Satellite construction monitoring, explained plainly

Earth-observation satellites photograph the same places repeatedly. By comparing a construction site across observations, you can measure how much its surface is changing over time — and notice when that change unexpectedly slows.

The data

Ground Stasis uses the European Copernicus programme’s Sentinel-2 mission, which images most locations every few days at 10 m–20 m resolution and is free and public. That cadence and resolution are well suited to tracking whether a sizable site is actively changing — and poorly suited to counting individual beams or reading interior work.

Reading change honestly

Spectral indices such as NDVI, NDBI, and BSI summarise vegetation, built-up surfaces, and bare soil. They are indirect signals: useful for detecting that a surface moved, not for proving what specifically happened. A credible monitoring product uses them to flag change for review, not to assert construction milestones.

Clouds and gaps

The biggest honesty test in satellite monitoring is weather. Clouds, haze, and snow routinely make an observation unusable. The right response is to report a data gap — never to treat a missing image as evidence that work stopped.