HG-J05 Lot 105 · Surveys

Building-change survey from two aerial photos

Every building coded on an older and a recent aerial photo; new, demolished and enlarged buildings flagged in a prioritised findings report for building inspection.

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P-01 Earlier aerial photo of a low-rise neighbourhood

Plan no.: HG-J05
Scale: 1:1,250
Sheet: 05/16
Updated: 11.2026
Client: A local authority
Discipline: Surveys
Data source: Aerial photos 2020/2022 vs 2023 · oblique imagery

A local authority

Project provisions

Challenge

Building additions are hard to spot on patrol: they sit in back yards, on rooftops and behind facades. An inspection department needs a list of places worth checking, not another general patrol.
Solution

We coded every building on two aerial photos from different years and compared them. New buildings, demolished buildings and footprints that grew beyond a threshold agreed with the authority were marked in a change layer. Oblique imagery was used to check added floors, balconies and extensions that cannot be seen from above. Each suspected case got a screenshot, and the findings were compiled in a report by priority.
Outcome

The inspection department goes out with a sorted list and an image for every finding, and can cross-check it against permit records to focus on additions that were never approved.

Legend

Deliverables

Deliverables: Building-change survey from two aerial photos
Key	No.	Deliverable
	105.1	Change layer: new, demolished and enlarged buildings
	105.2	A screenshot for every suspected case
	105.3	Findings report by priority
	105.4	Optional cross-check with building permits