Implementing non-photorealistic rendering enhancements with real-time performance
- Authors: Winnemöller, Holger
- Date: 2002 , 2013-05-09
- Subjects: Computer animation , Computer graphics , Real-time data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4580 , http://hdl.handle.net/10962/d1003135 , Computer animation , Computer graphics , Real-time data processing
- Description: We describe quality and performance enhancements, which work in real-time, to all well-known Non-photorealistic (NPR) rendering styles for use in an interactive context. These include Comic rendering, Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic elements of the different NPR styles. We list problems that need to be solved in order to implement the various renderers. Standard solutions available in the literature are introduced and in all cases extended and optimised. In particular, we extend the lighting model of the comic renderer to include a specular component and introduce multiple inter-related but independent geometric approximations which greatly improve rendering performance. We implement two completely different solutions to random perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for 3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR style, which we call super-realistic and show how sample images can be tweened in real-time to produce an image-based six degree-of-freedom renderer performing at roughly 450 frames per second. Performance values for our other renderers all lie between 10 and over 400 frames per second on homePC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve our attempted goals of increasing the creative, expressive and communicative potential of individual NPR styles, increasing performance of most of them, adding original and interesting visual qualities, and exploring new techniques or existing ones in novel ways. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2002
- Authors: Winnemöller, Holger
- Date: 2002 , 2013-05-09
- Subjects: Computer animation , Computer graphics , Real-time data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4580 , http://hdl.handle.net/10962/d1003135 , Computer animation , Computer graphics , Real-time data processing
- Description: We describe quality and performance enhancements, which work in real-time, to all well-known Non-photorealistic (NPR) rendering styles for use in an interactive context. These include Comic rendering, Sketch rendering, Hatching and Painterly rendering, but we also attempt and justify a widening of the established definition of what is considered NPR. In the individual Chapters, we identify typical stylistic elements of the different NPR styles. We list problems that need to be solved in order to implement the various renderers. Standard solutions available in the literature are introduced and in all cases extended and optimised. In particular, we extend the lighting model of the comic renderer to include a specular component and introduce multiple inter-related but independent geometric approximations which greatly improve rendering performance. We implement two completely different solutions to random perturbation sketching, solve temporal coherence issues for coal sketching and find an unexpected use for 3D textures to implement hatch-shading. Textured brushes of painterly rendering are extended by properties such as stroke-direction and texture, motion, paint capacity, opacity and emission, making them more flexible and versatile. Brushes are also provided with a minimal amount of intelligence, so that they can help in maximising screen coverage of brushes. We furthermore devise a completely new NPR style, which we call super-realistic and show how sample images can be tweened in real-time to produce an image-based six degree-of-freedom renderer performing at roughly 450 frames per second. Performance values for our other renderers all lie between 10 and over 400 frames per second on homePC hardware, justifying our real-time claim. A large number of sample screen-shots, illustrations and animations demonstrate the visual fidelity of our rendered images. In essence, we successfully achieve our attempted goals of increasing the creative, expressive and communicative potential of individual NPR styles, increasing performance of most of them, adding original and interesting visual qualities, and exploring new techniques or existing ones in novel ways. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2002
RADGIS - an improved architecture for runtime-extensible, distributed GIS applications
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
The remote configuration of devices within home entertainment networks
- Authors: Dembovsky, Colin
- Date: 2002
- Subjects: Home entertainment systems , Home video systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4685 , http://hdl.handle.net/10962/d1007795 , Home entertainment systems , Home video systems
- Description: This thesis examines home entertainment network remote configuration solutions. It does so by inspecting four home entertainment networking solution specifications - HAVi, Jini, AV/C and UPnP. Two of these (AV/C and UPnP) are implemented partially for a system allowing a TV to configure an AudioNideo Receiver (AV/R) remotely on the network (a process known as remote configuration). The two implementations are then more closely investigated and several implementation differences in the approach between the remote configuration method of device configuration and other methods of device configuration are discerned. These different approaches are then categorised into one of two theoretical models of communication for configuring devices on home entertainment networks - the Rendering model and the Programmed model. By classifying a particular method of device configuration into one of the two models, manufacturers can quickly determine the inherent strengths and weaknesses of that method , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Authors: Dembovsky, Colin
- Date: 2002
- Subjects: Home entertainment systems , Home video systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4685 , http://hdl.handle.net/10962/d1007795 , Home entertainment systems , Home video systems
- Description: This thesis examines home entertainment network remote configuration solutions. It does so by inspecting four home entertainment networking solution specifications - HAVi, Jini, AV/C and UPnP. Two of these (AV/C and UPnP) are implemented partially for a system allowing a TV to configure an AudioNideo Receiver (AV/R) remotely on the network (a process known as remote configuration). The two implementations are then more closely investigated and several implementation differences in the approach between the remote configuration method of device configuration and other methods of device configuration are discerned. These different approaches are then categorised into one of two theoretical models of communication for configuring devices on home entertainment networks - the Rendering model and the Programmed model. By classifying a particular method of device configuration into one of the two models, manufacturers can quickly determine the inherent strengths and weaknesses of that method , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
Bandwidth management and monitoring for IP network traffic : an investigation
- Authors: Irwin, Barry Vivian William
- Date: 2001
- Subjects: TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4624 , http://hdl.handle.net/10962/d1006492 , TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Description: Bandwidth management is a topic which is often discussed, but on which relatively little work has been done with regard to compiling a comprehensive set of techniques and methods for managing traffic on a network. What work has been done has concentrated on higher end networks, rather than the low bandwidth links which are commonly available in South Africa and other areas outside the United States. With more organisations increasingly making use of the Internet on a daily basis, the demand for bandwidth is outstripping the ability of providers to upgrade their infrastructure. This resource is therefore in need of management. In addition, for Internet access to become economically viable for widespread use by schools, NGOs and other academic institutions, the associated costs need to be controlled. Bandwidth management not only impacts on direct cost control, but encompasses the process of engineering a network and network resources in order to ensure the provision of as optimal a service as possible. Included in this is the provision of user education. Software has been developed for the implementation of traffic quotas, dynamic firewalling and visualisation. The research investigates various methods for monitoring and management of IP traffic with particular applicability to low bandwidth links. Several forms of visualisation for the analysis of historical and near-realtime traffic data are also discussed, including the use of three-dimensional landscapes. A number of bandwidth management practices are proposed, and the advantages of their combination, and complementary use are highlighted. By implementing these suggested policies, a holistic approach can be taken to the issue of bandwidth management on Internet links.
- Full Text:
- Date Issued: 2001
- Authors: Irwin, Barry Vivian William
- Date: 2001
- Subjects: TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4624 , http://hdl.handle.net/10962/d1006492 , TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Description: Bandwidth management is a topic which is often discussed, but on which relatively little work has been done with regard to compiling a comprehensive set of techniques and methods for managing traffic on a network. What work has been done has concentrated on higher end networks, rather than the low bandwidth links which are commonly available in South Africa and other areas outside the United States. With more organisations increasingly making use of the Internet on a daily basis, the demand for bandwidth is outstripping the ability of providers to upgrade their infrastructure. This resource is therefore in need of management. In addition, for Internet access to become economically viable for widespread use by schools, NGOs and other academic institutions, the associated costs need to be controlled. Bandwidth management not only impacts on direct cost control, but encompasses the process of engineering a network and network resources in order to ensure the provision of as optimal a service as possible. Included in this is the provision of user education. Software has been developed for the implementation of traffic quotas, dynamic firewalling and visualisation. The research investigates various methods for monitoring and management of IP traffic with particular applicability to low bandwidth links. Several forms of visualisation for the analysis of historical and near-realtime traffic data are also discussed, including the use of three-dimensional landscapes. A number of bandwidth management practices are proposed, and the advantages of their combination, and complementary use are highlighted. By implementing these suggested policies, a holistic approach can be taken to the issue of bandwidth management on Internet links.
- Full Text:
- Date Issued: 2001
An investigation into tools and protocols for commercial audio web-site creation
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
- Authors: Ndinga, S'busiso Simon
- Date: 2000
- Subjects: Web sites -- Design , Digital libraries , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4621 , http://hdl.handle.net/10962/d1006488 , Web sites -- Design , Digital libraries , Internet -- Security measures
- Description: This thesis presents a feasibility study of a Web-based digital music library and purchasing system. It investigates the current status of the enabling technologies for developing such a system. An analysis of various Internet audio codecs, streaming audio protocols, Internet credit card payment security methods, and ways for accessing remote Web databases is presented. The objective of the analysis is to determine the viability and the economic benefits of using these technologies when developing systems that facilitate music distribution over the Internet. A prototype of a distributed digital music library and purchasing system named WAPS (for Web-based Audio Purchasing System) was developed and implemented in the Java programming language. In this thesis both the physical and the logical component elements of WAPS are explored in depth so as to provide an insight into the inherent problems of creating such a system, as well as the overriding benefits derived from the creation of such a system.
- Full Text:
- Date Issued: 2000
Designing and implementing a virtual reality interaction framework
- Authors: Rorke, Michael
- Date: 2000
- Subjects: Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4623 , http://hdl.handle.net/10962/d1006491 , Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Description: Virtual Reality offers the possibility for humans to interact in a more natural way with the computer and its applications. Currently, Virtual Reality is used mainly in the field of visualisation where 3D graphics allow users to more easily view complex sets of data or structures. The field of interaction in Virtual Reality has been largely neglected due mainly to problems with input devices and equipment costs. Recent research has aimed to overcome these interaction problems, thereby creating a usable interaction platform for Virtual Reality. This thesis presents a background into the field of interaction in Virtual Reality. It goes on to propose a generic framework for the implementation of common interaction techniques into a homogeneous application development environment. This framework adds a new layer to the standard Virtual Reality toolkit – the interaction abstraction layer, or interactor layer. This separation is in line with current HCI practices. The interactor layer is further divided into specific sections – input component, interaction component, system component, intermediaries, entities and widgets. Each of these performs a specific function, with clearly defined interfaces between the different components to promote easy objectoriented implementation of the framework. The validity of the framework is shown in comparison with accepted taxonomies in the area of Virtual Reality interaction. Thus demonstrating that the framework covers all the relevant factors involved in the field. Furthermore, the thesis describes an implementation of this framework. The implementation was completed using the Rhodes University CoRgi Virtual Reality toolkit. Several postgraduate students in the Rhodes University Computer Science Department utilised the framework implementation to develop a set of case studies. These case studies demonstrate the practical use of the framework to create useful Virtual Reality applications, as well as demonstrating the generic nature of the framework and its extensibility to be able to handle new interaction techniques. Finally, the generic nature of the framework is further demonstrated by moving it from the standard CoRgi Virtual Reality toolkit, to a distributed version of this toolkit. The distributed implementation of the framework utilises the Common Object Request Broker Architecture (CORBA) to implement the distribution of the objects in the system. Using this distributed implementation, we are able to ascertain that CORBA is useful in the field of distributed real-time Virtual Reality, even taking into account the extra overhead introduced by the additional abstraction layer. We conclude from this thesis that it is important to abstract the interaction layer from the other layers of a Virtual Reality toolkit in order to provide a consistent interface to developers. We have shown that our framework is implementable and useful in the field, making it easier for developers to include interaction in their Virtual Reality applications. Our framework is able to handle all the current aspects of interaction in Virtual Reality, as well as being general enough to implement future interaction techniques. The framework is also applicable to different Virtual Reality toolkits and development platforms, making it ideal for developing general, cross-platform interactive Virtual Reality applications.
- Full Text:
- Date Issued: 2000
- Authors: Rorke, Michael
- Date: 2000
- Subjects: Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4623 , http://hdl.handle.net/10962/d1006491 , Virtual reality , Computer simulation , Human-computer interaction , Computer graphics
- Description: Virtual Reality offers the possibility for humans to interact in a more natural way with the computer and its applications. Currently, Virtual Reality is used mainly in the field of visualisation where 3D graphics allow users to more easily view complex sets of data or structures. The field of interaction in Virtual Reality has been largely neglected due mainly to problems with input devices and equipment costs. Recent research has aimed to overcome these interaction problems, thereby creating a usable interaction platform for Virtual Reality. This thesis presents a background into the field of interaction in Virtual Reality. It goes on to propose a generic framework for the implementation of common interaction techniques into a homogeneous application development environment. This framework adds a new layer to the standard Virtual Reality toolkit – the interaction abstraction layer, or interactor layer. This separation is in line with current HCI practices. The interactor layer is further divided into specific sections – input component, interaction component, system component, intermediaries, entities and widgets. Each of these performs a specific function, with clearly defined interfaces between the different components to promote easy objectoriented implementation of the framework. The validity of the framework is shown in comparison with accepted taxonomies in the area of Virtual Reality interaction. Thus demonstrating that the framework covers all the relevant factors involved in the field. Furthermore, the thesis describes an implementation of this framework. The implementation was completed using the Rhodes University CoRgi Virtual Reality toolkit. Several postgraduate students in the Rhodes University Computer Science Department utilised the framework implementation to develop a set of case studies. These case studies demonstrate the practical use of the framework to create useful Virtual Reality applications, as well as demonstrating the generic nature of the framework and its extensibility to be able to handle new interaction techniques. Finally, the generic nature of the framework is further demonstrated by moving it from the standard CoRgi Virtual Reality toolkit, to a distributed version of this toolkit. The distributed implementation of the framework utilises the Common Object Request Broker Architecture (CORBA) to implement the distribution of the objects in the system. Using this distributed implementation, we are able to ascertain that CORBA is useful in the field of distributed real-time Virtual Reality, even taking into account the extra overhead introduced by the additional abstraction layer. We conclude from this thesis that it is important to abstract the interaction layer from the other layers of a Virtual Reality toolkit in order to provide a consistent interface to developers. We have shown that our framework is implementable and useful in the field, making it easier for developers to include interaction in their Virtual Reality applications. Our framework is able to handle all the current aspects of interaction in Virtual Reality, as well as being general enough to implement future interaction techniques. The framework is also applicable to different Virtual Reality toolkits and development platforms, making it ideal for developing general, cross-platform interactive Virtual Reality applications.
- Full Text:
- Date Issued: 2000
Development of the components of a low cost, distributed facial virtual conferencing system
- Authors: Panagou, Soterios
- Date: 2000 , 2011-11-10
- Subjects: Virtual computer systems , Virtual reality , Computer conferencing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4622 , http://hdl.handle.net/10962/d1006490 , Virtual computer systems , Virtual reality , Computer conferencing
- Description: This thesis investigates the development of a low cost, component based facial virtual conferencing system. The design is decomposed into an encoding phase and a decoding phase, which communicate with each other via a network connection. The encoding phase is composed of three components: model acquisition (which handles avatar generation), pose estimation and expression analysis. Audio is not considered part of the encoding and decoding process, and as such is not evaluated. The model acquisition component is implemented using a visual hull reconstruction algorithm that is able to reconstruct real-world objects using only sets of images of the object as input. The object to be reconstructed is assumed to lie in a bounding volume of voxels. The reconstruction process involves the following stages: - Space carving for basic shape extraction; - Isosurface extraction to remove voxels not part of the surface of the reconstruction; - Mesh connection to generate a closed, connected polyhedral mesh; - Texture generation. Texturing is achieved by Gouraud shading the reconstruction with a vertex colour map; - Mesh decimation to simplify the object. The original algorithm has complexity O(n), but suffers from an inability to reconstruct concave surfaces that do not form part of the visual hull of the object. A novel extension to this algorithm based on Normalised Cross Correlation (NCC) is proposed to overcome this problem. An extension to speed up traditional NCC evaluations is proposed which reduces the NCC search space from a 2D search problem down to a single evaluation. Pose estimation and expression analysis are performed by tracking six fiducial points on the face of a subject. A tracking algorithm is developed that uses Normalised Cross Correlation to facilitate robust tracking that is invariant to changing lighting conditions, rotations and scaling. Pose estimation involves the recovery of the head position and orientation through the tracking of the triangle formed by the subject's eyebrows and nose tip. A rule-based evaluation of points that are tracked around the subject's mouth forms the basis of the expression analysis. A user assisted feedback loop and caching mechanism is used to overcome tracking errors due to fast motion or occlusions. The NCC tracker is shown to achieve a tracking performance of 10 fps when tracking the six fiducial points. The decoding phase is divided into 3 tasks, namely: avatar movement, expression generation and expression management. Avatar movement is implemented using the base VR system. Expression generation is facilitated using a Vertex Interpolation Deformation method. A weighting system is proposed for expression management. Its function is to gradually transform from one expression to the next. The use of the vertex interpolation method allows real-time deformations of the avatar representation, achieving 16 fps when applied to a model consisting of 7500 vertices. An Expression Parameter Lookup Table (EPLT) facilitates an independent mapping between the two phases. It defines a list of generic expressions that are known to the system and associates an Expression ID with each one. For each generic expression, it relates the expression analysis rules for any subject with the expression generation parameters for any avatar model. The result is that facial expression replication between any subject and avatar combination can be performed by transferring only the Expression ID from the encoder application to the decoder application. The ideas developed in the thesis are demonstrated in an implementation using the CoRgi Virtual Reality system. It is shown that the virtual-conferencing application based on this design requires only a bandwidth of 2 Kbps. , Adobe Acrobat Pro 9.4.6 , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 2000
- Authors: Panagou, Soterios
- Date: 2000 , 2011-11-10
- Subjects: Virtual computer systems , Virtual reality , Computer conferencing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4622 , http://hdl.handle.net/10962/d1006490 , Virtual computer systems , Virtual reality , Computer conferencing
- Description: This thesis investigates the development of a low cost, component based facial virtual conferencing system. The design is decomposed into an encoding phase and a decoding phase, which communicate with each other via a network connection. The encoding phase is composed of three components: model acquisition (which handles avatar generation), pose estimation and expression analysis. Audio is not considered part of the encoding and decoding process, and as such is not evaluated. The model acquisition component is implemented using a visual hull reconstruction algorithm that is able to reconstruct real-world objects using only sets of images of the object as input. The object to be reconstructed is assumed to lie in a bounding volume of voxels. The reconstruction process involves the following stages: - Space carving for basic shape extraction; - Isosurface extraction to remove voxels not part of the surface of the reconstruction; - Mesh connection to generate a closed, connected polyhedral mesh; - Texture generation. Texturing is achieved by Gouraud shading the reconstruction with a vertex colour map; - Mesh decimation to simplify the object. The original algorithm has complexity O(n), but suffers from an inability to reconstruct concave surfaces that do not form part of the visual hull of the object. A novel extension to this algorithm based on Normalised Cross Correlation (NCC) is proposed to overcome this problem. An extension to speed up traditional NCC evaluations is proposed which reduces the NCC search space from a 2D search problem down to a single evaluation. Pose estimation and expression analysis are performed by tracking six fiducial points on the face of a subject. A tracking algorithm is developed that uses Normalised Cross Correlation to facilitate robust tracking that is invariant to changing lighting conditions, rotations and scaling. Pose estimation involves the recovery of the head position and orientation through the tracking of the triangle formed by the subject's eyebrows and nose tip. A rule-based evaluation of points that are tracked around the subject's mouth forms the basis of the expression analysis. A user assisted feedback loop and caching mechanism is used to overcome tracking errors due to fast motion or occlusions. The NCC tracker is shown to achieve a tracking performance of 10 fps when tracking the six fiducial points. The decoding phase is divided into 3 tasks, namely: avatar movement, expression generation and expression management. Avatar movement is implemented using the base VR system. Expression generation is facilitated using a Vertex Interpolation Deformation method. A weighting system is proposed for expression management. Its function is to gradually transform from one expression to the next. The use of the vertex interpolation method allows real-time deformations of the avatar representation, achieving 16 fps when applied to a model consisting of 7500 vertices. An Expression Parameter Lookup Table (EPLT) facilitates an independent mapping between the two phases. It defines a list of generic expressions that are known to the system and associates an Expression ID with each one. For each generic expression, it relates the expression analysis rules for any subject with the expression generation parameters for any avatar model. The result is that facial expression replication between any subject and avatar combination can be performed by transferring only the Expression ID from the encoder application to the decoder application. The ideas developed in the thesis are demonstrated in an implementation using the CoRgi Virtual Reality system. It is shown that the virtual-conferencing application based on this design requires only a bandwidth of 2 Kbps. , Adobe Acrobat Pro 9.4.6 , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 2000
Distributed authentication for resource control
- Authors: Burdis, Keith Robert
- Date: 2000
- Subjects: Computers -- Access control , Data protection , Computer networks -- Security measures , Electronic data processing departments -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4630 , http://hdl.handle.net/10962/d1006512 , Computers -- Access control , Data protection , Computer networks -- Security measures , Electronic data processing departments -- Security measures
- Description: This thesis examines distributed authentication in the process of controlling computing resources. We investigate user sign-on and two of the main authentication technologies that can be used to control a resource through authentication and providing additional security services. The problems with the existing sign-on scenario are that users have too much credential information to manage and are prompted for this information too often. Single Sign-On (SSO) is a viable solution to this problem if physical procedures are introduced to minimise the risks associated with its use. The Generic Security Services API (GSS-API) provides security services in a manner in- dependent of the environment in which these security services are used, encapsulating security functionality and insulating users from changes in security technology. The un- derlying security functionality is provided by GSS-API mechanisms. We developed the Secure Remote Password GSS-API Mechanism (SRPGM) to provide a mechanism that has low infrastructure requirements, is password-based and does not require the use of long-term asymmetric keys. We provide implementations of the Java GSS-API bindings and the LIPKEY and SRPGM GSS-API mechanisms. The Secure Authentication and Security Layer (SASL) provides security to connection- based Internet protocols. After finding deficiencies in existing SASL mechanisms we de- veloped the Secure Remote Password SASL mechanism (SRP-SASL) that provides strong password-based authentication and countermeasures against known attacks, while still be- ing simple and easy to implement. We provide implementations of the Java SASL binding and several SASL mechanisms, including SRP-SASL.
- Full Text:
- Date Issued: 2000
- Authors: Burdis, Keith Robert
- Date: 2000
- Subjects: Computers -- Access control , Data protection , Computer networks -- Security measures , Electronic data processing departments -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4630 , http://hdl.handle.net/10962/d1006512 , Computers -- Access control , Data protection , Computer networks -- Security measures , Electronic data processing departments -- Security measures
- Description: This thesis examines distributed authentication in the process of controlling computing resources. We investigate user sign-on and two of the main authentication technologies that can be used to control a resource through authentication and providing additional security services. The problems with the existing sign-on scenario are that users have too much credential information to manage and are prompted for this information too often. Single Sign-On (SSO) is a viable solution to this problem if physical procedures are introduced to minimise the risks associated with its use. The Generic Security Services API (GSS-API) provides security services in a manner in- dependent of the environment in which these security services are used, encapsulating security functionality and insulating users from changes in security technology. The un- derlying security functionality is provided by GSS-API mechanisms. We developed the Secure Remote Password GSS-API Mechanism (SRPGM) to provide a mechanism that has low infrastructure requirements, is password-based and does not require the use of long-term asymmetric keys. We provide implementations of the Java GSS-API bindings and the LIPKEY and SRPGM GSS-API mechanisms. The Secure Authentication and Security Layer (SASL) provides security to connection- based Internet protocols. After finding deficiencies in existing SASL mechanisms we de- veloped the Secure Remote Password SASL mechanism (SRP-SASL) that provides strong password-based authentication and countermeasures against known attacks, while still be- ing simple and easy to implement. We provide implementations of the Java SASL binding and several SASL mechanisms, including SRP-SASL.
- Full Text:
- Date Issued: 2000
Minimal motion capture with inverse kinematics for articulated human figure animation
- Authors: Casanueva, Luis
- Date: 2000
- Subjects: Virtual reality , Image processing -- Digital techniques
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4620 , http://hdl.handle.net/10962/d1006485 , Virtual reality , Image processing -- Digital techniques
- Description: Animating an articulated figure usually requires expensive hardware in terms of motion capture equipment, processing power and rendering power. This implies a high cost system and thus eliminates the use of personal computers to drive avatars in virtual environments. We propose a system to animate an articulated human upper body in real-time, using minimal motion capture trackers to provide position and orientation for the limbs. The system has to drive an avatar in a virtual environment on a low-end computer. The cost of the motion capture equipment must be relatively low (hence the use of minimal trackers). We discuss the various types of motion capture equipment and decide to use electromagnetic trackers which are adequate for our requirements while being reasonably priced. We also discuss the use of inverse kinematics to solve for the articulated chains making up the topology of the articulated figure. Furthermore, we offer a method to describe articulated chains as well as a process to specify the reach of up to four link chains with various levels of redundancy for use in articulated figures. We then provide various types of constraints to reduce the redundancy of non-defined articulated chains, specifically for chains found in an articulated human upper body. Such methods include a way to solve for the redundancy in the orientation of the neck link, as well as three different methods to solve the redundancy of the articulated human arm. The first method involves eliminating a degree of freedom from the chain, thus reducing its redundancy. The second method calculates the elevation angle of the elbow position from the elevation angle of the hand. The third method determines the actual position of the elbow from an average of previous positions of the elbow according to the position and orientation of the hand. The previous positions of the elbow are captured during the calibration process. The redundancy of the neck is easily solved due to the small amount of redundancy in the chain. When solving the arm, the first method which should give a perfect result in theory, gives a poor result in practice due to the limitations of both the motion capture equipment and the design. The second method provides an adequate result for the position of the redundant elbow in most cases although fails in some cases. Still it benefits from a simple approach as well as very little need for calibration. The third method provides the most accurate method of the three for the position of the redundant elbow although it also fails in some cases. This method however requires a long calibration session for each user. The last two methods allow for the calibration data to be used in latter session, thus reducing considerably the calibration required. In combination with a virtual reality system, these processes allow for the real-time animation of an articulated figure to drive avatars in virtual environments or for low quality animation on a low-end computer.
- Full Text:
- Date Issued: 2000
- Authors: Casanueva, Luis
- Date: 2000
- Subjects: Virtual reality , Image processing -- Digital techniques
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4620 , http://hdl.handle.net/10962/d1006485 , Virtual reality , Image processing -- Digital techniques
- Description: Animating an articulated figure usually requires expensive hardware in terms of motion capture equipment, processing power and rendering power. This implies a high cost system and thus eliminates the use of personal computers to drive avatars in virtual environments. We propose a system to animate an articulated human upper body in real-time, using minimal motion capture trackers to provide position and orientation for the limbs. The system has to drive an avatar in a virtual environment on a low-end computer. The cost of the motion capture equipment must be relatively low (hence the use of minimal trackers). We discuss the various types of motion capture equipment and decide to use electromagnetic trackers which are adequate for our requirements while being reasonably priced. We also discuss the use of inverse kinematics to solve for the articulated chains making up the topology of the articulated figure. Furthermore, we offer a method to describe articulated chains as well as a process to specify the reach of up to four link chains with various levels of redundancy for use in articulated figures. We then provide various types of constraints to reduce the redundancy of non-defined articulated chains, specifically for chains found in an articulated human upper body. Such methods include a way to solve for the redundancy in the orientation of the neck link, as well as three different methods to solve the redundancy of the articulated human arm. The first method involves eliminating a degree of freedom from the chain, thus reducing its redundancy. The second method calculates the elevation angle of the elbow position from the elevation angle of the hand. The third method determines the actual position of the elbow from an average of previous positions of the elbow according to the position and orientation of the hand. The previous positions of the elbow are captured during the calibration process. The redundancy of the neck is easily solved due to the small amount of redundancy in the chain. When solving the arm, the first method which should give a perfect result in theory, gives a poor result in practice due to the limitations of both the motion capture equipment and the design. The second method provides an adequate result for the position of the redundant elbow in most cases although fails in some cases. Still it benefits from a simple approach as well as very little need for calibration. The third method provides the most accurate method of the three for the position of the redundant elbow although it also fails in some cases. This method however requires a long calibration session for each user. The last two methods allow for the calibration data to be used in latter session, thus reducing considerably the calibration required. In combination with a virtual reality system, these processes allow for the real-time animation of an articulated figure to drive avatars in virtual environments or for low quality animation on a low-end computer.
- Full Text:
- Date Issued: 2000
A distributed approach to surround sound production
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
- Authors: Smith, Adrian Wilfrid
- Date: 1999
- Subjects: Surround-sound systems , Computer sound processing , Music -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4602 , http://hdl.handle.net/10962/d1004855 , Surround-sound systems , Computer sound processing , Music -- Data processing
- Description: The requirement for multi-channel surround sound in audio production applications is growing rapidly. Audio processing in these applications can be costly, particularly in multi-channel systems. A distributed approach is proposed for the development of a realtime spatialization system for surround sound music production, using Ambisonic surround sound methods. The latency in the system is analyzed, with a focus on the audio processing and network delays, in order to ascertain the feasibility of an enhanced, distributed real-time spatialization system.
- Full Text:
- Date Issued: 1999
Adaptive flow management of multimedia data with a variable quality of service
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
- Authors: Littlejohn, Paul Stephen
- Date: 1999
- Subjects: Multimedia systems , Multimedia systems -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4605 , http://hdl.handle.net/10962/d1004863 , Multimedia systems , Multimedia systems -- Evaluation
- Description: Much of the current research involving the delivery of multimedia data focuses on the need to maintain a constant Quality of Service (QoS) throughout the lifetime of the connection. Delivery of a constant QoS requires that a guaranteed bandwidth is available for the entire connection. Techniques, such as resource reservation, are able to provide for this. These approaches work well across networks that are fairly homogeneous, and which have sufficient resources to sustain the guarantees, but are not currently viable over either heterogeneous or unreliable networks. To cater for the great number of networks (including the Internet) which do not conform to the ideal conditions required by constant Quality of Service mechanisms, this thesis proposes a different approach, that of dynamically adjusting the QoS in response to changing network conditions. Instead of optimizing the Quality of Service, the approach used in this thesis seeks to ensure the delivery of the information, at the best possible quality, as determined by the carrying ability of the poorest segment in the network link. To illustrate and examine this model, a service-adaptive system is described, which allows for the streaming of multimedia audio data across a network using the RealTime Transport Protocol. This application continually adjusts its service requests in response to the current network conditions. A client/server model is outlined whereby the server attempts to provide scalable media content, in this case audio data, to a client at the highest possible Quality of Service. The thesis presents and evaluates a number of renegotiation methods for adjusting the Quality of Service between the client and server. An A djusted QoS renegotiation method algorithm is suggested, which delivers the best possible quality, within an acceptable loss boundary.
- Full Text:
- Date Issued: 1999
An investigation into the use of IEEE 1394 for audio and control data distribution in music studio environments
- Authors: Laubscher, Robert Alan
- Date: 1999 , 2011-11-10
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4619 , http://hdl.handle.net/10962/d1006483 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using a new digital interconnection technology, the IEEE-1394 High Performance Serial Bus, for audio and control data distribution in local and remote music recording studio environments. Current methods for connecting studio devices are described, and the need for a new digital interconnection technology explained. It is shown how this new interconnection technology and developing protocol standards make provision for multi-channel audio and control data distribution, routing, copyright protection, and device synchronisation. Feasibility is demonstrated by the implementation of a custom hardware and software solution. Remote music studio connectivity is considered, and the emerging standards and technologies for connecting future music studio utilising this new technology are discussed. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Laubscher, Robert Alan
- Date: 1999 , 2011-11-10
- Subjects: Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4619 , http://hdl.handle.net/10962/d1006483 , Digital electronics , Sound -- Recording and reproducing -- Digital techniques , MIDI (Standard) , Music -- Data processing , Computer sound processing
- Description: This thesis investigates the feasibility of using a new digital interconnection technology, the IEEE-1394 High Performance Serial Bus, for audio and control data distribution in local and remote music recording studio environments. Current methods for connecting studio devices are described, and the need for a new digital interconnection technology explained. It is shown how this new interconnection technology and developing protocol standards make provision for multi-channel audio and control data distribution, routing, copyright protection, and device synchronisation. Feasibility is demonstrated by the implementation of a custom hardware and software solution. Remote music studio connectivity is considered, and the emerging standards and technologies for connecting future music studio utilising this new technology are discussed. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
An object-oriented toolkit for music notation
- Authors: Eales, Andrew Arnold
- Date: 1999 , 2000-04-26
- Subjects: Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4618 , http://hdl.handle.net/10962/d1006473 , Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Description: This thesis investigates the design and implementation of an object-oriented toolkit for music notation. It considers whether object-oriented technology provides features that are desirable for representing music notation. The ability to sympathetically represent the conventions of music notation provides software tools that are flexible to use, and easily extended to represent less common features of music notation. The design and implementation of an object-oriented class hierarchy that captures the structural and semantic relationships of music notation symbols is described. Functions that search for symbols, and update symbol positions are also implemented. Traditional context-sensitive and spatial relationships between music symbols may be maintained, or extended to provide notational features found in modern music. MIDI functionality includes the ability to play music notation and to allow step-recording of MIDI events. The toolkit has been designed to simplify the creation of applications that make use of music notation; example applications are created to demonstrate its capabilities. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
- Authors: Eales, Andrew Arnold
- Date: 1999 , 2000-04-26
- Subjects: Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4618 , http://hdl.handle.net/10962/d1006473 , Musical notation , Object-oriented programming (Computer science) , Computer music -- History and criticism , Musical notation -- Software
- Description: This thesis investigates the design and implementation of an object-oriented toolkit for music notation. It considers whether object-oriented technology provides features that are desirable for representing music notation. The ability to sympathetically represent the conventions of music notation provides software tools that are flexible to use, and easily extended to represent less common features of music notation. The design and implementation of an object-oriented class hierarchy that captures the structural and semantic relationships of music notation symbols is described. Functions that search for symbols, and update symbol positions are also implemented. Traditional context-sensitive and spatial relationships between music symbols may be maintained, or extended to provide notational features found in modern music. MIDI functionality includes the ability to play music notation and to allow step-recording of MIDI events. The toolkit has been designed to simplify the creation of applications that make use of music notation; example applications are created to demonstrate its capabilities. , Microsoft Word , Adobe Acrobat 9.46 Paper Capture Plug-in
- Full Text:
- Date Issued: 1999
Buffering strategies and bandwidth renegotiation for MPEG video streams
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
- Authors: Schonken, Nico
- Date: 1999
- Subjects: Video compression , Computer algorithms , Digital video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4651 , http://hdl.handle.net/10962/d1006620 , Video compression , Computer algorithms , Digital video
- Description: This paper confirms the existence of short-term and long-term variation of the required bandwidth for MPEG videostreams. We show how the use of a small amount of buffering and GOP grouping can significantly reduce the effect of the short-term variation. By introducing a number of bandwidth renegotiation techniques, which can be applied to MPEG video streams in general, we are able to reduce the effect of long-term variation. These techniques include those that need the a priori knowledge of frame sizes as well as one that can renegotiate dynamically. A costing algorithm has also been introduced in order to compare various proposals against each other.
- Full Text:
- Date Issued: 1999
A framework for interpreting noisy, two-dimensional images, based on a fuzzification of programmed, attributed graph grammars
- Authors: Watkins, Gregory Shroll
- Date: 1998
- Subjects: Music -- Data processing Computer sound processing Artificial intelligence -- Musical applications Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4604 , http://hdl.handle.net/10962/d1004862
- Description: This thesis investigates a fuzzy syntactic approach to the interpretation of noisy two-dimensional images. This approach is based on a modification of the attributed graph grammar formalism to utilise fuzzy membership functions in the applicability predicates. As far as we are aware, this represents the first such modification of graph grammars. Furthermore, we develop a method for programming the resultant fuzzy attributed graph grammars through the use of non-deterministic control diagrams. To do this, we modify the standard programming mechanism to allow it to cope with the fuzzy certainty values associated with productions in our grammar. Our objective was to develop a flexible framework which can be used for the recognition of a wide variety of image classes, and which is adept at dealing with noise in these images. Programmed graph grammars are specifically chosen for the ease with which they allow one to specify a new two-dimensional image class. We implement a prototype system for Optical Music Recognition using our framework. This system allows us to test the capabilities of the framework for coping with noise in the context of handwritten music score recognition. Preliminary results from the prototype system show that the framework copes well with noisy images.
- Full Text:
- Date Issued: 1998
- Authors: Watkins, Gregory Shroll
- Date: 1998
- Subjects: Music -- Data processing Computer sound processing Artificial intelligence -- Musical applications Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4604 , http://hdl.handle.net/10962/d1004862
- Description: This thesis investigates a fuzzy syntactic approach to the interpretation of noisy two-dimensional images. This approach is based on a modification of the attributed graph grammar formalism to utilise fuzzy membership functions in the applicability predicates. As far as we are aware, this represents the first such modification of graph grammars. Furthermore, we develop a method for programming the resultant fuzzy attributed graph grammars through the use of non-deterministic control diagrams. To do this, we modify the standard programming mechanism to allow it to cope with the fuzzy certainty values associated with productions in our grammar. Our objective was to develop a flexible framework which can be used for the recognition of a wide variety of image classes, and which is adept at dealing with noise in these images. Programmed graph grammars are specifically chosen for the ease with which they allow one to specify a new two-dimensional image class. We implement a prototype system for Optical Music Recognition using our framework. This system allows us to test the capabilities of the framework for coping with noise in the context of handwritten music score recognition. Preliminary results from the prototype system show that the framework copes well with noisy images.
- Full Text:
- Date Issued: 1998
An investigation of nondeterminism in functional programming languages
- Authors: Graham, Gwyneth Clare
- Date: 1997
- Subjects: Functional programming languages
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4658 , http://hdl.handle.net/10962/d1006658 , Functional programming languages
- Description: This thesis investigates nondeterminism in functional programming languages. To establish a precise understanding of nondeterministic language properties, Sondergaard and Sestoft's analysis and definitions of functional language properties are adopted as are the characterizations of weak and strong nondeterminism. This groundwork is followed by a denotational semantic description of a nondeterministic language (suggested by Sondergaard and Sestoft). In this manner, a precise characterization of the effects of strong nondeterminism is developed. Methods used to hide nondeterminism to in order to overcome or sidestep the problem of strong nondeterminism in pure functional languages are defined. These different techniques ensure that functional languages remain pure but also include some of the advantages of nondeterminism. Lastly, this discussion of nondeterminism is applied to the area of functional parallel language implementation to indicate that the related problem and the possible solutions are not purely academic. This application gives rise to an interesting discussion on optimization of list parallelism. This technique relies on the ability to decide when a bag may be used instead of a list.
- Full Text:
- Date Issued: 1997
- Authors: Graham, Gwyneth Clare
- Date: 1997
- Subjects: Functional programming languages
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4658 , http://hdl.handle.net/10962/d1006658 , Functional programming languages
- Description: This thesis investigates nondeterminism in functional programming languages. To establish a precise understanding of nondeterministic language properties, Sondergaard and Sestoft's analysis and definitions of functional language properties are adopted as are the characterizations of weak and strong nondeterminism. This groundwork is followed by a denotational semantic description of a nondeterministic language (suggested by Sondergaard and Sestoft). In this manner, a precise characterization of the effects of strong nondeterminism is developed. Methods used to hide nondeterminism to in order to overcome or sidestep the problem of strong nondeterminism in pure functional languages are defined. These different techniques ensure that functional languages remain pure but also include some of the advantages of nondeterminism. Lastly, this discussion of nondeterminism is applied to the area of functional parallel language implementation to indicate that the related problem and the possible solutions are not purely academic. This application gives rise to an interesting discussion on optimization of list parallelism. This technique relies on the ability to decide when a bag may be used instead of a list.
- Full Text:
- Date Issued: 1997
Grouping complex systems for classification and parallel simulation
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
Modelling parallel and distributed virtual reality systems for performance analysis and comparison
- Authors: Bangay, Shaun Douglas
- Date: 1997
- Subjects: Virtual reality Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4657 , http://hdl.handle.net/10962/d1006656
- Description: Most Virtual Reality systems employ some form of parallel processing, making use of multiple processors which are often distributed over large areas geographically, and which communicate via various forms of message passing. The approaches to parallel decomposition differ for each system, as do the performance implications of each approach. Previous comparisons have only identified and categorized the different approaches. None have examined the performance issues involved in the different parallel decompositions. Performance measurement for a Virtual Reality system differs from that of other parallel systems in that some measure of the delays involved with the interaction of the separate components is required, in addition to the measure of the throughput of the system. Existing performance analysis approaches are typically not well suited to providing both these measures. This thesis describes the development of a performance analysis technique that is able to provide measures of both interaction latency and cycle time for a model of a Virtual Reality system. This technique allows performance measures to be generated as symbolic expressions describing the relationships between the delays in the model. It automatically generates constraint regions, specifying the values of the system parameters for which performance characteristics change. The performance analysis technique shows strong agreement with values measured from implementation of three common decomposition strategies on two message passing architectures. The technique is successfully applied to a range of parallel decomposition strategies found in Parallel and Distributed Virtual Reality systems. For each system, the primary decomposition techniques are isolated and analysed to determine their performance characteristics. This analysis allows a comparison of the various decomposition techniques, and in many cases reveals trends in their behaviour that would have gone unnoticed with alternative analysis techniques. The work described in this thesis supports the Performance Analysis and Comparison of Parallel and Distributed Virtual Reality systems. In addition it acts as a reference, describing the performance characteristics of decomposition strategies used in Virtual Reality systems.
- Full Text:
- Date Issued: 1997
- Authors: Bangay, Shaun Douglas
- Date: 1997
- Subjects: Virtual reality Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4657 , http://hdl.handle.net/10962/d1006656
- Description: Most Virtual Reality systems employ some form of parallel processing, making use of multiple processors which are often distributed over large areas geographically, and which communicate via various forms of message passing. The approaches to parallel decomposition differ for each system, as do the performance implications of each approach. Previous comparisons have only identified and categorized the different approaches. None have examined the performance issues involved in the different parallel decompositions. Performance measurement for a Virtual Reality system differs from that of other parallel systems in that some measure of the delays involved with the interaction of the separate components is required, in addition to the measure of the throughput of the system. Existing performance analysis approaches are typically not well suited to providing both these measures. This thesis describes the development of a performance analysis technique that is able to provide measures of both interaction latency and cycle time for a model of a Virtual Reality system. This technique allows performance measures to be generated as symbolic expressions describing the relationships between the delays in the model. It automatically generates constraint regions, specifying the values of the system parameters for which performance characteristics change. The performance analysis technique shows strong agreement with values measured from implementation of three common decomposition strategies on two message passing architectures. The technique is successfully applied to a range of parallel decomposition strategies found in Parallel and Distributed Virtual Reality systems. For each system, the primary decomposition techniques are isolated and analysed to determine their performance characteristics. This analysis allows a comparison of the various decomposition techniques, and in many cases reveals trends in their behaviour that would have gone unnoticed with alternative analysis techniques. The work described in this thesis supports the Performance Analysis and Comparison of Parallel and Distributed Virtual Reality systems. In addition it acts as a reference, describing the performance characteristics of decomposition strategies used in Virtual Reality systems.
- Full Text:
- Date Issued: 1997
A networking approach to sharing music studio resources
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
An investigation into some critical computer networking parameters : Internet addressing and routing
- Authors: Isted, Edwin David
- Date: 1996
- Subjects: Computer networks , Internet , Electronic mail systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4608 , http://hdl.handle.net/10962/d1004874 , Computer networks , Internet , Electronic mail systems
- Description: This thesis describes the evaluation of several proposals suggested as replacements for the currenT Internet's TCPJIP protocol suite. The emphasis of this thesis is on how the proposals solve the current routing and addressing problems associated with the Internet. The addressing problem is found to be related to address space depletion, and the routing problem related to excessive routing costs. The evaluation is performed based on criteria selected for their applicability as future Internet design criteria. AIl the protocols are evaluated using the above-mentioned criteria. It is concluded that the most suitable addressing mechanism is an expandable multi-level format, with a logical separation of location and host identification information. Similarly, the most suitable network representation technique is found to be an unrestricted hierarchical structure which uses a suitable abstraction mechanism. It is further found that these two solutions could adequately solve the existing addressing and routing problems and allow substantial growth of the Internet.
- Full Text:
- Date Issued: 1996
An investigation into some critical computer networking parameters : Internet addressing and routing
- Authors: Isted, Edwin David
- Date: 1996
- Subjects: Computer networks , Internet , Electronic mail systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4608 , http://hdl.handle.net/10962/d1004874 , Computer networks , Internet , Electronic mail systems
- Description: This thesis describes the evaluation of several proposals suggested as replacements for the currenT Internet's TCPJIP protocol suite. The emphasis of this thesis is on how the proposals solve the current routing and addressing problems associated with the Internet. The addressing problem is found to be related to address space depletion, and the routing problem related to excessive routing costs. The evaluation is performed based on criteria selected for their applicability as future Internet design criteria. AIl the protocols are evaluated using the above-mentioned criteria. It is concluded that the most suitable addressing mechanism is an expandable multi-level format, with a logical separation of location and host identification information. Similarly, the most suitable network representation technique is found to be an unrestricted hierarchical structure which uses a suitable abstraction mechanism. It is further found that these two solutions could adequately solve the existing addressing and routing problems and allow substantial growth of the Internet.
- Full Text:
- Date Issued: 1996