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Publications

Primary IGEO7 Paper​

Cite this

If you use IGEO7 in your research, please cite:

Kmoch, A., Sahr, K., Chan, W.T., Uuemaa, E. (2025). IGEO7: A new hierarchically indexed hexagonal equal-area discrete global grid system. AGILE: GIScience Series, 6, 32. https://doi.org/10.5194/agile-giss-6-32-2025

@article{kmoch2025igeo7,
  title   = {{IGEO7}: A new hierarchically indexed hexagonal
             equal-area discrete global grid system},
  author  = {Kmoch, Alexander and Sahr, Kevin and Chan, Wai Tik
             and Uuemaa, Evelyn},
  journal = {AGILE: GIScience Series},
  volume  = {6},
  pages   = {32},
  year    = {2025},
  doi     = {10.5194/agile-giss-6-32-2025}
}

DGGS Area and Shape Distortions​

Kmoch, A., Vasilyev, I., Virro, H., Uuemaa, E. (2022). Area and Shape Distortions in Open-Source Discrete Global Grid Systems. Big Earth Data. https://doi.org/10.1080/20964471.2022.2094926

Systematic assessment of area and shape distortions across H3, S2, rHEALPix, and other open-source DGGS. Provides the quantitative basis for IGEO7's equal-area motivation.

Central Place Indexing (Z7 Theory)​

Sahr, K. (2019). Central Place Indexing: Hierarchical Linear Indexing Systems for Mixed-Aperture Hexagonal Discrete Global Grid Systems. Cartographica, 54(1), 16–29. https://doi.org/10.3138/cart.54.1.2018-0022

The theoretical foundation for the Z7 indexing system — how hierarchical digit encoding and GBT arithmetic underpin the index.

DGGS Foundations​

Sahr, K., White, D., Kimerling, A.J. (2003). Geodesic Discrete Global Grid Systems. Cartography and Geographic Information Science. https://doi.org/10.1559/152304003100011090

The canonical reference for DGGS design principles: base polyhedra, projections, cell shapes, and refinement strategies.

pydggsapi​

Kmoch, A., Chan, W.T. (2025). pydggsapi: An OGC API DGGS implementation for IGEO7 and other grid systems. FOSS4G 2025.

GBT Neighbour Traversal​

Renoud, W., Shaw, J. (2025). Z7: Exploratory C++ implementation of Z7 neighbourhood traversal. GitHub. https://github.com/wrenoud/Z7/

White, D., Kimerling, J.A., Overton, S.W. (1992). Cartographic and Geometric Components of a Global Sampling Design for Environmental Monitoring. Cartography and Geographic Information Systems, 19(1), 5–22. https://doi.org/10.1559/152304092783786636

van Roessel, J.W. (1988). Conversion of Cartesian coordinates from and to Generalized Balanced Ternary addresses. Photogrammetric Engineering & Remote Sensing, 54(11), 1565–1570.

ISEA Projection​

Snyder, J.P. (1992). An Equal-Area Map Projection for Polyhedral Globes. Cartographica, 29(1), 10–21.