presented, with algorithms described in detail for the matching procedure and the transformations of size, orientation, position, and so On. TRIAL expressions in the productions are used to generate "cognitive expectations" concerning future eye movements and their effects which can influence the control of the system. Models of low level feature extraction, with parallel processing of iconic representations have been common in computer vision literature, as are techniques for image manipulation and syntactic and statistical analysis� Parallel and serial systems have also been extensively investigated. This model proposes an integration Of these approaches using each technique in the domain to which it is suited. The model proposed for the inferotemporal cortex could be also suitable as a model of the posterior parietal cortex. A restricted version of the picture scanning model (TRIPS) has been implemented, which demonstrates the consistency of the model and also exhibits some behavioural characteristics qualitatively similar to primate visual systems. A TRIAL language is shown to be a useful representation for the analysis and description of scenes. key words: simulation, eye movements, computer vision systems, inferotemporal, parietal, image representation, TRIPS, TRIAL.
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ItemProgram instrumentation for the detection of software anomalies( 1985)This thesis examines the automated detection of program errors through the insertion of software instruments into the source to flag anomalies at run-time. Anomalies are located using data flow analysis and pointer checking. Explicit state variables are eliminated using the address and size of an object as keys to an implicit state variable. Expressions are functionally instrumented, that is, instrumented without decomposition. Dead definitions are characterized by a new statement-based dead-on-all-paths criterion. Inefficient definition anomalies are flagged for live definitions which are dead on most paths. The handling of objects whose parts are in many states is elucidated. The utilization of reference-only states to detect parameter anomalies for certain languages is proposed. The pointer range error and the accompanying concept of ‘base’ are invented. All of these innovations are original contributions to the field. The software tool DDF was written by the author to apply the above ideas to the C programming language.
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ItemCommunications subsystem support for multimedia workstations( 1993)Multimedia is becoming the buzz word of the 1990s. Personal computers with the capability to display video, reproduce sound and present high resolution graphics are becoming affordable, if not cheap. We present a model for the next generation of these systems: the multimedia workstation. The multimedia workstation's central feature is its ability to communicate at high speed with other computers, not just multimedia workstations, in widely dispersed places. We discuss the expected capabilities of the workstation and the functionality of the networks that will make the workstation possible. Two main types of network to provide interconnection for the multimedia workstation are identified: a heterogeneous network of networks and a homogeneous telecommunications network. The cost of the multimedia workstation suggests that it cannot be designed as simply a video telephone. Instead it must be a versatile work support tool. Video conferencing will be a central facility; but a range of tools to support collaborative work are also needed. The communication requirements of these new applications are used to assess the current generation of communication subsystems. Several areas of weakness are identified. A variety of solutions to the problem areas are suggested, including new operating system paradigms, new protocols, and extensive hardware support for the higher level of communications processing. It is concluded that a combination of the solutions will be required for the multimedia workstation to fulfill its potential.