Exploring Topological Environments

Simultaneous localization and mapping (SLAM) addresses the task of incrementally building a map of the environment with a robot while simultaneously localizing the robot relative to that map. SLAM is generally regarded as one of the most important problems in the pursuit of building truly autonomous mobile robots. This thesis considers the SLAM problem within a topological framework, in which the world and its representation are modelled as a graph. A topological framework provides a useful model within which to explore fundamental limits to exploration and mapping. Given a topological world, it is not, in general, possible to map the world deterministically without resorting to some type of marking aids. Early work demonstrated that a single movable marker was sufficient but is this necessary? This thesis shows that deterministic mapping is possible if both explicit place and back-link information exist in one vertex. Such 'directional lighthouse' information can be established in a number of ways including through the addition of a simple directional immovable marker to the environment. This thesis also explores non-deterministic approaches that map the world with less marking information. The algorithms are evaluated through performance analysis and experimental validation. Furthermore, the basic sensing and locomotion assumptions that underlie these algorithms are evaluated using a differential drive robot and an autonomous visual sensor

Exploring Topological Environments

Simultaneous localization and mapping (SLAM) addresses the task of incrementally building a map of the environment with a robot while simultaneously localizing the robot relative to that map. SLAM is generally regarded as one of the most important problems in the pursuit of building truly autonomous mobile robots. This thesis considers the SLAM problem within a topological framework, in which the world and its representation are modelled as a graph. A topological framework provides a useful model within which to explore fundamental limits to exploration and mapping. Given a topological world, it is not, in general, possible to map the world deterministically without resorting to some type of marking aids. Early work demonstrated that a single movable marker was sufficient but is this necessary? This thesis shows that deterministic mapping is possible if both explicit place and back-link information exist in one vertex. Such 'directional lighthouse' information can be established in a number of ways including through the addition of a simple directional immovable marker to the environment. This thesis also explores non-deterministic approaches that map the world with less marking information. The algorithms are evaluated through performance analysis and experimental validation. Furthermore, the basic sensing and locomotion assumptions that underlie these algorithms are evaluated using a differential drive robot and an autonomous visual sensor

A Web GIS-based Integration of 3D Digital Models with Linked Open Data for Cultural Heritage Exploration

This PhD project explores how geospatial semantic web concepts, 3D web-based visualisation, digital interactive map, and cloud computing concepts could be integrated to enhance digital cultural heritage exploration; to offer long-term archiving and dissemination of 3D digital cultural heritage models; to better interlink heterogeneous and sparse cultural heritage data. The research findings were disseminated via four peer-reviewed journal articles and a conference article presented at GISTAM 2020 conference (which received the ‘Best Student Paper Award’)

Combining Sensors and Multibody Models for Applications in Vehicles, Machines, Robots and Humans

The combination of physical sensors and computational models to provide additional information about system states, inputs and/or parameters, in what is known as virtual sensing, is becoming increasingly popular in many sectors, such as the automotive, aeronautics, aerospatial, railway, machinery, robotics and human biomechanics sectors. While, in many cases, control-oriented models, which are generally simple, are the best choice, multibody models, which can be much more detailed, may be better suited to some applications, such as during the design stage of a new product

VR Technologies in Cultural Heritage

This open access book constitutes the refereed proceedings of the First International Conference on VR Technologies in Cultural Heritage, VRTCH 2018, held in Brasov, Romania in May 2018. The 13 revised full papers along with the 5 short papers presented were carefully reviewed and selected from 21 submissions. The papers of this volume are organized in topical sections on data acquisition and modelling, visualization methods / audio, sensors and actuators, data management, restoration and digitization, cultural tourism

VR Technologies in Cultural Heritage

This open access book constitutes the refereed proceedings of the First International Conference on VR Technologies in Cultural Heritage, VRTCH 2018, held in Brasov, Romania in May 2018. The 13 revised full papers along with the 5 short papers presented were carefully reviewed and selected from 21 submissions. The papers of this volume are organized in topical sections on data acquisition and modelling, visualization methods / audio, sensors and actuators, data management, restoration and digitization, cultural tourism

Localization and Mapping from Shore Contours and Depth

This work examines the problem of solving SLAM in aquatic environments using an unmanned surface vessel under conditions that restrict global knowledge of the robot's pose. These conditions refer specifically to the absence of a global positioning system to estimate position, a poor vehicle motion model, and absence of magnetic field to estimate absolute heading. These conditions are present in terrestrial environments where GPS satellite reception is occluded by surrounding structures and magnetic inference affects compass measurements. Similar conditions are anticipated in extra-terrestrial environments such as on Titan which lacks the infrastructure necessary for traditional positioning sensors and the unstable magnetic core renders compasses useless. This work develops a solution to the SLAM problem that utilizes shore features coupled with information about the depth of the water column. The approach is validated experimentally using an autonomous surface vehicle utilizing omnidirectional video and SONAR, results are compared to GPS ground truth

Investigating evidence of linguistic relativity in Dholuo

Thesis (PhD)--Stellenbosch University, 2022.ENGLISH ABSTRACT: An age old question within the language sciences has been whether linguistic experience influences how people perceive reality. The possible linguistic influence on thought is what is known as linguistic relativity. Experimentally rigorous psycholinguistic approaches provide an understanding of this kind of relationship between language and thought. These empirical techniques have been adopted in this study to investigate evidence of linguistic relativity in Dholuo. The study specifically explores relativity effects as evidenced in the behaviour of Dholuo-EnglishKiswahili (DEK) multilingual individuals. The investigations were carried out under the linguistic domains of stasis (spatial frames) and kinesis (motion events), both wrapped within the spatial realm. Each of the domains was probed both at a linguistic and a non-linguistic level. A total of two hundred and thirty DEK multilingual speakers were engaged through the photo-object spatial reference frames task, the mirror image task, the verbal motion event construal task and the nonverbal motion event categorization task. Additionally, forty first language (L1) Kiswahili speakers were also engaged through the verbal motion event construal task and the non-verbal motion event categorization task. The latter group was included for comparison. These experiments were conducted under different language contexts; for the DEK group, the spatial reference tasks were carried out both in Dholuo and English; the motion event tasks were performed under Dholuo, English and Kiswahili contexts; while the L1-Kiswahili group performed under Kiswahili context. The results of the investigations were analysed and interpreted through the theoretical lenses of the thinking-for-speaking hypothesis, the grammatical aspect approach, multicompetence theory as well as cognitive grammar. For the investigations on spatial reference frames, the findings revealed an unrestricted availability of multiple spatial reference frames in Dholuo – a state referred to as “referential promiscuity”. The multiplicity of the spatial reference frames was linked to but not directly attributed to the multicompetence of the DEK participants. The linguistic promiscuous state of Dholuo provides multiple options for Dholuo speakers to spatially encode phenomena in a way that is missing in other languages which have a single spatial frame. This is a case of linguistic relativity at the linguistic level. In the motion event experiments, the findings revealed that Dholuo construes motion events by focussing on the ongoing phase of the events, a behaviour that is typical of languages that grammatically mark aspectual distinctions. The grammatical aspect hypothesis attributes the preference for the restricted viewpoint to the imperfective (progressive) aspect in these languages. Dholuo thus aligns with grammatical aspect hypothesis as would be expected of aspect languages. The restricted viewpoint of motion event obligatorily imposed on the Dholuo speakers by the imperfective (progressive aspect) in the language is proof of linguistic relativity at the linguistic level. The L1-Kiswahili group’s findings were similar to those of the DEK group. The study however failed to show sufficient evidence of linguistic relativity at the non-linguistic level for both the spatial reference and the motion event investigations. Instead there was evidence of conceptual convergence due to possibly a shared grammatical category of Dholuo, English and Kiswahili at the non-linguistic level of the motion event tasks.AFRIKAANSE OPSOMMING: ʼn Eeue-oue vraagstuk binne die taalwetenskap is of linguistiese ervaring ʼn invloed op mense se werklikheidspersepsie het. Hierdie invloed op die mens se denke staan as linguistiese relatiwiteit bekend. Streng gekontroleerde psigolinguistiese benaderings bied begrip van sodanige verband tussen taal en denke. So ’n genuanseerde empiriese benadering is in hierdie studie gevolg om bewyse van linguistiese relatiwiteit in Dholuo te ondersoek. Die studie ondersoek spesifiek aspekte van relatiwiteit wat herkenbaar is in die gedrag van veeltalige Dholuo-Engels-kiSwahili (DEK) sprekers. Ondersoeke is onderneem binne die linguistiese domeine van stasis (ruimtelike raamwerke) and kinesis (gevalle van beweging), wat beide binne ʼn ruimtelike omgewing gebeur. Elke domein is in diepte op beide ʼn linguistiese en ʼn nie-linguistiese vlak ondersoek. Altesaam tweehonderd en dertig veeltalige DEK sprekers is by die uitvoer van verskeie opdragte betrek: binne ’n ruimtelike foto-voorwerp verwysingsraamwerk, met ’n spieëlbeeldtaak, met verbale interpretasie van ʼn geval van beweging, en met die kategorisering van ʼn nieverbale beweging. Hierby is ʼn bykomende veertigtal eerstetaal (L1) kiSwahili sprekers betrek by verbale interpretasie van ʼn geval van beweging, en by die kategorisering van ʼn nieverbale beweging. Laasgenoemdes is as kontrolegroep betrek. Hierdie ondersoeke is onder verskillende toetsomstandighede uitgevoer; vir die DEK group is die ruimtelike verwysingsraamwerktaak in beide Dholuo en Engels uitgevoer; die taak om ʼn geval van beweging verbaal te interpreteer is binne Dholuo, Engels en kiSwahili kontekste uitgevoer; terwyl die L1- kiSwahiligroep slegs binne ʼn kiSwahili konteks opgetree het. Die bevindinge van hierdie ondersoek is ontleed en geïnterpreteer aan die hand van verskeie teorië: die dink-om-te-praat hipotese, grammatiese aspekbeskouing, multivaardigheidteorie, en kognitiewe grammatika. By die ondersoek van ruimtelike verwysingsraamwerke is gevind dat daar ʼn onbeperkte veelvoud van ruimtelike verwysingsraamwerke in Dholuo beskikbaar is – ʼn geval van sogenaamde “linguistiese promiskuïteit”. Hierdie onbeperkte veelvoud van ruimtelike verwysingsraamwerke hou verband met die multivaardighede van die DEK deelnemers, maar is nie die direkte gevolg daarvan nie. Die linguisties promisku staat van Dholuo bied ’n veelvoud van geleenthede aan Dholuo-sprekers om dinge in ruimtelike verband vas te pen, ʼn aspek wat eenvoudig ontbreek in tale met slegs ʼn enkele ruimtelike verwysingsraamerk. Dit is dus ʼn geval van linguistiese relativitiwiteit op ʼn taalvlak. Met ondersoeke van bewegingsinterpretasies is bevind dat Dholuo gevalle van beweging interpreteer deur aandag te gee aan die onvoltooide aspek van sodanige beweging, gedrag wat eie is aan tale wat onderskeid in grammatiese aspek aantoon. Die grammatiese aspekbenadering skryf hierdie voorkeur vir ʼn beperkte vertrekpunt toe aan die voorkoms van onvoltooide werkwoordvorme binne hierdie tale. Dholuo pas dus in by die grammatiese aspekbenadering , soos te verwagte by tale waar werkwoordelik aspek die klem dra. Die beperkte interpretasie van enige bewegingsmoment wat noodwendig op Dholuo-sprekers deur die onvoltooide aspek van werkwoorde binne die taal afgedwing word, toon linguistiese relatiwiteit op taalvlak. Bevindinge by die L1-kiSwahili groep stem met dié van die DEK groep ooreen. Die studie kon egter op die nieverbale vlak nie genoeg bewyse vir linguistiese relativiteit by ruimtelike verwysing of by bewegingkategorisering vind nie. Daar was eerder bewyse van denkooreenkomste, waarskynlik danksy ʼn gedeelde grammatiese kategorie op nieverbale vlak by die bewegingsgeval ondersoeke binne Dholuo, Engels en kiSwahili.Doctora

Enabling the Development and Implementation of Digital Twins : Proceedings of the 20th International Conference on Construction Applications of Virtual Reality

Welcome to the 20th International Conference on Construction Applications of Virtual Reality (CONVR 2020). This year we are meeting on-line due to the current Coronavirus pandemic. The overarching theme for CONVR2020 is "Enabling the development and implementation of Digital Twins". CONVR is one of the world-leading conferences in the areas of virtual reality, augmented reality and building information modelling. Each year, more than 100 participants from all around the globe meet to discuss and exchange the latest developments and applications of virtual technologies in the architectural, engineering, construction and operation industry (AECO). The conference is also known for having a unique blend of participants from both academia and industry. This year, with all the difficulties of replicating a real face to face meetings, we are carefully planning the conference to ensure that all participants have a perfect experience. We have a group of leading keynote speakers from industry and academia who are covering up to date hot topics and are enthusiastic and keen to share their knowledge with you. CONVR participants are very loyal to the conference and have attended most of the editions over the last eighteen editions. This year we are welcoming numerous first timers and we aim to help them make the most of the conference by introducing them to other participants