Honorable Mention

A Simple Pipeline for Coherent Grid Maps

Wouter Meulemans, Max Sondag, Bettina Speckmann

View presentation: 2020-10-29T16:15:00Z GMT-0600 Change your timezone on the schedule page
2020-10-29T16:15:00Z
Exemplar figure
Our 3-step pipeline to automatically compute a grid map, illustrated on the Dutch municipalities: (1) decompose the containing shape into parts; (2) compute a tile-based Mosaic Cartogram using these parts; (3) assign elements to tiles per part.
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Direct link to video on YouTube: https://youtu.be/ve7qn0VDyUg

Keywords

Grid maps Algorithms Tile maps Small multiples Geovisualization

Abstract

Grid maps are spatial arrangements of simple tiles (often squares or hexagons), each of which represents a spatial element. They are an established, effective way to show complex data per spatial element, using visual encodings within each tile ranging from simple coloring to nested small-multiples visualizations. An effective grid map is coherent with the underlying geographic space: the tiles maintain the contiguity, neighborhoods and identifiability of the corresponding spatial elements, while the grid map as a whole maintains the global shape of the input. Of particular importance are salient local features of the global shape which need to be represented by tiles assigned to the appropriate spatial elements. State-of-the-art techniques can adequately deal only with simple cases, such as close-to-uniform spatial distributions or global shapes that have few characteristic features. We introduce a simple fully-automated 3-step pipeline for computing coherent grid maps. Each step is a well-studied problem: shape decomposition based on salient features, tile-based Mosaic Cartograms, and point-set matching. Our pipeline is a seamless composition of existing techniques for these problems and results in high-quality grid maps. We provide an implementation, demonstrate the efficacy of our approach on various complex datasets, and compare it to the state-of-the-art.