Browsing by Author "Blake, Edwin H"
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- ItemOpen AccessA virtual environment authoring interface for content-expert authors(2005) Tangkuampien, Jakkaphan; Marsden, Gary; Blake, Edwin H[pg 47 missing] Since the advent of virtual reality (VR), the technology has been exploited in many areas to aid information transfer. In this respect, virtual reality can be regarded as a medium across which authors can communicate with a target group. However, many experts in non-computer-related areas, looking to exploit VR often come unstuck trying to take advantage of this medium. In these cases, one cannot blame these content-expert authors as they have successfully exploited other media prior to VR. On the other hand, the fault can not lie with the medium itself since it has been effectively exploited by other groups of authors. One probable cause could be the authoring tools themselves, or rather their interfaces to be more accurate. A tool's authoring interface is the only access point into the VR medium and one can only assume that the interfaces are not doing their job effectively. Our study was aimed at investigating authoring interfaces especially from the point of view of content-expert authors. Our approach was to involve such authors who have been able to master existing authoring tool mostly on their own. These authors were in a unique position - having managed to overcome initial difficulties, they have come to understand the inner working of the medium itself. The study was also well-suited to the appreciative inquiry (AI) methodology - a community-centric methodology that has rarely been applied in the area of computer science. Appreciative inquiry, with its root in action research, encourages a similar spiral-based methodology but with positive approach in all phases. With a group of content-expert VR authors, we applied a cycle of AI, resulting first in a list of interface issues that required some attention as well as some idea of how they can be resolved. The second phase of AI involved working closely with the authors to come up with resolution strategies to each of these issues. These solutions were then assessed for the level at which they have addressed their respective issue by another group of content-expert authors. Finally, an online survey was conducted to extend our results to the wider population of content-expert authors. The survey results confirmed that the interface issues discovered applied to the general population and that the proposed solutions were generally thought to be advantageous to the authoring process. Additionally, these positive results were encouraging since it means that our adaptation of AI was successful.
- ItemOpen AccessCOLAB: social context and user experience in collaborative multiplayer games(2017) Terblanche, Marcel; Blake, Edwin HRecent studies have shown that the social context in which people play digital multiplayer games has an effect on their experience. Whether co-players are in the same location ("co-located") or in different locations ("mediated") changes how they interact with the game and with one another. We set out to explore how these complex psychological dynamics played out in a collaborative multiplayer game, since most of the research to date has been focused on competitive gameplay scenarios. To this end, we designed a two-player puzzle-based gaming apparatus called COLAB, implementing specific features that have been proven to foster collaboration and preclude competition between players. The independent variable was player location; the dependent variable was game experience, as measured by the Social Presence in Gaming Questionnaire and the Game Experience Questionnaire, two comprehensive self-report instruments. We found a significant difference in the game experiences of players collaborating in the same location versus players collaborating in different locations. Specifically, co-located players of the collaborative game experienced significantly higher scores for negative experience than mediated players did, while mediated players experienced significantly higher levels of three key game-experience measures: positive affect, immersion, and flow.
- ItemOpen AccessA connectionist explanation of presence in virtual environments(2003) Nunez, David; Blake, Edwin HPresence has various definitions, but can be understood as the sensation that a virtual environment is a real place, that the user is actually in the virtual environment rather than at the display terminal, or that the medium used to display the environment has disappeared leaving only the environment itself. We present an attempt to unite various presence approaches by reducing each to what we believe is a common basis – the psychology of behaviour selection and control – and re-conceptualizing presence in these terms by defining cognitive presence – the mental state where the VE rather than the real environment is acting as the basis for behaviour selection. The bulk of this work represents the construction of a three-layer connectionist model to explain and predict this concept of cognitive presence. This model takes input from two major sources: the perceptual modalities of the user (bottom-up processes), and the mental state of the user (top-down processes). These two basic sources of input competitively spread activation to a central layer which competitively determines which behaviour script will be applied to regulate behaviour. We demonstrate the ability of the model to cope with current notions of presence by using it to successfully predict two published findings: one (Hendrix & Barfield, 1995) showing that presence increases with an increase in the geometric field of view of the graphical display, and another (Salln?s, 1999), which demonstrates the positive relationship between presence and the stimulation of more than one sensory modality. Apart from this theoretical analysis, we also perform two experiments to test the central tenets of our model. The first experiment aimed to show that presence is affected by both perceptual inputs (bottom-up processes), conceptual inputs (top-down processes), and the interaction of these. We collected 103 observations from a 2x2 factorial design with stimulus quality (2 levels) and conceptual priming (2 levels) as independent variables, and as dependent variable we used three measures of presence (Slater, Usoh & Steed's scale (1995), Witmer & Singer's (1998) Presence Questionnaire and our own cognitive presence measure) for the dependent variable. We found a significant main effect for stimulus quality and a significant interaction, which created a striking effect: priming the subject with material related in theme to the content of the VE increased the mean presence score for those viewing the high quality display, but decreased the mean of those viewing the low quality display. For those not primed with material related to the VE, no mean presence difference was discernible between those using high and low quality displays. The results from this study suggest that both top-down and bottom-up activation should be taken into account when explaining the causality of presence. Our second study aimed to show that presence comes about as a result not of raw sensory information, but rather due to partly-processed perceptual information. To do this we created a simple three group comparative design, with 78 observations. Each one of the three groups viewed the same VE under three display conditions: high-quality graphical, low-quality graphical, and text-only. Using the model, we predicted that the text and low-quality graphics displays would produce the same presence levels, while the high-quality display would outperform them both. The results were mixed, with the Slater, Usoh & Steed scale showing the predicted pattern, but the Presence Questionnaire showing each condition producing a significantly different presence score (in the increasing order: text, low-quality graphics, high-quality graphics). We conclude from our studies that the model shows the correct basic structure, but that it requires some refinement with regards to its dealings with non-immersive displays. We examined the performance our presence measure, which was found to not perform satisfactorily. We conclude by proposing some points relevant to the methodology of presence research, and by suggesting some avenues for future expansion of our model.
- ItemOpen AccessDAS Writeback: A collaborative annotation system for proteins(2010) Salazar, Gustavo A; Blake, Edwin HWe designed and developed a Collaborative Annotation System for Proteins called DAS Writeback, which extends the Distributed Annotation System (DAS) to provide the functionalities of adding, editing and deleting annotations. A great deal of e ort has gone into gathering information about proteins over the last few years. By June 2009, UniProtKB/Swiss-Prot, a curated database, contained over four hundred thousand sequence entries and UniProtKB/TrEMBL, a database with automated annotation, contained over eight million sequence entries. Every protein is annotated with relevant information, which needs to be e ciently captured and made available to other research groups. These include annotations about the structure, the function or the biochemical residues. Several research groups have taken on the task of making this information accessible to the community, however, information ow in the opposite direction has not been extensively explored. Users are currently passive actors that behave as consumers of one or several sources of protein annotations and they have no immediate way to provide feedback to the source if, for example, a mistake is detected or they want to add information. Any change has to be done by the owner of the database. The current lack of being able to feed information back to a database is tackled in this project. The solution consists of an extension of the DAS protocol that de nes the communication rules between the client and the writeback server following the Uniform Interface of the RESTful architecture. A protocol extension was proposed to the DAS community and implementations of both server and client were created in order to have a fully functional system. For the development of the server, writing functionalities were added to MyDAS, which is a widely used DAS server. The writeback client is an extended version of the web-based protein client Dasty2. The involvement of the DAS community and other potential users was a fundamental component of this project. The architecture was designed with the insight of the DAS specialized forum, a prototype was then created and subsequently presented in the DAS workshop 2009. The feedback from the forum and workshop was used to rede ne the architecture and implement the system. A usability experiment was performed using potential users of the system emulating a real annotation task. It demonstrated that DAS writeback is e ective, usable and will provide the appropriate environment for the creation and evolution of a protein annotation community. Although the scope of this research is limited to protein annotations, the speci cation was de ned in a general way. It can, therefore, be used for other types of information supported by DAS, implying that the server is versatile enough to be used in other scenarios without major modi cations.
- ItemOpen AccessDesign of a mobile support and content authoring tool to support deaf adults training in computer literacy skills(2016) Ng'ethe, George Gitau; Blake, Edwin HThis dissertation investigates the challenges that Deaf adults encounter at the task of learning computer literacy skills. Deaf adults who communicate using South African Sign Language (SASL) come from poor socio-economic backgrounds are not familiar with the written form of English. They rely on interpreters and Deaf teachers to translate written text into SASL for them to learn computer literacy skill. We present our theme of support, in which Deaf people learn via an intermediary, a teacher or facilitator, in intermediated supported learning. We propose a shift from intermediated supported learning to multimedia supported learning which is most appropriate for the context. Using Community-based co-design we implement two systems: an authoring tool to support lesson content creation by the teacher and a mobile prototype that uses sign language videos to provide computer literacy instruction. We evaluate the two systems to evaluate if they support multimedia-supported learning. The authoring tool allowed the facilitator to create tailored lessons for the Deaf learners using pre-recorded SASL videos and images. The Deaf learners demonstrated ability to do self-paced learning while using the mobile system, better suited to Deaf learners with basic exposure to computer literacy skills.
- ItemOpen AccessDeveloping locally relevant applications for rural South Africa : a telemedicine example(2005) Chetty, Marshini; Blake, Edwin H; Tucker, WilliamWithin developing countries, there is a digital divide between rural and urban areas. In order to overcome this division, we need to provide locally relevant Information and Communication Technology (ICT) services to these areas. Traditional software development methodologies are not suitable for developing software for rural and underserviced areas because they cannot take into account the unique requirements and complexities of such areas. We set out to find the most appropriate way to engineer suitable software applications for rural communities. We developed a methodological framework for creating software applications for a rural community. We critically examined the restrictions that current South African telecommunications legislation places on software development for underserviced areas. Our socially aware computing framework for creating software applications uses principles from Action Research and Participatory Design as well as best practice guidelines; it helps us address all issues affecting the project success. The validity of our framework was demonstrated by using it to create Multi-modal Telemedicine Intercommunicator (MuTI). MuTI is a prototype system for remote health consultation for a rural community. It allowed for synchronous and asynchronous communications between a clinic in one village and a hospital in the neighbouring village, nearly 20 kilometers away, in the Eastern Cape province of South Africa. It used Voice over Internet Protocol (VoIP) combined with a store and forward approach for communication. MuTI was tested over a Wireless Fidelity (WiFi) network for several months.
- ItemOpen AccessDistributed shared memory for virtual environments(1997) Godfrey, Andrew; Blake, Edwin H; MacGregor, KenThis work investigated making virtual environments easier to program, by designing a suitable distributed shared memory system. To be usable, the system must keep latency to a minimum, as virtual environments are very sensitive to it. The resulting design is push-based and non-consistent. Another requirement is that the system should be scaleable, over large distances and over large numbers of participants. The latter is hard to achieve with current network protocols, and a proposal was made for a more scaleable multicast addressing system than is used in the Internet protocol. Two sample virtual environments were developed to test the ease-of-use of the system. This showed that the basic concept is sound, but that more support is needed. The next step should be to extend the language and add compiler support, which will enhance ease-of-use and allow numerous optimisations. This can be improved further by providing system-supported containers.
- ItemOpen AccessAn extended spreadsheet paradigm for data visualisation systems, and its implementation(2000) Nuñez, Fabian; Blake, Edwin HWe describe a data visualisation system which uses spreadsheets as its user interface metaphor. Similar systems implemented in the past were hampered by the contradiction between an imperative formula language and the declarative spreadsheet framework. We have analysed spreadsheets from a data visualisation point of view, and built a system that is an improvement over past efforts to combine spreadsheets and data visualisation. Our prototype combines the following three techniques: we store lists of values in each spreadsheet cell; we use the functional programming language Scheme as the formula language and we make use of lazy evaluation. The novel combination of these techniques makes our system consistently declarative in nature, and gives it several advantages such as small, uncluttered visual programs, the ability to deal with arbitrarily large datasets and the use of advanced functional language features.
- ItemOpen AccessAn extension to optic flow analysis for the generation of computer animated images(1998) Webb, Ian Andrew; Blake, Edwin HThis dissertation seeks to develop image based animation methods using the technique of optic flow analysis developed for a moving planar object. Image based rendering is presented as a class of algorithm using two dimensional shortcuts to the problem of three dimensional animation. The optic flow field is used to develop an image based algorithm based on its use as a description of the diffences between consecutive frames of an animation. A Taylor analysis of the optic flow field is the underlying tool used, breaking the field up into a hierarchy of terms. For a moving planar object, we have considerably simplified the second order Taylor terms into a basis of just two independent terms, which can be related closely to a perspective transformation between frames. Perspective transformations capture exactly the optic flow of a moving planar object. Using the simplified decomposition of the flow field for a moving plane, we decompose the frame to frame transformation into a hierarchy of terms of increasing accuracy and cost. Depending on their accuracy we may choose any of these as transformation on an image between frames, instead of rerendering. The errors in the approximation can be tracked via the Taylor series. This dissertation develops the theory and presents an animation algorithm based on optic flow, and then presents the results of various tests of the algorithm in a variety of simple scenes. The results demonstrate the effectiveness of the algorithm and the time saving achieved in animation.
- ItemOpen AccessExtraction of surface texture data from low quality photographs to aid the construction of virtual reality models of archaeological sites(2001) Williams, John G; Blake, Edwin HA tool has been designed and implemented to use information extracted from photographs captured using uncalibrated cameras (so-called casual photographs) to fill the occlusions which occur in three-dimensional models of photogrammetrically captured sites. Capturing the geometry of archaeological sites by photogrammetric means is relatively expensive and, because of the layouts typical of such sites, usually results in a degree of occlusion. Occlusions are filled by extracting texture and calculating hidden geometry from casual photographs with the support of three-dimensional geometric data gleaned from the photogrammetric survey. The essential philosophy underlying the tool is to segment each occlusion into surfaces which may be approximated using curves and then use known geometry in the region of the occlusion to calculate the most probable locations of the junctions of such surface segments. The tool is primarily a combination of existing techniques for pre-filtering and calibrating the casual photograph, boundary detection and ultimately texture adjustment. The technique implemented for calculating the locations of occluded comers using minimisation of least square errors is new. The tool has been applied to occlusions of the various configurations that are expected to be typical of archaeological sites and has been found to deal well with such features and to provide accurate patches from typical data sets. It is also shown that the three-dimensional geometric model is clearly improved by the filling-in of the occlusion.
- ItemOpen AccessFast and accurate visibility preprocessing(2003) Nirenstein, Shaun; Blake, Edwin HCurrently, the standard approach to visibility preprocessing algorithms is to use a form of approximate solution, known as conservative culling. Such algorithms over-estimate the set of visible polygons. This compromise has been considered necessary in order to perform visibility preprocessing quickly. These algorithms attempt to satisfy the goals of both rapid preprocessing and rapid run-time rendering. We observe, however, that there is a need for algorithms with superior performance in preprocessing, as well as for algorithms that are more accurate. For most applications these features are not required simultaneously. In this thesis we present two novel visibility preprocessing algorithms, each of which is strongly biased toward one of these requirements.
- ItemOpen AccessGesture based interface for asynchronous video communication for deaf people in South Africa(2010) Ramuhaheli, Tshifhiwa; Blake, Edwin HThe preferred method of communication amongst Deaf people is that of sign language. There are problems with the video quality when using the real-time video communication available on mobile phones. The alternative is to use text-based communication on mobile phones, however findings from other research studies show that Deaf people prefer using sign language to communicate with each other rather than text. This dissertation looks at implementing a gesture-based interface for an asynchronous video communication for Deaf people. The gesture interface was implemented on a store and forward video architecture since this preserves the video quality even when there is low bandwidth.
- ItemOpen AccessIncremental volume rendering using hierarchical compression(1996) Haley, Michael Blake; Blake, Edwin HThe research has been based on the thesis that efficient volume rendering of datasets, contained on the Internet, can be achieved on average personal workstations. We present a new algorithm here for efficient incremental rendering of volumetric datasets. The primary goal of this algorithm is to give average workstations the ability to efficiently render volume data received over relatively low bandwidth network links in such a way that rapid user feedback is maintained. Common limitations of workstation rendering of volume data include: large memory overheads, the requirement of expensive rendering hardware, and high speed processing ability. The rendering algorithm presented here overcomes these problems by making use of the efficient Shear-Warp Factorisation method which does not require specialised graphics hardware. However the original Shear-Warp algorithm suffers from a high memory overhead and does not provide for incremental rendering which is required should rapid user feedback be maintained. Our algorithm represents the volumetric data using a hierarchical data structure which provides for the incremental classification and rendering of volume data. This exploits the multiscale nature of the octree data structure. The algorithm reduces the memory footprint of the original Shear-Warp Factorisation algorithm by a factor of more than two, while maintaining good rendering performance. These factors make our octree algorithm more suitable for implementation on average desktop workstations for the purposes of interactive exploration of volume models over a network. This dissertation covers the theory and practice of developing the octree based Shear-Warp algorithms, and then presents the results of extensive empirical testing. The results, using typical volume datasets, demonstrate the ability of the algorithm to achieve high rendering rates for both incremental rendering and standard rendering while reducing the runtime memory requirements.
- ItemOpen AccessInteractive cultural story-telling virtual environments using San stories(2004) Lesaoana, M; Blake, Edwin HStory-telling is being used for the preservation of culture, and interactive story-telling in particular is attractive for its ability to provide the user with a hands-on experience. We explored the feasibility of interactive story-telling in relation to the San culture of South Africa by investigating the effect of interactivity on users' perceived levels of presence. Presence refers to the feeling of being there in a virtual environment (VE presence). We also investigated the level of presence in the story (story presence). Priming as a contributor to presence, and the relationship between VE presence, story presence, and enjoyment were also investigated. These investigations were made based on two virtual environments (one allowing intcraction with the story and the other not interactive) and two priming materials (one relevant to San culture nnd the other not relevant).
- ItemOpen AccessA meta-authoring tool for specifying behaviour in virtual reality environments(2004) Hendricks, Zayd; Marsden, Gary; Blake, Edwin HIn this dissertation, we explore methods for empowering non-programmers with the ability to develop their own virtual environment applications. We explored some of the existing systems to determine what methodologies have already been successfully (or unsuccessfully) applied in the fields of virtual environment systems, authoring tools, and graphical user interfaces. From these methodologies we describe an ideal virtual environment authoring system with which comparisons may be drawn to evaluate existing systems. This ideal system represents a tool ideal in its ability to allow users of differing levels of skill to rapidly create virtual environment applications of any sophistication. Creating such a single, generic authoring tool for every different kind of application is, practically, an impossible task - more so if the authors are non-programmers. A more realistic solution to the problem would be to think of every environment as having a particular context such as a virtual museum or gallery. Creating authoring tools specific to these types of environment contexts greatly reduces the problem. We have therefore produced a progressive meta-authoring system that allows both novice and advanced users to create useful virtual reality applications, allowing the smooth migration of novice users to becoming more experienced. We believe that our system overcomes problems in architecture and support for novice users that can be found in many other authoring systems for virtual environments.
- ItemOpen AccessPerceptual refinement for hierarchical radiosity(2000) Secchia, Adrian; Blake, Edwin H; Holzschuch, NicolasThis dissertation explores the use of a simple model of the human visual system to yield a performance improvement with hierarchical radiosity. Hierarchical radiosity is a physically based rendering algorithm and hence makes no attempt to optimize computation for human perception. We used a model of the edge enhancement properties of the human visual system to produce a perceptually based refinement oracle for the hierarchical radiosity algorithm. Tests of the perceptual oracle shows that it allows the hierarchical radiosity algorithm to produce the same visual quality output in half the time and using half the memory compared to the same algorithm using the standard refinement oracle.
- ItemOpen AccessPresence and co-presence in collaborative virtual environments(2001) Casaneuva, Juan S; Blake, Edwin HPresence in Collaborative Virtual Environments (CVEs) can be defined into personal presence and co-presence. Personal presence is having a feeling of "being there" in the CVE yourself. Co-presence is having a feeling that one is in the same place as the other praticipants, and that one is collaborating with real people. The focus of this research was to conduct exploratory studies to investigate and verify some of the factors believed to affect personal presence and co-presence in a CVE. This was achieved by designing and performing experiments in CVEs, and using subjective measures to assess the levels of personal presence and co-presence in the CVE. In addition, we have developed a subjective measure of co-presence in the form of a pencil-and-paper questionnaire. This co-presence questionnaire was used to measure the amount of co-presence experienced by the participants in the CVE. In this dissertation we describe three experiments used to investigate some of the factors which might affect personal presence and co-presence in a CVE.
- ItemOpen AccessProviding informational support to HIV + women in a virtual environment : a case study comparing the effects of virtual reality and paper media for content delivery(2008) Brown, Sarah; Blake, Edwin HThis dissertation presents a comparison of the effects of two media, VR and paper (i.e. pamphlets) in communicating supportive information to an HIV+ sample group. We created a VE to provide social and informational support for HIV+ people in the South African context. The design of the VE placed emphasis on creating a typically South African space which users could recognize and find familiar. Our research focused on two rooms containing virtual agents and points of possible interaction: the lounge and the kitchen. In the lounge, a HIV/Aids support group was simulated while the kitchen contained two areas which presented nutritional informational support: Diet and Cleanliness & Hygiene.
- ItemOpen AccessQuality control tools for interactive rendering of 3D triangle meshes(2002) Southern, Richard; Blake, Edwin H; Marais, PatrickIn this dissertation we explore methods of quality control of untextured polygonal models. The tools presented build, evaluate and improve on the field of multiresolution analysis through decimation. We evaluate the quality of models generated through various simplification algorithms to develop efficient measures of image quality. We develop an application for selective, progressive and view-dependent refinement, suitable for browsing 3D models on the internet. Existing work in continuous level-of-detail is extended to allow for faster interpolation between LOD sequences and we present a new LOD control mechanism for maintaining a constant polygon count. We present a generic framework generates multiresolution models through simplification. This allows for the comparison of surface compression methods under the same conditions, and to determine the performance of surface quality measures based on these results. These measures of surface quality are evaluated with both image and model based criteria. We find that the declining volume of a simplified object is a good method of predicting view-independent image quality. Using our generic framework, we extend two applications which can be used to improve rendering performance in a virtual environment. We develop a new selective refinement application which refines only a desired region of the model, suitable for online model browsing. This method provides substantial space saving due to a more compact representation of the simplification hierarchy, and also provides optimisations for use with a client/server model. A novel method of defining smooth mappings between different resolution versions of a model (called continuous level-of-detail) is also defined. This technique greatly improves rendering performance of these models by employing commonly available programmable graphics hardware. We also present a method of controlling the number of polygons in large scenes, which is capable of predictively maintaining a constant frame rate by guaranteeing a polygon budget.
- ItemOpen AccessScaffolding java programming on a mobile phone for novice learners(2015) Mbogo, Charity Chao; Blake, Edwin H; Suleman, HusseinThe ubiquity of mobile phones provides an opportunity to use them for learning programming beyond the classroom. This would be particularly useful for novice learners of programming in resource- constrained environments. However, limitations of mobile phones, such as small screens and small keypads, impede their use as typical programming environments. This study proposed that mobile programming environments could include scaffolding techniques specifically designed for mobile phones, and designed based on learners' needs. A six-level theoretic framework was used to design scaffolding techniques to support construction of Java programs on a mobile phone. The scaffolding techniques were implemented on an Android platform. Using the prototype, three experiments were conducted with 182 learners of programming from four universities in South Africa and Kenya. Evaluation was conducted to investigate: (i) which scaffolding techniques could support the construction of Java programs on a mobile phone; and (ii) the effect on learners of using these scaffolding techniques to construct Java programs on a mobile phone. Data was collected using computer logs, questionnaires, and image and video recordings. It was found that static scaffolding, such as a program overview and constructing a program one part at a time, supported the construction of programs on a mobile phone. It was also found that automatic scaffolding, such as error prompts and statement dialogs, and user-initiated scaffolding, such as viewing of the full program while creating parts of a program, supported learners to construct programs on the mobile phone. The study also found that the scaffolding techniques enabled learners to attempt and complete more tasks than a non-scaffolded environment. Further, the scaffolding techniques enabled learners to complete programs efficiently, and captured syntactical errors early during program creation. The results also indicated that after the initial familiarization with the scaffolded environment, the scaffolding techniques could enable faster completion of programs. Learners' feedback indicated that they found the scaffolding techniques useful in supporting programming on a mobile phone and in meeting learners' needs. This study provides empirical evidence that scaffolding techniques specifically designed for mobile phones and designed based on learners' needs could support the construction of programs on a mobile phone.