Aerial images can document coverage and change, but a polished map or video can conceal missing frames, uncertain coordinates and processing choices. Start with the factual question and the lawful flight plan, then keep flight records, native files and derived products linked. CASA’s advice to people hiring drone operators explains that registration, accreditation, licensing and approvals depend on the operation; credentials alone do not authorise every flight. CASA: hiring a drone operator.
Plan the operation and the evidence together
Specify the site boundary, permitted access, question, required coverage, target features, control points if measurement is contemplated, and what ground records will be needed. Ask the operator to explain the aircraft registration, pilot/accreditation pathway, operator certificate and airspace approval applicable to this flight. Check conditions and expiry dates, not only a credential number. Record weather, light and safety limits likely to affect the result. CASA says commercial drones must be registered and some operations need specific authorisations. CASA registration requirements; CASA operator checks.
Record capture, gaps and transfer
Keep a flight record with operator, aircraft/camera identifier, date, time zone, site reference, flight segment, planned versus achieved coverage, interruptions and known clock or positioning issues. Link each card or file batch to that flight record. On receipt, note sender, recipient, time, method, file count and secure destination. Retain native photographs/video and relevant flight logs; work on separate copies. NIST’s preservation guidance recommends documenting source, transfers, storage and integrity checks for digital images and files. NIST IR 8387.
Handover record — hypothetical example
- Flight F02, western roof, 9 October 2026, 10:15–10:32 AEDT; aircraft D-4 and camera C-4.
- Card M-7 contained 86 JPEG images and one native video. Operator A copied it to the restricted project store at 12:04 AEDT; reviewer B checked count and recorded SHA-256 values in manifest F02-M1.
- Southern parapet was not captured because the flight ended for wind. The orthomosaic therefore has no complete coverage of that edge.
A matching hash can support byte-for-byte continuity of a file, but does not prove the depicted location or the accuracy of a derived measurement. If a comparison fails, investigate handling and processing rather than assuming misconduct. NIST IR 8387, section 3.2.
Describe every derived product
Identify the source files and software behind an edited clip, orthomosaic, geospatial overlay or 3D model. Record crop, colour or stabilisation steps; coordinate reference system, control points and accuracy checks where relevant; and excluded or rejected frames. Display an overlay as an interpretation unless its registration has been validated. Do not use apparent pixel detail as a survey measurement. Engage a surveyor, engineer or imaging specialist if accuracy, causation or alteration is contested.
Repeat visits: a comparison worksheet
Record visit dates/time zones; camera and lens; planned viewpoints and achieved overlap; weather/light; temporary obstructions; site changes that could affect perspective; ground control and site diary references; and the exact proposition supported. Hypothetical example: two flights show a stockpile present Monday and absent Friday. They establish its visible status at those visits, assuming the scene is correctly identified, but not the day of removal, volume moved or responsibility. Test those against weighbridge records, access logs and site diaries. State the gap plainly.
For each exhibit, can a reviewer trace the image or model back to native files, the flight, the operator and the transfer record? Can they see excluded coverage and uncertainty? If not, the visual product is useful for orientation but may be too weak for the proposed factual or technical conclusion.