On most large projects, an auditor or a lender's monitoring team visits the site once or twice and relies on the contractor's and the engineer's certification for everything in between. The gap between physical progress and certified progress is where excess and irregular payment lives. Imagery closes part of that gap without a site visit for every check.
How the comparison works
A sequence of satellite passes, drone footage, and geotagged site photographs is aligned to the project schedule and to the progress claimed in each running-account bill. Sentinel-class satellite imagery is enough to track site-level progress — earthworks, foundations, superstructure floors, roads laid. Higher-resolution commercial imagery and drone footage give building-level detail. The output is an independent estimate of where the project actually is, set against where the bills say it is.
When imagery is not enough
Imagery has limits, and a defensible audit acknowledges them:
- Optical satellite passes are blocked by cloud and by dense tree cover. Where that happens, the check falls back to drone footage, geotagged photographs, and radar imagery.
- Dense urban sites need higher-resolution commercial imagery and photo verification rather than 10-metre satellite tiles.
- Interior finishing, MEP works, and anything below ground are not visible from above and still need physical inspection.
The right role for imagery is triage: it tells the team which projects and which bills need a physical inspection, and it gives the inspector an evidence pack before they travel.
Backing it with measurement and material checks
Imagery-based progress verification works alongside the document-side tests:
- A risk-based selection of bill items is independently re-measured against the Measurement Book.
- Consumption of key materials — steel, cement — implied by the bills is reconciled against the theoretical requirement from the drawings and standard coefficients.
- Quality and third-party test records are checked for the specified frequency.
Where certified progress runs ahead of what the imagery and re-measurement support, the finding is specific: the bill, the item, the quantity, and the estimated over-certification, with the imagery dates attached.
Fitting it into the audit
None of this replaces the auditor's judgement or the final measurement. It changes which projects get a site visit, sharpens the questions asked when the inspector gets there, and gives the audit an independent basis for the progress position rather than relying solely on the certification under review. Data residency matters here too — bills, contracts, drawings, and imagery stay inside the audit body's own infrastructure.
Get the Capital Project Audit Readiness Guide
The full document set, running-account bill and measurement tests, the procurement file review with bidder-collusion indicators, imagery-based progress verification, and a printable pre-audit checklist.
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