Claire Ellul

Assessing Data Completeness of VGI through an Automated Matching Procedure for Linear Data

New, free and fast growing spatial data sources have appeared online, based on VolunteeredGeographic Information (VGI). OpenStreetMap (OSM) is maybe the most representative project of this trend. Its increasing popularity and density urges researchers on studying its data quality. When this includes comparison with a reference dataset, data matching is necessary for the comparison to be meaningful, usually performed manually at data preparation stage. We propose an automated matching method specifically designed for VGI, based on a multi-stage approach that combines geometric and attribute constraints. We apply it on OSM dataset to compare it against official data from Ordnance Survey. We then show how the results can be used to evaluate data completeness of OSM.

Requirements for topology in 3D GIS

Topology and its various benefits are well understood within the context of 2D Geographical Information Systems. However, requirements in three-dimensional (3D) applications have yet to be defined, with factors such as lack of users’ familiarity with the potential of such systems impeding this process. In this paper, we identify and review a number of requirements for topology in 3D applications. The review utilises existing topological frameworks and data models as a starting point. Three key areas were studied for the purposes of requirements identification, namely existing 2D topological systems, requirements for visualisation in 3D and requirements for 3D analysis supported by topology. This was followed by analysis of application areas such as earth sciences and urban modelling which are traditionally associated with GIS, as well as others including medical, biological and chemical science. Requirements for topological functionality in 3D were then grouped and categorised. The paper concludes by suggesting that these requirements can be used as a basis for the implementation of topology in 3D. It is the aim of this review to serve as a focus for further discussion and identification of additional applications that would benefit from 3D topology.

Investigating approaches to improving rendering performance of 3D city models on mobile devices

Three-dimensional (3D) city models have uses including on-site validation of utility infrastructure, support for augmented reality, personalized tourist information, real estate sales, and 3D pedestrian navigation. Increasingly, such applications are deployed on mobile devices, whose use is becoming more prevalent. Tablet devices are used for more professional use requiring larger screens, mobile phones for more casual users. However, many 3D city models contain hundreds of buildings, which in turn results in performance issues when attempting to visualize such models on these devices. Two issues can be identified as contributory factors – the lower specification of the mobile device itself when compared with desktop machines and the lower bandwidth network between the device and the server (3G mobile or Wi-Fi). Both of these can be addressed by reducing the volume of data in the model. To achieve this, we generalize a 2D data-set (using aggregation and simplification) and then extrude the generalized 2D maps to 3D. This minimizes the number of buildings to be transmitted over the network and processed by the on-board graphics engine. To additionally address the bandwidth issue, we make use of topological data structuring to build and transmit a minimal description for each building. Combining these approaches, we compare the results obtained for generalized and un-generalized data-sets, on a tablet and mobile device. A performance increase of between 7 and 9 times is observed.

A Preliminary Investigation into the Challenges of Learning GIS in Interdisciplinary Research

A geographic information system (GIS) can be a valuable research tool, helping scientists understand location and bridge the gaps between subjects in interdisciplinary research (IDR), which has been promoted for its real-world solutions. However, a GIS can be difficult to use and may require understanding of a number of concepts as well as tools and technology. This complexity is compounded by additional challenges commonly encountered in IDR. This paper examines some of the challenges facing learners of GIS in IDR projects, with a particular focus on the appropriateness of current teaching methods in this context.

Mapping social vulnerability to flood hazard in Norfolk, England

In this paper, we present a method to assess social vulnerability through the creation of an Open Source Vulnerability Index (OS-VI). The OS-VI provides context to environmental hazards and allows NGOs and local agencies to better tailor services and provide targeted pre-emptive vulnerability reduction and resilience-building programmes. A deductive indicator-based approach is utilised to incorporate a wide range of vulnerability indicators known to influence vulnerability. Unlike many vulnerability indices, the OS-VI incorporates flood risk as well as the loss of capabilities and the importance of key services (health facilities and food stores) through the measurement of accessibility when determining an areas level of social vulnerability. The index was developed using open-source mapping and analysis software and is composed completely of open-source data from national data sets. The OS-VI was designed at the national level, with data for all proxy indicators available across the entirety of England and Wales. For this paper, a case study is presented concerned with one English county, Norfolk. Highlights We produce an open-source vulnerability index. Accessibility to health care found to be severely affected by flooding. High vulnerability areas found to be disproportionately impacted by flooding. Urban extent of an area found to increase its level of vulnerability. Flood affected areas more likely to be composed of elderly, sick and poor.

A Platform for Location Based App Development for Citizen Science and Community Mapping

Community Mapping and Citizen Science involve members of the public in projects to address real-world problems such as noise pollution, air pollution or large-scale development in their neighbourhood. Many of these are inherently location-based and maps provide a powerful tool for engagement. Most importantly, they can be tailor-made to display information required by the drivers of these projects—different groups of people with different interests. Previous Community Mapping and Citizen Science projects allowed the public to capture data for use on such maps via web based systems. However, mobile devices offer additional means of data capture and their in-built sensing devices (microphone, accelerometer, GPS) allow participants to work with additional types of information not available on web-based systems. Although many such Applications (Apps) exist, our experience with community groups shows that flexibility is key—the groups themselves must be able to decide what information they are interested in. While it is possible to meet this need by developing a bespoke App for each group, many of the group members involved in such projects are not programmers and do not have funding for bespoke development. This paper describes the development of a location based services App platform for Community Mapping and Citizen Science. The platform allows an unlimited number of bespoke Apps to be created by a non-technical administrator, without the need for programming skills.

Can topological pre-culling of faces improve rendering performance of city models in google earth?

3D City Models are becoming more prevalent, and have many applications including city walk-throughs or fly-throughs to show what a new building would look like in situ, or whether a view or light will be blocked by a new structure, flood modeling, satellite and signal modeling. Often, these models are created using a process of extrusion of 2D topographic mapping, resulting in Level of Detail 1 buildings with flat roofs. The models can contain many thousands of polyhedra, which in turn results in performance issues when attempting to visualize such models in virtual earth applications such as Google Earth. This paper presents the results of a series of tests to determine whether using a topological approach to pre-cull hidden Faces from the model can bring about performance improvements. Such an approach could also be said to be one step towards the generalization of such models to support multiple levels of detail.

Geography and Geographical Information Science: interdisciplinary integrators

Academic research projects provide a unique opportunity to analyse and solve the problems of society, such as the challenges of hunger and healthcare resulting from population growth and migration in a world where resources are finite. More and more, real world problems cannot be defined within a single discipline – “geography problem”, “chemistry problem”, “civil engineering problem” – they are complex and multi-faceted and “ . . . resist understanding or resolution when approached from single disciplines” (Golding, 2009, p. 2). To understand how Geography and Geographical Information Science (GIS) can contribute to Interdisciplinary Research (IDR), it is relevant to articulate the differences between the different types of such research. “Multidisciplinary” researchers work in a “parallel play” mode, completing work in their disciplinary work streams and exchanging outputs as and when needed. This will ultimately result in separate publications by participants from each discipline and fosters a loose continued connection between researchers (Aboelela et al., 2007). “Interdisciplinary” research is described in language from all disciplines involved. Data and analytical methods are also more mixed, requiring researchers fromone discipline to learn, at least in part, aboutmethodologies from the others in order to complete their work. Publications are shared and language will be established that is intelligible to all involved fields (Aboelela et al., 2007). Examining the above, Geography and GIS fit very well into the multidisciplinary context. They can contribute tools, methods and techniques to problems, while permitting researchers to work within their own discipline. For example, in a multidisciplinary project to create GPS-enabled portable, personal air quality sensors, the electronics engineers creating the sensor board perhaps do not need to understand the way the resulting data will be mapped and analysed, and both aspects of the project can be written up in discipline specific-journals. Transforming the sensor project from multidisciplinary to interdisciplinary requires further integration. This involves a dialogue between the sensor team and the mapping team as to the appropriate frequency of data capture, to resolve the conflict between the limitations of the sensor devices and battery and the requirement for as dense a dataset as possible. A common dialogue also needs to be established with regard to sensor and positional errors and how they are mapped and communicated to end users of the data. All researchers need to understand the basics of mapping and interpolation, and of the calibration process of the sensors.

Towards a Property Registry 3D Model in Portugal: Preliminary Case Study Implementation Tests

The 3D concept emerged as a key concept within geoinformation science. 3D geoinformation has been proved to be feasible and its added value over 2D geoinformation is widely acknowledged by researchers from various fields. Even so, 3D concept merits still need to be exploited further and more specific applications and associate products are needed—such as within property cadastre, our ultimate field of interest. The growing densification of urban land-use is consequently increasing situations of vertical stratification of rights. Traditional 2D cadastral models are not able to fully handle spatial information on those ownership rights in the third dimension, thus 3D cadastre has been attracting researchers to better register and spatially represent real world overlapping situations. A centralised distributed cadastral management system, implementing a 2D cadastral model, has been conceived by the national cadastral agency in Portugal: the so-called SiNErGIC. The authors seek to show that there is room though for further investigation on the suitability of a 3D modelling approach, incorporating both topological-geometric representation and legal/administrative components, capable of handling the overall multipurpose cadastral reality in Portugal. This paper focuses primarily on the clear identification of some case studies illustrating the pertinence of such an approach; first technical implementation tests were carried out.

Making metadata usable in a multi-national research setting

SECOA (Solutions for Environmental Contrasts in Coastal Areas) is a multi-national research project examining the effects of human mobility on urban settlements in fragile coastal environments. This paper describes the setting up of a SECOA metadata repository for non-specialist researchers such as environmental scientists and tourism experts. Conflicting usability requirements of two groups - metadata creators and metadata users - are identified along with associated limitations of current metadata standards. A description is given of a configurable metadata system designed to grow as the project evolves. This work is of relevance for similar projects such as INSPIRE.