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Programming tools and algorithms for hexagonal rasters was the first thing I ever did resembling research. It was the topic of my MSc thesis, and while a MSc at the time was much closer to modern day PhD, hexagons took me well beyond it. An application to hydrography resulted in my first peer-reviewed publications, that still gets cited now an then.

During my stint at EAWAG I applied hexagonal rasters yet again, then to flood modelling. A new suite of tools and accompanying literature emerged from that work that has kept evolving since. Further tools and publications remain in the offing, much to the drive of the Urban Water Systems department at EAWAG.

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The presentation below outlines some of the peculiarities and advantages of hexagons that make them so fascinating.

Beyond their advantages in partitioning the Euclidian space, hexagons are also a useful to partition the rounded surface of the Earth. I keep interest open on this specific topic through the application of Discrete Global Grid Systems (DGGS) to raster modelling.


  • HexASCII - specification of a file format for hexagonal rasters.

  • hex-utils - tools to create and use hexagonal rasters with the HexASCII format.

  • hex-utils-qgis - QGis plug-in to use HexASCII rasters.

  • hex-utils-grass - GRASS plug-in for HExASCII rasters (unfinished).

Selected Literature

  • L. M. de Sousa, J. P. Leitão. Hex-utils: A Tool Set Supporting HexASCII Hexagonal rasters. Proceedings of the 3rd International Conference on Geographical Information Systems Theory, Applications and Management: GISTAM, 1, 177-183, 2017.

  • L. M. de Sousa, J. P. Leitão. HexASCII: A file format for cartographical hexagonal rasters. Transactions in GIS, 00:116, 2017

  • J.P. Leitão, L. M. de Sousa, M. J. Gibson, A. S. Chen, D. A. Savić. Hexagonal cellular automata for flood modelling. Proceedings of CAMUSS, 2016.

  • L. M. de Sousa, F. Nery, R. Sousa and J. Matos, Grelhas Geodésicas Globais, V Congresso Nacional de Cartografia e Geodesia, Abril 2007.

  • L. M. de Sousa, F. Néry, R. Sousa and J. Matos, Assessing the accuracy of hexagonal versus square tilled grids in preserving DEM surface flow directions, 7th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences, July 2006.