Although the positional accuracy of spatial data has long been of fundamental importance in GIS, it is still largely unknown for linear features. This is compromising the ability of GIS practitioners to undertake accurate geographic analysis and hindering GIS in fulfilling its potential as a credible and reliable tool. As early as 1987 the US National Center for Geographic Information and Analysis identified accuracy as one of the key elements of successful GIS implementation. Yet two decades later, while there is a large body of geodetic literature addressing the positional accuracy of point features, there is little research addressing the positional accuracy of linear features, and still no accepted accuracy model for linear features. It has not helped that national map and data accuracy standards continue to define accuracy only in terms of “well-defined points”. This research aims to address these shortcomings by exploring the effect on linear feature positional accuracy of feature type, complexity, segment length, vertex proximity and e-scale, that is, the scale of the paper map from which the data were originally captured or to which they are customised for output. / The research begins with a review of the development of map and data accuracy standards, and a review of existing research into the positional accuracy of linear features. A geographically sensible error model for linear features using point matching is then developed and a case study undertaken. Features of five types, at five e-scales, are selected from commonly used, well-regarded Australian topographic datasets, and tailored for use in the case study. Wavelet techniques are used to classify the case study features into sections based on their complexity. Then, using the error model, half a million offsets and summary statistics are generated that shed light on the relationships between positional accuracy and e-scale, feature type, complexity, segment length, and vertex proximity. Finally, auto-regressive time series modelling and moving block bootstrap analysis are used to correct the summary statistics for correlation. / The main findings are as follows. First, metadata for the tested datasets significantly underestimates the positional accuracy of the data. Second, positional accuracy varies with e-scale but not, as might be expected, in a linear fashion. Third, positional accuracy varies with feature type, but not as the rules of generalisation suggest. Fourth, complex features lose accuracy faster than less complex features as e-scale is reduced. Fifth, the more complex a real-world feature, the worse its positional accuracy when mapped. Finally, accuracy mid-segment is greater than accuracy end-segment.

Bibliography: pages 77-83. / This thesis describes some of the communal land tenure systems pertaining to Namibia. Understandably, lands held under communal land tenure have tended to be neither fully documented nor legally and explicitly formalised; communal land tenure systems have been through the mercy of arbitrary action by the state, private individuals or other institutions (S.A Government, 1996: 43). The study attempts to examine the issues involved in the design of a communal land tenure information system for Namibia. It therefore seeks to examine the possibility of using information technology to plan and manage customarily held land, the requirement for an effective design and implementation of such a system and the method of designing such an information system to make room for continual improvement and the addition of finer detail. The research begins with an in-depth literature review of the communal land tenure systems in Namibia and a description of similar information systems. This is followed by the research methodology, which describes the technique used for collecting, analysing and presenting the results of the study. The needs analysis and the data structure contained in the atlas are outlined. The fundamental concepts of database design and the various steps taken by the author to design and construct the land tenure database model for the dissertation are also discussed. The pilot project is analysed, taking into account the capability of the system, its success in terms of a needs analysis, and the adequacy of the data. It specifically analyses the design in the light of social relationships, person or group interests and the spatial component of communal land tenure systems with respect to each area. In addition, it seeks to answer the question whether the tool fits the communal land tenure system, discusses the strengths and weaknesses of the overall system design and the implementation strategies. It is envisaged that, with the provision of the information system in union with its database, this will help to identify and document a communal land tenure system. For the rural dweller or farmer, this system will provide a pictorial image of what is really happening on the ground. The information system could later be upgraded and fully implemented, enabling individuals to effectively plan activities around the existing circumstances and conditions. The recommendation that came out from the study was that given the limited information available on communal land tenure systems, more effort should be spent to study and gather data on the system. It is strongly recommended, therefore, that research into conditions in the communal areas be regarded as a top pri01ity by the Government of Namibia. This could lead to a richer information base in the communal areas to be utilised to improve the lifestyle of the rural communities. Thus, the prototype project designed in this thesis should be implemented fully and later developed and incorporated into an information system which, in the past, has lacked communal land tenure input. The research could not touch on all the communal land tenure areas in Namibia. It is therefore advised that the rest should be investigated in more detail. The inheritance and conflict resolution mechanism which were not modelled effectively should also be reinvestigated.

Bibliography: pages 105-107. / Information Systems, both paper-based and computer-based, are integral in the management of irregular settlements and the process of delivering low-cost housing in South Africa. An Irregular Settlement can be defined as an area where the 'shacks' have no fixed street address. Due to policies by previous regimes, under whose rule irregular settlements were almost ignored, there is often little or no spatial or socio-economic data available about existing irregular settlements. Thus for the use of the community, or to organisations interested in helping to improve the quality of life of the residents living in these settlements. As a prerequisite to quality of life, the basic need of shelter, along with food, healthcare and education need to be made available. The emphasis today is thus being placed on the provision of low-cost housing. A need thus arises to have up-to-date information about these irregular settlements in order to plan either for the upgrading of the settlement or for the relocation to new low-cost housing developments. Currently mostly paper-based systems are being used in these developments. There are two opportunities where computer-oriented information systems could be used at this time in 1996 and 1997 to assist with the management and upgrading of irregular settlements. The first is the stage of managing an existing irregular settlement; the second is managing the process of housing provision, taking advantage of the project-linked subsidy scheme. Two Cape Town based projects provide case studies for the application of information systems at the two stages identified above. The first is the Marconi Beam 'From Shacks to Houses' project located in Milnerton. The second is the Integrated Services Land Project (iSLP) of the Cape Flats. The Marconi Beam Settlement is an irregular settlement that has been accepted as part of the 'Project-Linked Subsidy Scheme' for the provision of new low-cost housing. Previously only paper-based systems were being used to manage the settlement and its move to the new Joe Slovo Park formal housing development. There was also found to be a lack of appropriate tools and awareness of which technology could be used in the process. Some of the specific application areas in which we were able to provide solutions in Marconi Beam included: ■ the identification of people directly affected by the fire that swept through the settlement in October 1996; ■ the residents who would be affected by the construction of a new road through the one area of the settlement could be identified, facilitating their movement away from the area; and ■ a system of tracking the internal moves of residents was devised by which we were able to maintain a record of the internal movements of residents whilst the system of the lottery was in place. Subsequently, with the use of the Block System, the identification of residents who were required to come in and have their applications for new houses processed, as a result of their spatial location in the settlement, was accomplished. The Indlu Management System, a computer based system, resulted from the need to keep track of, and process, large amounts of socio-economic data in order to speedily process the large number of applicants applying for national housing subsidies. As a result of the implementation of this system, the processing times per applicant have been reduced from 30 minutes to 10 minutes per applicant. The successful use of these systems in the two projects demonstrate that there is thus a definite role to be played in the use of information systems in relation to the management of irregular settlements and the provision of low-cost housing.

<p>Den 1 februari 2007 bytte Lantmäteriet referenssystem till SWEREF 99. Anledningen till att kommuner, myndigheter och andra användare också bör byta till SWEREF 99 är att ett gemensamt referenssystem ger ett flertal fördelar, bland annat kommer informationsutbyte att underlättas inom Sverige och användare av GNSS mottagare (Global Navigation Satellite System) kommer inte att behöva bekymra sig över olika koordinatsystem.</p><p>Syftet med denna C-uppsats på 10 poäng är att underlätta för kommuner och organisationer som skall byta referenssystem.</p><p>En handledning för hur kommuner skall lägga upp arbetet med referenssystembytet samt vad kommunen bör ta hänsyn till under inmätningar av kompletteringspunkter som ligger till grund för kommunens transformation presenteras. Geografisk bunden information finns på ett stort antal förvaltningar och bolag inom kommuner och för att inte missa någon organisation vid ett referenssystembyte har vi gjort en undersökning av vilken data som bör transformeras. Kontroll av två transformationsfunktioner som finns i ArcMap jämförs med en transformation i programmet GTRANS och inmätta koordinater med GNSS teknik för att undersöka avvikelserna vid ett framtida byte av referenssystem.</p><p>För att räta upp kommunens nuvarande referenssystem görs inmätningar med GNSS teknik. Detta för att punktkoordinater ska fås i såväl SWEREF 99 som frånsystemet. Dessa punkter skall hålla en hög noggrannhet i det kommunala nätet. Resultatet från transformationerna i ArcMap och i GTRANS minimerar de spänningar och deformationer som kan finnas i det kommunala stomnätet. Antalet kända punkter i transformationssambandet är fler i ArcMap än i GTRANS och vid en jämförelse inom ett mindre område visar ArcMaps två metoder det bästa resultatet.</p> / <p>On February 1st 2007 the National land survey of Sweden changed reference system to the Swedish realisation of European Terrestrial Reference System 1989 (ETRS 89), SWEREF 99. The reason why municipalities, authorities and other users should use SWEREF 99 instead of other reference systems is because the advantages outweigh the disadvantages. The change of reference system should be implemented in order to facilitate the exchange of information inside Sweden and so that the users of GNSS receivers (Global Navigation Satellite System) can refer to the municipality coordinate system easier.</p><p>The aim with this 10 point thesis, on C-level, is to suggest solutions for municipalities and organizations that are changing reference system.</p><p>The study results in a supervision for municipalities’ work procedures at a change of reference system, and show what they should consider during measuring of complement points to underlie their transformation. Geographic information is accessible in a large number of administrations and companies in the municipality. To avoid missing any organization at a change of reference system, an investigation of which data should be transformed has been made. A surveillance of two transformation functions in ArcMap and one in GTRANS are compared with GNSS technique measured coordinates for comparison divergence between the transformations in a future change of reference system.</p><p>Measurements with GNSS technique are made to improve the present reference system in the municipality. The measurements are made because coordinates shall be present in SWEREF 99 as well as the from-system. These points shall keep a high accuracy with respect to equipment, method of measuring etc. The result from the transformations in ArcMap and GTRANS minimize the tensions and deformations in the municipal horizontal geodetic control network in different ways in relation to the coordinates. The numbers of known points in relationship for transformations are larger in ArcMap than GTRANS, a comparison in a small area in central Gävle shows that ArcMaps results are better than GTRANS.</p>

Den 1 februari 2007 bytte Lantmäteriet referenssystem till SWEREF 99. Anledningen till att kommuner, myndigheter och andra användare också bör byta till SWEREF 99 är att ett gemensamt referenssystem ger ett flertal fördelar, bland annat kommer informationsutbyte att underlättas inom Sverige och användare av GNSS mottagare (Global Navigation Satellite System) kommer inte att behöva bekymra sig över olika koordinatsystem. Syftet med denna C-uppsats på 10 poäng är att underlätta för kommuner och organisationer som skall byta referenssystem. En handledning för hur kommuner skall lägga upp arbetet med referenssystembytet samt vad kommunen bör ta hänsyn till under inmätningar av kompletteringspunkter som ligger till grund för kommunens transformation presenteras. Geografisk bunden information finns på ett stort antal förvaltningar och bolag inom kommuner och för att inte missa någon organisation vid ett referenssystembyte har vi gjort en undersökning av vilken data som bör transformeras. Kontroll av två transformationsfunktioner som finns i ArcMap jämförs med en transformation i programmet GTRANS och inmätta koordinater med GNSS teknik för att undersöka avvikelserna vid ett framtida byte av referenssystem. För att räta upp kommunens nuvarande referenssystem görs inmätningar med GNSS teknik. Detta för att punktkoordinater ska fås i såväl SWEREF 99 som frånsystemet. Dessa punkter skall hålla en hög noggrannhet i det kommunala nätet. Resultatet från transformationerna i ArcMap och i GTRANS minimerar de spänningar och deformationer som kan finnas i det kommunala stomnätet. Antalet kända punkter i transformationssambandet är fler i ArcMap än i GTRANS och vid en jämförelse inom ett mindre område visar ArcMaps två metoder det bästa resultatet. / On February 1st 2007 the National land survey of Sweden changed reference system to the Swedish realisation of European Terrestrial Reference System 1989 (ETRS 89), SWEREF 99. The reason why municipalities, authorities and other users should use SWEREF 99 instead of other reference systems is because the advantages outweigh the disadvantages. The change of reference system should be implemented in order to facilitate the exchange of information inside Sweden and so that the users of GNSS receivers (Global Navigation Satellite System) can refer to the municipality coordinate system easier. The aim with this 10 point thesis, on C-level, is to suggest solutions for municipalities and organizations that are changing reference system. The study results in a supervision for municipalities’ work procedures at a change of reference system, and show what they should consider during measuring of complement points to underlie their transformation. Geographic information is accessible in a large number of administrations and companies in the municipality. To avoid missing any organization at a change of reference system, an investigation of which data should be transformed has been made. A surveillance of two transformation functions in ArcMap and one in GTRANS are compared with GNSS technique measured coordinates for comparison divergence between the transformations in a future change of reference system. Measurements with GNSS technique are made to improve the present reference system in the municipality. The measurements are made because coordinates shall be present in SWEREF 99 as well as the from-system. These points shall keep a high accuracy with respect to equipment, method of measuring etc. The result from the transformations in ArcMap and GTRANS minimize the tensions and deformations in the municipal horizontal geodetic control network in different ways in relation to the coordinates. The numbers of known points in relationship for transformations are larger in ArcMap than GTRANS, a comparison in a small area in central Gävle shows that ArcMaps results are better than GTRANS.

The essence of this thesis may be described by Ruther's argument that the survey profession is confronted with the necessity of having to redefine its role in society, or face the consequences of having the profession become marginalised (n .d: 1). The thesis reviews the functions of a traditional land surveyor, and shows how these functions are diminishing. This is done to illustrate the need for change in the profile of a traditional land surveyor, and the necessity of him redefining his role in society, in order to prosper in the future. The concept of geomatics, as an integrated approach to the acquisition and management of spatial data is introduced, and is used to illustrate the types of skills which a traditional land surveyor already has, and would need to acquire, in order to make the transition to a modern land surveyor, or what is tenned a geomaticist. A case study is then carried out in order to test the validity of the conceptual framework. / Thesis (M.Sc.Sur)-University of Natal, Durban, 2000.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 200-263).

Plus de la moitié de la population mondiale vit de nos jours dans les villes. Cette proportion s'élève à 77.5% en France. La densité importante de la population urbaine provoque plusieurs problèmes environnementaux tels que les bruits, les canicules urbaines, les pollutions chimiques ou la pollution magnétique. Dans une ville, les habitants pourraient obtenir des informations sur ces phénomènes grâce aux infrastructures informatiques et au partage de l'information entre services techniques et citoyens. Si l'un des objectifs des villes intelligentes est d'améliorer la gestion des ressources - comme l'eau et l'électricité - un autre est de pouvoir contrôler jour après jour ce qui se passe dans la ville au niveau du climat et des pollutions en collectant des informations locales et en les affichant sur un portail public. Mais ces informations, généralement transmises sous forme de graphiques ou de cartes, ne sont pas faciles à interpréter. L’objectif de cette thèse est de proposer des solutions pour améliorer la représentation cartographique de phénomènes urbains dans leur contexte géographique afin que celle-ci soit facile à comprendre aussi bien pour les services techniques, que pour le grand public non spécialistes de ces phénomènes.Afin de faciliter la perception d’une carte de phénomène, nous proposons une représentation à différents niveaux de détail, une variété de choix de l’espace cartographique ; des symboles simples et adaptifs au phénomène et une identification automatique de zones particulières. Pour les niveaux de détail, nous adaptons la densité graphique aux différents niveaux de détail (optimisation préparatoire dans la base de données) et à l’échelle courante de visualisation (optimisation dynamique et interactive avec l’utilisateur). Pour le choix de l’espace cartographique, un phénomène peut être représenté sur l’ensemble de bâtiments, sur les rues ou sur une structure de géométrie quelconque saisie par l’utilisateur. Enfin pour l’identification automatique de zones particulières, nous identifions les valeurs extrêmes, dépassant le seuil de dangerosité ou les zones de forte dispersion de valeur importante, pour permettre à l’utilisateur de les localiser rapidement. Nous avons proposé aussi d’ajouter le concept de l’observateur et d’adapter la visualisation selon la position de l’observateur afin de diminuer la superposition entre les présentations 3D de différents niveaux de hauteur d’un phénomène, lorsqu’il varie en fonction de l’altitude (et qu’on dispose de ces données) / More than half of the world's population now lives in cities. This proportion is 77.5% in France. The high density of the urban population causes several environmental problems such as noise, urban heat waves, chemical pollution or magnetic pollution. In a city, the inhabitants could get all the information by the computer infrastructures and the information sharing between the citizens themselves. If one of the objectives of smart cities is to improve the management of resources - such as water and electricity - another is to be able to control day by day what is happening in the city in terms of climate and pollution by collecting local information and mapping it in the public portal of cartography. Although the link between civic services, the interactions between people and government institutions is very important, the concerned information, usually represented by graphics or maps, is not easy to for all people to understand and to interpret. Thus the objective of this thesis is to propose solutions to improve the representation of urban phenomena with their geographical context and at different levels of detail so that it becomes easy to understand for the general public.In order to facilitate the perception of a phenomenon map, we propose a representation at different levels of detail, from the most general to the most detailed and to adapt the graphic density to the level of detail (preparatory optimization in the database) and to the current visualization scale (dynamic and interactive optimization with the user); a various choices of the cartographic space, for example a phenomenon may be represented on the set of buildings or streets, or on any structure of geometry chosen by the user; simple and adaptive symbols to the phenomenon; and an automatic identification of particular zones: with extreme values, exceeding the threshold of dangerousness or with a large dispersion, this allows the user to quickly locate areas of interest throughout the visualization. We also proposed to add the concept of observer and adapt the visualization according to the position of the observer in order to reduce the superposition between the 3D presentations of different levels of height of a phenomenon, when it varies according to of the altitude (and that these data are available)

Ces dernières années, le besoin de données géographiques de référence a significativement augmenté. Pour y répondre, il est nécessaire de mettre jour continuellement les données de référence existantes. Cette tâche est coûteuse tant financièrement que techniquement. Pour ce qui concerne les réseaux routiers, trois types de voies sont particulièrement complexes à mettre à jour en continu : les chemins piétonniers, les chemins agricoles et les pistes cyclables. Cette complexité est due à leur nature intermittente (elles disparaissent et réapparaissent régulièrement) et à l’hétérogénéité des terrains sur lesquels elles se situent (forêts, haute montagne, littoral, etc.).En parallèle, le volume de données GPS produites par crowdsourcing et disponibles librement augmente fortement. Le nombre de gens enregistrant leurs positions, notamment leurs traces GPS, est en augmentation, particulièrement dans le contexte d’activités sportives. Ces traces sont rendues accessibles sur les réseaux sociaux, les blogs ou les sites d’associations touristiques. Cependant, leur usage actuel est limité à des mesures et analyses simples telles que la durée totale d’une trace, la vitesse ou l’élévation moyenne, etc. Les raisons principales de ceci sont la forte variabilité de la précision planimétrique des points GPS ainsi que le manque de protocoles et de métadonnées (par ex. la précision du récepteur GPS).Le contexte de ce travail est l’utilisation de traces GPS de randonnées pédestres ou à vélo, collectées par des volontaires, pour détecter des mises à jours potentielles de chemins piétonniers, de voies agricoles et de pistes cyclables dans des données de référence. Une attention particulière est portée aux voies existantes mais absentes du référentiel. L’approche proposée se compose de trois étapes : La première consiste à évaluer et augmenter la qualité des traces GPS acquises par la communauté. Cette qualité a été augmentée en filtrant (1) les points extrêmes à l’aide d’un approche d’apprentissage automatique et (2) les points GPS qui résultent d’une activité humaine secondaire (en dehors de l’itinéraire principal). Les points restants sont ensuite évalués en termes de précision planimétrique par classification automatique. La seconde étape permet de détecter de potentielles mises à jour. Pour cela, nous proposons une solution d’appariement par distance tampon croissante. Cette distance est adaptée à la précision planimétrique des points GPS classifiés pour prendre en compte la forte hétérogénéité de la précision des traces GPS. Nous obtenons ainsi les parties des traces n’ayant pas été appariées au réseau de voies des données de référence. Ces parties sont alors considérées comme de potentielles voies manquantes dans les données de référence. Finalement nous proposons dans la troisième étape une méthode de décision multicritère visant à accepter ou rejeter ces mises à jour possibles. Cette méthode attribue un degré de confiance à chaque potentielle voie manquante. L’approche proposée dans ce travail a été évaluée sur un ensemble de trace GPS multi-sources acquises par crowdsourcing dans le massif des Vosges. Les voies manquantes dans les données de références IGN BDTOPO® ont été détectées avec succès et proposées comme mises à jour potentielles / Nowadays, the need for very up to date authoritative spatial data has significantly increased. Thus, to fulfill this need, a continuous update of authoritative spatial datasets is a necessity. This task has become highly demanding in both its technical and financial aspects. In terms of road network, there are three types of roads in particular which are particularly challenging for continuous update: footpath, tractor and bicycle road. They are challenging due to their intermittent nature (e.g. they appear and disappear very often) and various landscapes (e.g. forest, high mountains, seashore, etc.).Simultaneously, GPS data voluntarily collected by the crowd is widely available in a large quantity. The number of people recording GPS data, such as GPS traces, has been steadily increasing, especially during sport and spare time activities. The traces are made openly available and popularized on social networks, blogs, sport and touristic associations' websites. However, their current use is limited to very basic metric analysis like total time of a trace, average speed, average elevation, etc. The main reasons for that are a high variation of spatial quality from a point to a point composing a trace as well as lack of protocols and metadata (e.g. precision of GPS device used).The global context of our work is the use of GPS hiking and mountain bike traces collected by volunteers (VGI traces), to detect potential updates of footpaths, tractor and bicycle roads in authoritative datasets. Particular attention is paid on roads that exist in reality but are not represented in authoritative datasets (missing roads). The approach we propose consists of three phases. The first phase consists of evaluation and improvement of VGI traces quality. The quality of traces was improved by filtering outlying points (machine learning based approach) and points that are a result of secondary human behaviour (activities out of main itinerary). Remained points are then evaluated in terms of their accuracy by classifying into low or high accurate (accuracy) points using rule based machine learning classification. The second phase deals with detection of potential updates. For that purpose, a growing buffer data matching solution is proposed. The size of buffers is adapted to the results of GPS point’s accuracy classification in order to handle the huge variations in VGI traces accuracy. As a result, parts of traces unmatched to authoritative road network are obtained and considered as candidates for missing roads. Finally, in the third phase we propose a decision method where the “missing road” candidates should be accepted as updates or not. This decision method was made in multi-criteria process where potential missing roads are qualified according to their degree of confidence. The approach was tested on multi-sourced VGI GPS traces from Vosges area. Missing roads in IGN authoritative database BDTopo® were successfully detected and proposed as potential updates

Foi estruturado um modelo de servidor de mapas, na plataforma MapGuide, capaz de disseminar eletrônicamente os dados geoespaciais gerados pela Prefeitura de Taboão da Serra SP. O projeto de servidor visou duas finalidades principais: implementar este tipo de tecnologia ao analista responsável pelo projeto, no âmbito da Prefeitura, e; tornar a dissertação um guia teóricometodológico introdutório a profissionais da Cartografia e Geociências, não especializados com este ramo das geotecnologias. O serviço de disseminação foi configurado para servir dados geoespaciais diretamente a navegadores de rede, servidores FTP e Sistemas de Informação Geográfica (SIG). Para estes últimos, foram utilizados recursos de acesso a dados localizados em servidores de mapas remotos, por meio dos serviços de Web Mapping Service (WMS) e Web Feature Service (WFS). Enquanto a disseminação em navegador de rede pode alcançar usuários não especializados com este campo das geotecnologias, a utilização de servidores FTP, serviços WMS e WFS remotos, favorece usuários técnicos das Geociências e Cartografia. Comparou-se as funcionalidades do MapGuide, a SIG de primeira e segunda geração, com funções topológicas completas. Concluiu-se que o servidor de mapas não possuía a mesma capacidade de análise espacial dos SIG topológicos. / A Web Mapping application built on MapGuide was designed to digitally serve the municipal government of Taboão da Serra SP geospatial data. There were two aims related to the application project: to implement the technology to the analyst responsible for the project, and; to develop the project content as an introdutory theoretical-methodological guide to geoscientists and cartographers not specialized in the internet mapping field. The geospatial data dissemination services were configured to web browsers, FTP servers and Geographic Information Systems (GIS). For these lasts, data access resources to remote spatial servers were used, via Web Mapping Services (WMS) and Web Feature Services (WFS). While the web browser data dissemination is suitable for non-technicians, the FTP server, WMS and WFS resources, are best suitable for GIS analysts. A comparison between MapGuide functionalities with other first and second generation topological GIS softwares was performed. The conclusion revealed the web mapping application didn\'t have the same spatial analysis capabilities as the topological GIS.