ICC Programming

Analysis for Thematic Mapping

7114.1 - Data Classification for Highlighting Polygons with Local Extreme Values in Choropleth Maps

Friday, July 7
8:30 AM - 8:50 AM
Location: Balcony A

Following the general demand for a task-oriented concept in map design, in this paper one specific task will be treated in detail: the preservation and highlighting of local extreme values in choropleth maps. Polygons with local extreme values are ones that show a larger (local maximum) or smaller (local minimum) attribute value compared to all directly neighboring polygons. For a visual identification in a classified choropleth map, such a polygon must belong to a class other than the surrounding polygons. However, data classification methods that are commonly used in the process of generating choropleth maps are data-driven, i.e., the intervals are determined solely on the basis of the present frequency distribution of the original values. With such a division along the number line, the spatial context of the underlying data is completely neglected and with that the desired categorization for local extreme values is not guaranteed. As a consequence, a new method (called PLEX) will be presented for this purpose. The application and the effectiveness of this method will be demonstrated using real-world examples.

Jochen Schiewe

Professor
HafenCity University Hamburg

Jochen Schiewe is Professor for Geoinformatics and Geovisualization at HafenCity University Hamburg, Germany.He is Vice-President of the German Cartographic Association (DGfK), Chair of the DGfK Commission on "Cartography and Research" as well as Chair of the ICA conference series "GeoViz_Hamburg" in 2011, 2013 and 2015. His research focus is on modeling and visualization of uncertainties, usability of maps, and cartographic algorithms.

Presentation(s):

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Peter Schmitz

Principal Researcher
CSIR Built Environment

Dr Peter Schmitz holds a PhD in Geography and a BSc (Hons) degree in Geoinformatics and works ate the CSIR in South Africa. He is active in geospatial analysis and forensic geography. He is also active in logistics specialising in supply chains for the military and spatial data as well as in forensic geoscience. He has been part of the CSIR team that did the election-night forecasting at national and local municipal elections since 1999.He is currently the commission chair of the ICA Commission on Map Production and Geoinformation Management.

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