Metraipolis › archive › dc_57a030bbaff3

AlphaEarth distinguishes cities but compresses urban variation — arXiv:2609.30356

Source: arXiv (en)
Original: https://arxiv.org/abs/2609.30356
License (as archived): CC0-1.0
Archived: 2026-10-08T03:12:25.942Z
SHA-256 of the archived text: d9b988eb82d66880f29803fa5b237d2e01ac61a7473427a6a529085d0fe8e255
Stable URL of this page: https://metraipolis.com/documento/dc_57a030bbaff3

How to cite

AlphaEarth distinguishes cities but compresses urban variation — arXiv:2609.30356 — arXiv (en), https://arxiv.org/abs/2609.30356 (CC0-1.0); archived copy: https://metraipolis.com/documento/dc_57a030bbaff3 (Metraipolis archive dc_57a030bbaff3, sha256 d9b988eb82d66880f29803fa5b237d2e01ac61a7473427a6a529085d0fe8e255)

BibTeX

@misc{dc57a030bbaff3,
  title = {AlphaEarth distinguishes cities but compresses urban variation — arXiv:2609.30356},
  howpublished = {arXiv (en)},
  url = {https://arxiv.org/abs/2609.30356},
  note = {License CC0-1.0; archived copy https://metraipolis.com/documento/dc_57a030bbaff3; sha256 d9b988eb82d66880f29803fa5b237d2e01ac61a7473427a6a529085d0fe8e255},
  year = {2026}
}

Archived text

Reproduced under CC0-1.0. Attribution: arXiv (en), https://arxiv.org/abs/2609.30356. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

Cities differ in built form, land cover and development history, complicating comparison across places and time. Satellite foundation models map Earth's surface onto common numerical representations. Yet the tasks and targets used to shape them typically do not focus on cities: globally consistent labels for urban function do not exist, and many datasets - especially land cover and land use classifications - collapse the built environment into few classes. Here we audit the representation, focusing on AlphaEarth but with broader applicability to other Earth embeddings, by probing the geometry and geography of embeddings for 1,000 urban areas in 162 countries. We find that cities occupy a shifted but overlapping region on the hypersphere, 62.7° from the global mean direction, and continent and climate predict 24.3% of variation among the mean directions of urban centres in excluded countries. Inside cities, degrees of urbanisation carry 8.9% of the variation, and what they leave holds shared directions whose local orientation varies, not one universal axis of urbanisation. Retained variation is itself unequal: dispersion within urban centres is 14.1% greater per standard deviation of national development, even after adjusting for population, land area and continent. Further controls suggest cities in developing countries present less contrast in vegetation and texture, and dispersion follows that contrast: full adjustment for it leaves at most 6.4% of the gradient. Annually, a city's representation moves nearly eight times more than redrawing its own pixels explains, and contracts where the 2022 loss of Sentinel-1B removed a pass direction. AlphaEarth's representations therefore support comparison across regions, while the differences between its annual layers are not yet validated for comparison over time.

Tema degli esploratori: statistica e scienza dei dati (retro-catalogo arXiv: annunci del 2026-09-28 in cs.CV).
Categorie arXiv: Computer Vision and Pattern Recognition (cs.CV) ; Physics and Society (physics.soc-ph).
Pagina del lavoro: https://arxiv.org/abs/2609.30356 — autori e testo completo sono lì (qui omessi i nomi: nessun dato personale nel deposito).
Licenza: titolo e abstract sono metadati arXiv distribuiti in CC0 1.0; il testo completo ha la licenza scelta dagli autori, indicata sulla pagina.
Letto il 2026-10-08T02:50:19.004Z dalla pagina https://arxiv.org/catchup/cs.CV/2026-09-28?abs=True (consentita dal robots.txt di arxiv.org, con il suo crawl-delay).