Example studies

What a map of the past can answer.

We classify old satellite film into buildings, roads, trees and water, then compare it with modern land cover. These four examples show the kinds of questions that opens up. See also our mining, forest and coast studies.

Buildings
Roads
Trees (Panama only)
Water
Other land

01 / Urban growth

Doha: how fast did a desert town become a city?

In 1966 this part of Doha was scattered compounds and tracks. Today it is almost entirely built up, and the main road in the old image is still there.

1966 film of scattered compounds and tracks — 1966 film

Classified buildings and roads in 1966 — Classified

The same area in 2026, fully built up — 2026

20–50×growth in built land across 54 sample areas, from about 1–4 km² in 1966 to 69 km² in 2021

Useful forUrban planning, infrastructure demand and long-term growth modelling

02 / Coastal change

Shanghai: where did the new land come from?

The old film shows open water and mudflats beyond the sea wall. Much of that area is now land, on the edge of today's Pudong airport.

Historical film of the Shanghai coast with open water — 1970s–80s film

Classified water and land on the old coast — Classified

The same area in 2025 with new land and airport facilities — 2025

5.3 km²of the 7.4 km² of water in this 15 km² view was land by 2021. Across 60 sample areas the figure is about 26–33 km²

Useful forReclamation history, ground-stability screening, coastal flood risk and port planning

03 / Forest baselines

Panama: stable totals can hide a big swap.

In the sample, forest area hardly changed between 1966 and 2021. But forest was lost in some places and gained in others. These two views, about 12 km apart, went opposite ways.

Forest with clearings in 1966 — Cleared area, 1966

The same area in 2026, now largely suburban — 2026: now suburbs

The same area in 2026, still forest — 2026: still forest

48–54 → 55 km²forest across 62 sample areas in 1966 and 2021, with about 10 km² lost and 12–16 km² gained

Useful forCarbon project baselines, restoration planning and biodiversity studies that need forest age

04 / Settlement history

Delhi: the villages the city swallowed.

Around 1977 this village stood among fields. Today it is hidden inside continuous city, but its footprint can still be traced. We found 285 outlying settlements like it across the scene.

A village among fields around 1977 — About 1977 film

Classified village, roads and fields — Classified

The same area in 2026, all built up — 2026

65%of the 285 settlements now have built land on at least half of their surroundings. For 34%, it is at least three-quarters

Useful forHousing and land-rights research, public-health studies, heritage records and planning

How to read these numbers

The classifications are automated and have not been checked in the field. They suit screening and exploration. A commissioned study would validate them first.
Doha, Shanghai and Panama figures cover sample areas, not whole cities. Delhi settlement figures cover the full 976 km² scene.
The old maps were simplified to a 10 m grid to match the modern map. Ranges show how the result changes with the rule used.
Delhi's date is an estimate from mission records, and Shanghai's date has not been confirmed yet.
Tides and water levels can shift shorelines between images, so coastal figures are approximate.

Sources

Historical imagery: U.S. Geological Survey declassified archive.
Modern land cover: © ESA WorldCover project 2021. Contains modified Copernicus Sentinel data (2021) processed by the ESA WorldCover consortium.
Modern pictures: contains modified Copernicus Sentinel data 2025–2026.

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