OpenStreetMap (OSM) is the largest and objectively the most successful project from all attempts to open-source alternative to commercial map databases and projects of the official agencies. OSM is widely popular in Czech Republic, but the quality of this VGI (volunteered geographic information) dataset has not yet been studied. This master thesis evaluates several aspects of quantifiable characteristics of buildings in Prague. The objective was to primarily evaluate completeness, semantic accuracy and shape accuracy of building footprints. Data from OSM were compared with Digital map of Prague by Geoportal Prague, which is the official map resource covering the area of the city Prague. The data processing was done in ArcGIS by the ESRI company. The results show that OSM in Prague have high semantic accuracy and almost 100% completeness in terms of total area, but more than 50% of buildings are missing basic descriptive data. In terms of shape accuracy the footprints were identified by smaller amount of vertices than the footprints from Geoportal Prague and in some cases certain architectural details were missing.

Lantmäteriet arbetar med att säkra ägandet av fastigheter och att tillgängliggöra geo data tillsamhället. Enheten för Geografisk information samlar in en stor mängd geografiskaobjekttyper exempelvis väg, vandringsled och camping. Vissa av dessa samlas in med hjälpav flygbildstolkning medan andra objekt samlas in genom att information hämtas från internetgenom kontakter med intresseorganisation eller ute i fältet. Enheten brukar lägga mycket tidpå att identifiera objekt som är svåra att tolka i flygbilder. En sådan process kallas förflygbildstolkning och är den största produktionslinjen för att uppdatera Sveriges kartor medgeografisk information. Rapporten beskriver crowdsourcing och möjligheterna som finns meddet arbetet och hur det bidrar till Lantmäteriet. Potentiella objekt som kan samlas från allmäneller antigen riktad crowdsoucing och hur detta kan underlätta för Lantmäteriet är huvudsyftetmed rapporten.Via crowdsourcing kan till exempel aktörer som inte är anställda på företaget bidra till attförbättra kvaliteten på den geografiska informationen hos Lantmäteriet. Det kan vara såvälprivatpersoner som professionella yrkesmän som gör detta på sin fritid. Det finns flera typerav crowdsourcing, därmed är målet att fördjupa sig i ämnet och redogöra för potentiellamöjligheter för Lantmäteriet att använda sig av crowdsourcing på olika sätt som effektiviserardet egna arbetet för den topografiska enheten. Rapporten tar även upp hur olika länder arbetarmed topografisk crowdsourcing inom detta område, i detta fall är Länder Schweiz, Hollandoch Frankrike för att kunna få inspiration av deras arbete och eventuella framgångar. Utöverandra länder jämförs även några kommuner i syfte att ta reda på om de arbetar medcrowdsourcing inom detta område eller inte, och om de gör det, hur de gör. I rapporten tas 6frågeställningar upp och som även besvaras längre ner i rapporten för att kunna få en tydligarebild av det hela. För att kunna få dessa frågeställningar har Lantmäteriets Wiki, som är eninformationssida som innehåller både äldre och nyare studier av crowdsourcing somLantmäteriet har gjort, använts som både underlag, stöd och inspiration. Rapporten tar ävenupp om Lantmäteriet ska ha en öppen eller direkt crowdsourcing, eller kanske både och, samtvarför just den lösningen passar bäst för verksamheten.

This thesis takes a multidisciplinary approach to understanding the unique abilities of Volunteered Geographic Information (VGI) to enhance the utility of online mashups in ways not achievable with Professional Geographic Information (PGI). The key issues currently limiting the use of successful of VGI are the concern for quality, accuracy and value of the information, as well as the polarisation and bias of views within the user community. This thesis reviews different theoretical approaches in Human Factors, Geography, Information Science and Computer Science to help understand the notion of user judgements relative to VGI within an online environment (Chapter 2). Research methods relevant to a human factors investigation are also discussed (Chapter 3). (Chapter 5) The scoping study established the fundamental insights into the terminology and nature of VGI and PGI, a range of users were engaged through a series of qualitative interviews. This led the development of a framework on VGI (Chapter 4), and comparative description of users in relation to one another through a value framework (Chapter 5). Study Two produced qualitative multi-methods investigation into how users perceive VGI and PGI in use (Chapter 6), demonstrating similarities and the unique ability for VGI to provide utility to consumers. Chapter Seven and Study Three brought insight into the specific abilities for VGI to enhance the user judgement of online information within an information relevance context (Chapter 7 and 8). In understanding the outcomes of these studies, this thesis discusses how users perceive VGI as different from PGI in terms of its benefit to consumers from a user centred design perspective (Chapter 9). In particular, the degree to which user concerns are valid, the limitation of VGI in application and its potential strengths in enriching the user experiences of consumers engaged within an information search. In conclusion, specific contributions and avenues for further work are highlighted (Chapter 10).

Conventionally geographic data produced and disseminated by the national mapping agencies are used for studying various urban issues. These data are not commonly available or accessible, but also are criticized for being expensive. However, this trend is changing along with the rise of Volunteered Geographic Information (VGI). VGI, known as user generated content, is the geographic data collected and disseminated by individuals at a voluntary basis. So far, a huge amount of geographic data has been collected due to the increasing number of contributors and volunteers. More importantly, they are free and accessible to anyone.   There are many formats of VGI such as Wikimapia, Flickr, GeoNames and OpenStreetMap (OSM). OSM is a new mapping project contributed by volunteers via a wiki-like collaboration, which is aimed to create free, editable map of the entire world. This thesis adopts OSM as the main data source to uncover the hidden patterns around the urban systems. We investigated some fundamental issues such as city rank size law and the measurement of urban sprawl. These issues were conventionally studied using Census or satellite imagery data.   We define the concept of natural cities in order to assess city size distribution. Natural cities are generated in a bottom up manner via the agglomeration of individual street nodes. This clustering process is dependent on one parameter called clustering resolution. Different clustering resolutions could derive different levels of natural cities. In this respect, they show little bias compared to city boundaries imposed by Census bureau or extracted from satellite imagery. Based on the investigation, we made two findings about rank size distributions. The first one is that all the natural cities in US follow strictly Zipf’s law regardless of the clustering resolutions, which is different from other studies only investigating a few largest cities. The second one is that Zipf’s law is not universal at the state level, e.g., Zipf’s law for natural cities within individual states does not hold valid.   This thesis continues to detect the sprawling based on natural cities. Urban sprawl devours large amount of open space each year and subsequently leads to many environmental problems. To curb urban sprawl with proper policies, a major problem is how to objectively measure it. In this thesis, a new approach is proposed to measure urban sprawl based on street nodes. This approach is based on the fact that street nodes are significantly correlated with population in cities. Specifically, it is reported that street nodes have a linear relationship with city sizes with correlation coefficient up to 0.97. This linear regression line, known as sprawl ruler, can partition all cities into the sprawling, compact and normal cities. This study verifies this approach with some US census data and US natural cities. Based on the verification, this thesis further applies it to three European countries: France, Germany and UK, and consequently categorizes all natural cities into three classes: sprawling, compact and normal. This categorization provides a new insight into the sprawling detection and sets a uniform standard for cross comparing sprawling level across an entire country. / QC 20101206

This thesis aims to seek interesting patterns from massive amounts of Flickr data in Sweden with pro- posed new clustering strategies. The aim can be further divided into three objectives. The first one is to acquire large amount of timestamped geolocation data from Flickr servers. The second objective is to develop effective and efficient methods to process the data. More specifically, the methods to be developed are bifold, namely, the preprocessing method to solve the “Big Data” issue encountered in the study and the new clustering method to extract spatio-temporal patterns from data. The third one is to analyze the extracted patterns with scaling analysis techniques in order to interpret human social activities underlying the Flickr Data within the urban envrionment of Sweden. During the study, the three objectives were achieved sequentially. The data employed for this study was vector points downloaded through Flickr Application Programming Interface (API). After data ac- quisition, preprocessing was performed on the raw data. The whole dataset was firstly separated by year based on the temporal information. Then data of each year was accumulated with its former year(s) so that the evovling process can be explored. After that, large datasets were splitted into small pieces and each piece was clipped, georeferenced, and rectified respectively. Then the pieces were merged together for clustering. With respect to clustering, the strategy was developed based on the Delaunay Triangula- tion (DT) and head/tail break rule. After that, the generated clusters were analyzed with scaling analysis techniques and spatio-temporal patterns were interpreted from the analysis results. It has been found that the spatial pattern of the human social activities in the urban environment of Sweden generally follows the power-law distribution and the cities defined by human social activities are evolving as time goes by. To conclude, the contributions of this research are threefold and fulfill the objectives of this study, respectively. Firstly, large amount of Flickr data is acquired and collated as a contribution to other aca- demic researches related to Flickr. Secondly, the clustering strategy based on the DT and head/tail break rule is proposed for spatio-temporal pattern seeking. Thirdly, the evolving of the cities in terms of human activities in Sweden is detected from the perspective of scaling. Future work is expected in major two aspects, namely, data and data processing. For the data aspect, the downloaded Flickr data is expected to be employed by other studies, especially those closely related to human social activities within urban environment. For the processing aspect, new algorithms are expected to either accelerate the processing process or better fit machines with super computing capacities.

<p>Demands on the quality and reliability of Volunteered Geographic Information have increased because of its rising popularity. Due to the less controlled data entry, there is a risk that people provide false or inaccurate information to the database. One factor that affects the effect of such updates is the network structure of the database schema, which might reveal the database’s robustness against different kinds of false updates. Therefore, network analyses are needed. The aim is to analyse GIS data models, stored in UML class diagrams, for scale-free and small-world properties. Moreover, a robustness analysis is to be carried out on selected data models in order to find out their error and attack tolerance against, for example, false updates. Three graphs were specified from the UML class diagrams: (1) <em>class graphs</em>: classes as nodes and their interactive relationships as connections; (2) <em>attribute graphs</em>: classes and attributes as nodes, with connections between the classes and their attributes; and (3) <em>schema graphs</em>: attributes as nodes and their interactive relationships inside and outside the tables as links. The analysed class diagrams were stored in XMI, and therefore transformed with XSLT to the Pajek network format. Thereafter, small-world and scale-free analyses as well as a robustness analysis were performed on the graphs. </p><p>The results from the scale-free analyses showed no strict power-laws. Nevertheless, the classes’ relationships and attributes, and the betweenness in the schema graphs were long-tailed distributed. Furthermore, the schema graphs had small-world properties, and the analysed class and schema graphs were robust against errors but fragile against attacks. In a network structure perspective, these results indicate that false updates on random tables of a database should usually do little harm, but falsely updating the most central cells or tables may cause big damage. Consequently, it may be necessary to monitor and constrain sensitive cells and tables in order to protect them from attacks</p>

Advances in information and communication technology and the ready availability of Global Positioning Systems (GPS) have made it possible for citizens to create information on the internet expressing their personal perceptions in the form of pictures, videos and text narratives associated with geographic locations. The term Volunteered Geographic information (VGI) was coined to describe the processes whereby non-professionals or “citizen scientists” participate directly in spatial data creation, editing and shared use. VGI offers promise as an innovative way for members of the public to participate directly in the use, production and sharing of spatial information that is relevant to issues of personal or community concern and as a means of addressing some of the issues associated with traditional public participation methods. Planners can find meaning in the heterogeneous, time-sensitive, geo-social geographic information created by citizen volunteers in a bottom-up participation process where planners give up some control over what data is collected and from whom. However, uncertainties associated with volunteered geographic information include relevance, credibility, representativeness and quality of the geographic information. This thesis investigates the opportunities and barriers to the use of volunteered geographic information as public participation in planning. A framework and methodology for collaborative quality control of VGI through multi-criteria subjective relevance ratings of the VGI by its producers and users is put forward in this thesis. The relevance rating framework for quality control of VGI is based on the use of relevance in information retrieval in information science to improve the relevance of search engine results. This concept is transferred to the quality control of VGI contributions to determine the best VGI contributions to be used in planning as public participation. A VGI web application prototype, including the subjective relevance rating system, was created and a methodology and demonstration of its use for public participation was presented.

The field of crime mapping has an extensive history, yet it has managed to remain an effective tool for policing even in modern times. This success can be attributed in part to the field’s willingness to adapt to newer technologies as they have become available. A current trend that is occurring internationally is the practice of online crime mapping. Many police services from around the world have recognized the importance of using the Internet to connect with the public that they serve. To this end, while most police services have an online presence in the form of a Web site, some have opted to go further and to publish their crime data spatially in the form of an interactive Web-based mapping application. Presently, the City of Toronto has opted not to engage in interactive Web mapping and has limited their online publications to only static maps and written crime reports. This thesis attempts to build upon the capabilities that are offered by Web GIS tools for crime mapping applications in the City of Toronto. To achieve this, two Web applications were developed to help facilitate the process of reporting crime incidents and gang-related graffiti. The services in these Web applications were developed using ArcGIS for Desktop 10.1 and hosted using ArcGIS for Server 10.1, while the Web applications themselves were developed using the ArcGIS API for JavaScript. Each application was designed to support interactive incident mapping, as well as anonymous incident reporting. In addition, the Graffiti Tagger application utilized a mobile-themed interface and image attachments to promote on-the-go graffiti incident reporting. By doing this, it was hypothesized that the overall quality and quantity of data contributed to the Toronto Police Service would increase. To test this hypothesis, a survey was developed and released to a number of participants with varying backgrounds and technical skill levels. The results of this survey showed that a public desire did exist for both of these Web applications, along with a willingness from the majority of participants to voluntarily participate in using these applications. These results suggest that adopting the use of Web mapping applications has the potential to increase the quantity, and potentially the quality, of crime data that is reported.

Demands on the quality and reliability of Volunteered Geographic Information have increased because of its rising popularity. Due to the less controlled data entry, there is a risk that people provide false or inaccurate information to the database. One factor that affects the effect of such updates is the network structure of the database schema, which might reveal the database’s robustness against different kinds of false updates. Therefore, network analyses are needed. The aim is to analyse GIS data models, stored in UML class diagrams, for scale-free and small-world properties. Moreover, a robustness analysis is to be carried out on selected data models in order to find out their error and attack tolerance against, for example, false updates. Three graphs were specified from the UML class diagrams: (1) class graphs: classes as nodes and their interactive relationships as connections; (2) attribute graphs: classes and attributes as nodes, with connections between the classes and their attributes; and (3) schema graphs: attributes as nodes and their interactive relationships inside and outside the tables as links. The analysed class diagrams were stored in XMI, and therefore transformed with XSLT to the Pajek network format. Thereafter, small-world and scale-free analyses as well as a robustness analysis were performed on the graphs.  The results from the scale-free analyses showed no strict power-laws. Nevertheless, the classes’ relationships and attributes, and the betweenness in the schema graphs were long-tailed distributed. Furthermore, the schema graphs had small-world properties, and the analysed class and schema graphs were robust against errors but fragile against attacks. In a network structure perspective, these results indicate that false updates on random tables of a database should usually do little harm, but falsely updating the most central cells or tables may cause big damage. Consequently, it may be necessary to monitor and constrain sensitive cells and tables in order to protect them from attacks

In recent years Crowdsourced, or Volunteered, Geographic Information (CGI, VGI), has emerged as a large, up-to-date and easily accessible data source. Primarily attributable to the rise of the Geoweb and widespread use of location enabled technologies, this environment of widespread innovation has repositioned the role of consumers of spatial information. Collaborative and participatory web environments have led to a democratisation of the global mapping process, and resulted in a paradigm shift to the consumer of geographic data also acting as a data producer. With such a large and diverse group of participants actively mapping the globe, the resulting flood of information has become increasingly attractive to authoritative mapping agencies, in order to augment their own spatial data supply chains. The use of CGI would allow these agencies to undertake continuous improvement of their own data and products, adding a dimension of currency that has previously been unattainable due to high associated costs. CGI, however, through its diversity of authorship, presents a quality assurance risk to these agencies should it be included in their authoritative products. Until now, this risk has been insurmountable, with CGI remaining a “Pandora’s Box” which many agencies are reluctant to open. This research presents an algorithmic model that overcomes these issues, by quantifying trust in CGI in order to assess its implied quality. Labeled “VGTrust”, this model assesses information about a data author, its spatial trust, as well as its temporal trust, in order to produce an overall metric that is easy to understand and interpret. The VGTrust model will allow mapping agencies to harness CGI to augment existing datasets, or create new ones, thereby facilitating a targeted quality assurance process and minimizing risk to authoritativeness. This research proposes VGTrust in theory, on the basis of existing examinations of trust issues with CGI. Furthermore, a facilitated case study, “Building Our Footprints” is presented, where VGTrust is deployed to facilitate the capture of a building footprint dataset, the results of which revealing the veracity of the model as a measure to assess trust for these data. Finally, a data structure is proposed in the form of a “geo-molecule”, which allows the full spectrum of trust indicators to be stored a data structure at feature level, allowing the transitivity of this information to travel with each feature following creation. By overcoming the trust issues inherent in CGI, this research will allow the integration of crowdsourced and authoritative data, thereby leveraging the power of the crowd for productive and innovative re-use.