The Visvalingam algorithm: metrics, measures and heuristics

This paper provides the background necessary for a clear understanding of forthcoming papers relating to the Visvalingam algorithm for line generalisation, for example on the testing and usage of its implementations. It distinguishes the algorithm from implementation-specific issues to explain why it is possible to get inconsistent but equally valid output from different implementations. By tracing relevant developments within the now-disbanded Cartographic Information Systems Research Group (CISRG) of the University of Hull, it explains why a) a partial metric-driven implementation was, and still is, sufficient for many projects but not for others; b) why the Effective Area (EA) is a measure derived from a metric; c) why this measure (EA) may serve as a heuristic indicator for in-line feature segmentation and model-based generalisation; and, d) how metrics may be combined to change the order of point elimination. The issues discussed in this paper also apply to the use of other metrics. It is hoped that the background and guidance provided in this paper will enable others to participate in further research based on the algorithm

Historical collaborative geocoding

The latest developments in digital have provided large data sets that can increasingly easily be accessed and used. These data sets often contain indirect localisation information, such as historical addresses. Historical geocoding is the process of transforming the indirect localisation information to direct localisation that can be placed on a map, which enables spatial analysis and cross-referencing. Many efficient geocoders exist for current addresses, but they do not deal with the temporal aspect and are based on a strict hierarchy (..., city, street, house number) that is hard or impossible to use with historical data. Indeed historical data are full of uncertainties (temporal aspect, semantic aspect, spatial precision, confidence in historical source, ...) that can not be resolved, as there is no way to go back in time to check. We propose an open source, open data, extensible solution for geocoding that is based on the building of gazetteers composed of geohistorical objects extracted from historical topographical maps. Once the gazetteers are available, geocoding an historical address is a matter of finding the geohistorical object in the gazetteers that is the best match to the historical address. The matching criteriae are customisable and include several dimensions (fuzzy semantic, fuzzy temporal, scale, spatial precision ...). As the goal is to facilitate historical work, we also propose web-based user interfaces that help geocode (one address or batch mode) and display over current or historical topographical maps, so that they can be checked and collaboratively edited. The system is tested on Paris city for the 19-20th centuries, shows high returns rate and is fast enough to be used interactively.Comment: WORKING PAPE

Spatiotemporal data as the foundation of an archaeological stratigraphy extraction and management system

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Designing for the dichotomy of immersion in location based games

The interaction design of mixed reality location based games typically focuses upon the digital content of the mobile screen, as this is characteristically the primary navigational tool players use to traverse the game space. This emphasis on the digital over the physical means the opportunity for player immersion in mixed reality games is often limited to the single (digital) dimension. This research seeks to redress this imbalance, which is caused, in part, by the requirement for the player?s attention to be systematically switched between the two worlds, defined in this research as the ?Dichotomy of Immersion?. Using different design strategies we propose minimising the reliance of the player upon the mobile screen by encouraging greater observation of their physical surroundings. Using a ?research through design? approach for the mixed reality game PAC-LAN: Zombie Apocalypse, we illustrate design strategies for increasing immersion in location based games, which we believe will aid designers in enabling players to more readily engage with the physical context of the game and thus facilitate richer game experiences

Problems of Designing Geoportal Interfaces

The manuscript is devoted to analysis of the problem of designing graphical geoportal interfaces. The support points for the problem solutions are formulated and rationale of each of them is given. The emphasis was placed on the following orientations: to a flexible process of interface development, the need to introduce adaptability, progressive development, the motivated abandonment of geospatial content management systems and the use of third-party libraries where necessary, problem-solving and achieving goals. The lists of basic functional and qualitative requirements for graphical geoportal interfaces are given. In the last segment, the authors share their experience in the development of geoportal solutions

Discourse Phenomena as a Window to the Interfaces

This paper examines the two lines of analysis that are generally pursued when dealing with discourse phenomena in the generative tradition: syntactico-centric and interface-based approaches. Syntactico-centric analyses are criticized because they need construction-specific mechanisms, while interface-based analyses sometimes challenge standard assumptions about the architecture of grammar. The discussion is mainly theoretical, but three case studies serve as exemplification: focalization, ellipsis and parentheticals. The second part of the paper is focused on parentheticals; a brief proposal is presented regarding the distinction between free and anchored parentheticals from a syntax-phonology interface perspective. The general conclusion is that following an interface-based perspective to approach discourse phenomena can help us gain new insights about the nature of the interfaces and their role in grammar.Aquest article examina les dues línies de recerca que se segueixen generalment quan s'estudien fenòmens discursius en la tradició generativista: enfocaments sintàctico-cèntrics i d'interfície. Critiquem les propostes sintàctico-cèntriques perquè necessiten fer ús de mecanismes específics per analitzar cada construcció en qüestió, mentre que les propostes d'interfície de vegades posen en dubte l'arquitectura gramatical estàndard. La discussió és fonamentalment teòrica, però s'utilitzen tres casos d'estudi: la focalització, l'el·lipsi i els parentètics. La segona part de l'article se centra en els parentètics; es presenta una proposta bàsica per formalitzar les diferències entre parentètics lliures i ancorats (ang. free i anchored) des d'una perspectiva d'interfície sintaxi-fonologia. La conclusió general és que seguir una línia d'anàlisi d'interfície per tractar els fenòmens discursius pot ajudar-nos a comprendre millor la naturalesa de les interfícies i el seu paper a la gramàtica