The Douglas-Peucker line simplification algorithm : an introduction with programs

CISRG discussion paper ;

Cartographic Algorithms: Problems of Implementation and Evaluation and the Impact of Digitising Errors

Cartographic generalisation remains one of the outstanding challenges in digital cartography and Geographical Information Systems (GIS). It is generally assumed that computerisation will lead to the removal of spurious variability introduced by the subjective decisions of individual cartographers. This paper demonstrates through an in‐depth study of a line simplification algorithm that computerisation introduces its own sources of variability. The algorithm, referred to as the Douglas‐Peucker algorithm in cartographic literature, has been widely used in image processing, pattern recognition and GIS for some 20 years. An analysis of this algorithm and study of some implementations in wide use identify the presence of variability resulting from the subjective decisions of software implementors. Spurious variability in software complicates the processes of evaluation and comparison of alternative algorithms for cartographic tasks. No doubt, variability in implementation could be removed by rigorous study and specification of algorithms. Such future work must address the presence of digitising error in cartographic data. Our analysis suggests that it would be difficult to adapt the Douglas‐Peucker algorithm to cope with digitising error without altering the method. Copyright © 1991, Wiley Blackwell. All rights reserve

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

CISRG discussion paper ;

Line generalisation by repeated elimination of the smallest area

CISRG discussion paper ; 1

Line generalisation by repeated elimination of points

This paper presents a new approach to line generalisation which uses the concept of ‘effective area’ for progressive simplification of a line by point elimination. Two coastlines are used to compare the performance of this, with that of the widely used Douglas-Peucker, algorithm. The results from the area-based algorithm compare favourably with manual generalisation of the same lines. It is capable of achieving both imperceptible minimal simplifications and caricatural generalisations. By careful selection of cutoff values, it is possible to use the same algorithm for scale-dependent and scale-independent generalisations. More importantly, it offers scope for modelling cartographic lines as consisting of features within features so that their geometric manipulation may be modified by application- and/or user-defined rules and weights. The paper examines the merits and limitations of the algorithm and the opportunities it offers for further research and progress in the field of line generalisation. © 1993 Maney Publishing

A Wii Bit of Fun: A Novel Platform to Deliver Effective Balance Training to Older Adults

BACKGROUND: Falls and fall-related injuries are symptomatic of an aging population. This study aimed to design, develop, and deliver a novel method of balance training, using an interactive game-based system to promote engagement, with the inclusion of older adults at both high and low risk of experiencing a fall.STUDY DESIGN: Eighty-two older adults (65 years of age and older) were recruited from sheltered accommodation and local activity groups. Forty volunteers were randomly selected and received 5 weeks of balance game training (5 males, 35 females; mean, 77.18 ± 6.59 years), whereas the remaining control participants recorded levels of physical activity (20 males, 22 females; mean, 76.62 ± 7.28 years). The effect of balance game training was measured on levels of functional balance and balance confidence in individuals with and without quantifiable balance impairments.RESULTS: Balance game training had a significant effect on levels of functional balance and balance confidence (P Peer reviewedFinal Published versio

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

Commitment to business ethics in UK organizations

Purpose – The purpose of this research is to determine the commitment to business ethics in UK corporations. This study reports on the responses of those organizations that participated in the survey and possessed a code of ethics.Design/methodology/approach – An unsolicited questionnaire was sent to the top 500 private sector organizations by market capitalization in the UK. A total of 92 companies responded, of which 56 possessed a code of ethics.Findings – The empirical findings indicate that the processes involved in developing business ethics commitment have begun to be recognized and acted upon at an organizational level. The supporting measures of business ethics commitment appear to be under-utilized by many of these UK organizations. This suggests that many organizations have not so far developed a strong organizational commitment to embedding their codes of ethics into organizational practices.Research limitations/implications – While the responses provided a rich picture of organizational actions, further research exploring internal culture and attitudes would add to an understanding of organizational commitment.Practical implications – It is found that in order to influence practice, it is not enough to have the artefacts of an ethical culture, such as codes, without ensuring that all employees are assisted in understanding what is required of them.Originality/value – Despite a history of business ethics research, there are a limited number of studies seeking to understand UK companies\u27 commitment to ethical codes. The paper provides guidance on steps that organizations can take to develop a higher level of commitment

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