Line generalisation by repeated elimination of the smallest area

CISRG discussion paper ; 1

Cartographic algorithms : problems of implementation and evaluation and the impact of digitising errors

CISRG discussion paper ;

The Douglas-Peucker algorithm for line simplification : re-evaluation through visualisation

CISRG discussion paper ;

A network-based approach for estimating pedestrian journey-time exposure to air pollution

Individual exposure to air pollution depends not only upon pollution concentrations in the surrounding environment, but also on the volume of air inhaled, which is determined by an individual’s physiology and activity level. This study focuses on journey-time exposure, using network analysis in a GIS environment to identify pedestrian routes between multiple origins and destinations throughout the city of Lancaster, North West England. For each segment of a detailed footpath network, exposure was calculated accounting for PM2.5 concentrations (estimated using an atmospheric dispersion model) and respiratory minute volume (varying between individuals and with slope). For each of the routes generated the cumulative exposure to PM2.5 was estimated, allowing for easy comparison between multiple routes. Significant variations in exposure were found between routes depending on their geography, as well as in response to variations in background concentrations and meteorology between days. Differences in physiological characteristics such as age or weight were also seen to impact journey-time exposure considerably. In addition to assessing exposure for a given route, the approach was used to identify alternative routes that minimised journey-time exposure. Exposure reduction potential varied considerably between days, with even subtle shifts in route location, such as to the opposite side of the road, showing significant benefits. The method presented is both flexible and scalable, allowing for the interactions between physiology, activity level, pollution concentration and journey duration to be explored. In enabling physiology and activity level to be integrated into exposure calculations a more comprehensive estimate of journey-time exposure can be made, which has potential to provide more realistic inputs for epidemiological studies

MODELLING LOW EXPOSURE ROUTES IN URBAN MICRO-ENVIRONMENTS

This paper describes how modelled estimates of air pollution can be used within a GIS to derive typical and optimal estimates of journey-time exposure. It also explores the concept of personal exposure reduction and considers the extent to which mobile devices will support the selection of more informed routes through the provision of location-specific data on pollutant concentrations

Development and application of a "spray-can" tool for fuzzy geographical analysis

Most information generated by the general public, particularly for the purpose of decision-support, will inherently contain a spatial component. This spatial data can comprise a very valuable resource for researchers, planners and decision makers, and may be collected for analysis using a Public Participation GIS (PPGIS). The imprecise and abstract nature of the thoughts, feelings and opinions of the public do not, however, lend themselves well to the discrete boundaries enforced by ‘traditional’ GIS data constructs (points, lines and polygons), and as such require data structures that allow for the ‘fuzzy’ nature of these data to be incorporated into their capture, storage and analysis. This paper therefore presents a web-based PPGIS platform with a ‘spray-can’ interface for the capture of fuzzy spatial data; and a relational ‘multi-point-and-attribute’ data structure, which reflects the fuzzy nature of the data, whilst supporting flexible spatial and attribute querying. Whilst the idea of the spray-can interface is not itself novel, the platform demonstrated in this paper has the potential to improve the decision-making process in a number of different areas at a variety of different scales. This is achieved by both increasing levels of interaction with the public through the familiar and user-friendly spray-can interface; and increasing the level of understanding of the spatial and aspatial information that participants contribute, by maximising the potential analytical approaches that may be taken

Visualizing patterns in spatially ambiguous point data

As technologies permitting both the creation and retrieval of data containing spatial information continue to develop, so do the number of visualisations using such data. This spatial information will often comprise a place-name that may be ‘geocoded’ into coordinates, and displayed on a map, frequently using a ‘heatmap-style’ visualisation to reveal patterns in the data. Across a dataset, however, there is often ambiguity in the geographic scale to which a place-name refers (country, county, town, street etc.), and attempts to simultaneously map data at a multitude of different scales will result in the formation of ‘false hotspots’ within the map. These form at the centres of administrative areas (countries, counties, towns etc.) and introduce erroneous patterns into the dataset whilst obscuring real ones, resulting in misleading visualisations of the patterns in the dataset. This paper therefore proposes a new algorithm to intelligently redistribute data that would otherwise contribute to these ‘false hotspots’, removing them to locations that likely reflect real-world patterns at a homogenous scale, and so allow more representative visualisations to be created, without the negative effects of ‘false hotspots’ resulting from multi-scale data. This technique demonstrated on a sample dataset taken from Twitter, and validated against the ‘geotagged’ portion of the same dataset

Evaluating the spraycan:understanding participant interaction with a PPGIS

Whilst widely accepted as an important facet of software design, the evaluation of PPGIS usability is often overlooked in research. This work comprises a novel approach to the evaluation of the Spraycan PPGIS, whereby rich insights into participant behaviour are drawn from data that are natively collected by the platform as opposed to through additional questionnaires, log files or similar. The approach will be validated against a ‘traditional’ questionnaire, before conclusions are drawn relating to the usability of the Spraycan as a platform for the collection of vague spatial data, in the hope of developing a greater understanding into the way in which people interact with geographic problems

Towards the integration of urban planning and biodiversity conservation through collaboration

Despite aspirations to halt biodiversity loss by 2020 under the Aichi Biodiversity Targets, urban development continues to negatively impact UK wildlife and habitats. Reasons behind continued biodiversity decline are examined through the use of semi-structured interviews with ecologists, statutory regulators and land developers.. It is found that despite strict legislation and best practice, for both planning and ecology, there is still much room for subjectivity regarding the protection of specific ecological features and the implementation of the mitigation hierarchy. Interviews also revealed that such subjectivity often facilitates the prioritisation of commercial over ecological benefits during site design. Furthermore, many felt an over reliance on the protection of individual animals, as opposed to maintaining functional connectivity for conservation of wider populations was detrimental to both the development industry and ecology. Our findings support the case for further research into the development of innovative geographical information systems to allow spatial deliberation, and collaborative decision-making between the three stakeholder groups

AIR POLLUTION IMPACTS AND SOURCES UNDER A CHANGING CLIMATE: A CASE STUDY FOR SCUNTHORPE, UK

Climate change may affect local air quality by altering the emission, dispersion, chemical transformation and deposition of air pollutants. This study evaluates the effects of climate change in a real-life mixed land-use situation where there are adjacent urban and industrial activities and also fugitive emissions from stockpiles and unpaved roads. For this example we show how windspeed and time-of-day dependent ‘bi-polar plots’ created from ambient monitoring data can be used to learn more about the nature of sources responsible for exceedances of particulate matter air quality standards, and hence to assess how sensitive their impacts are to climate change. Unpaved roads and wind-blown fugitive sources such as stockpiles and coal handling beds in the industrial area appear to contribute substantially to raised air-quality impacts. The effect of climate change on impacts from these sources may differ from its effect on impacts from conventional combustion sources