4 results for Arnott, Reece

  • Towards 3D Scanning from Digital Images by Novice Users

    Arnott, Reece (2015)

    Doctoral thesis
    University of Otago

    The uptake of hobbyist 3D printers is being held back, in part, due to the barriers associated with creating a computer model to be printed. One way of creating such a computer model is to take a 3D scan of a pre-existing object using multiple digital images of the object showing the object from different points of view. This document details one way of doing this, with particular emphasis on camera calibration: the process of estimating camera parameters for the camera that took an image. In common calibration scenarios, multiple images are used where it is assumed that the internal parameters, such as zoom and focus settings, are fixed between images and the relative placement of the camera between images needs to be estimated. This is not ideal for a novice doing 3D scanning with a “point and shoot” camera where these internal parameters may not have been held fixed between images. A common coordinate system between images with a known relationship to real-world measurements is also desirable. Additionally, in some 3D scanning scenarios that use digital images, where it is expected that a trained individual will be doing the photography and internal settings can be held constant throughout the process, the images used for doing the calibration are different from those that are used to do the object capture. A technique has been developed to overcome these shortcomings. It uses a known printed sheet of paper, called the calibration sheet, that the object to be scanned sits on so that object acquisition and camera calibration can be done from the same image. Each image is processed independently with reference to the known size of the calibration sheet so the output is automatically to scale and minor camera calibration errors with one image do not propagate and affect estimates of camera calibration parameters for other images. The calibration process developed is also one that will work where large parts of the calibration sheet are obscured.

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  • A review of current firewall technologies

    Arnott, Reece (2002-08-21)

    Masters thesis
    University of Otago

    As corporations become more reliant on Internet based resources, the security of the corporation from Internet based attacks becomes more and more important. One of prime technologies that allow the corporation to have increased security between the internal network and the Internet is that of a firewall. A firewall is a filtering system that grants the firewall administrator the ability to create certain filter rules that determine what kind of traffic is allowed to cross the firewall. This paper examines the many different types of filtering that can be applied to traffic that goes through a firewall and how these have been implemented in practice. The actual filtering is only part of what a firewall must do; the firewall must also be able to report back to the firewall administrator various items of information, such as any blocked traffic. Seven different firewall products are examined to see how the different design decisions the various vendors have made affect the implementation of certain filtering functionality. This paper also examines the logging functionality of the firewalls, as this is the main reporting mechanism that the firewall administrator will use. Much of the development of firewalls has been driven by the ‘needs’ of customers as perceived by firewall developers. This has lead to some very advanced features in some areas but significant gaps in some other areas. This paper attempts to examine some of these advanced features and highlight some of the gaps that need more research and development.

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  • Informal crash-reporting system

    Moyle, Sam A; Arnott, Reece; Kardos, Julian; Williams, Richard (2000)

    Conference paper
    University of Otago

    The Land Transport Safety Authority is a body formed by the New Zealand government, having the mandate to maintain New Zealand’s state highway infrastructure. One important source of information that helps the Land Transport Safety Authority to make decisions is crash data - recording motor vehicle crashes, location, road condition and so forth. At the current time it is recognised that there is chronic under-reporting of crashes to the New Zealand Police. In an attempt to address this problem, the Land Transport Safety Authority investigated the possibility of getting information from non-legislative sources. Tow truck operators have been targeted as a likely source of crash data, given that they will likely attend a crash scene. A prototype solution was implemented by way of web-based forms for the tow truck operators to complete. The Information Engineering and Prototyping methodology has been followed, allowing the results achieved to be reproduced in the future. A major benefit of this system is that the underlying database is extensible, allows multiple concurrent users, and can be used to generate statistics - all elements required by the Land Transport Safety Authority in their project brief. The chosen data structure supports the development of data warehouses in the future, given the ability to draw information from disparate sources and present results (reports) in a pre-prepared or ad-hoc manner. Future technological developments are discussed, including the ability to incorporate GPS~information and information gathering through the use of hand-held devices.

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  • The RepRap Project—Open Source meets 3D printing

    Arnott, Reece (2008-08-01)

    Conference item
    University of Otago

    Abstract: The RepRap Project is an open source hardware and software project headed by Adrian Bowyer of the University of Bath with the goal of producing a low cost ‘rapid prototyper’ or 3D printer i.e. a machine that can produce 3D objects (including parts for itself) that is useful and available to all. One of the projects first major milestones has now been passed: a fully functional reprap has been built using parts printed by another one. This talk is about the history of the project, my involvement in it, what is currently being worked on, and the ideas and plans for future development.

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