Uber H3 has revolutionized spatial indexing, but its cell sizes vary a lot, i.e. its cells aren’t equal-area, skewing global analyses and visualizations. What if you could have H3’s elegant hierarchical indexing and true equal-area cells for statistically sound results? We introduce IGEO7, an aperture 7 hexagonal equal-area DGGS with its hierarchical indexing system Z7. See how you no longer have to choose between handy hexagon indexing and statistically sound analysis with open-source world.
Hexagonal Discrete Global Grid Systems (DGGS) offer significant advantages for spatial analysis due to their uniform cell shapes and efficient indexing. Among the three central place apertures (3, 4, and 7), aperture 7 subdivisions exhibit very desirable properties, including the preservation of hexagonal symmetry and the formation of unambiguous indexing hierarchies. Interest in hierarchically indexed aperture 7 hexagonal DGGS has recently increased due to the popularity of the H3 DGGS. But there are currently no open-source equal-area aperture 7 hexagonal DGGS available, that provide similar indexing capabilities like H3. We present IGEO7, a novel pure aperture 7 hexagonal DGGS, and Z7, its associated hierarchical integer indexing system. In contrast to H3, where cell sizes vary by up to ±50% across the globe*, IGEO7 uses cells of equal area, making it a true equal-area DGGS. IGEO7 and Z7 are implemented in the open-source software DGGRID. We also present a use case for on-demand suitability modeling to demonstrate a practical application of this new DGGS.
If you use IGEO7, please cite us. Also, if find it relevant for your work or research, please reach out.
Kmoch, A., Sahr, K., Chan, W. T., and Uuemaa, E.: IGEO7: A new hierarchically indexed hexagonal equal-area discrete global grid system, AGILE GIScience Ser., 6, 32, https://doi.org/10.5194/agile-giss-6-32-2025, 2025.
Presented by Alexander Kmoch on 19 November 2025 16:00, at FOSS4G 2025 Auckland.
This video provides a deep dive into the IGEO7 system, explaining its advantages over H3 and how it integrates with Python tools like dggrid4py.
Expanding the Ecosystem: IGEO7 Support
IGEO7 is now implemented in the open-source software DGGRID and has a handy Python wrapper, dggrid4py. IGEO7 uses the ISEA7H base system and added the special Z7 index onto it. The DGGAL library implements a compatible system, called ISEA7H_Z7.
- DGGRID: DGGRID is a command-line application designed to generate and manipulate icosahedral discrete global grids, IGEO7 preset.
- dggrid4py: A Python wrapper to configure and run the foundational DGGRID software, please read.
- DGGAL: DGGAL, the Discrete Global Grid Abstraction Library.
- GeoPlegma: This project aims to be central open-source project developing software implementing or using Discrete Global Grid Systems (DGGS).
