A mine survey is useful when the next person can act on it. For a survey team, that may mean releasing a checked surface to planning. For an operations manager, it may mean understanding why a stockpile figure differs from last month's report. Drone imagery can support both tasks, provided the measurement assumptions remain visible throughout the workflow.
This guide focuses on camera-based photogrammetry at surface mines and quarries. It explains how to use periodic surveys for stockpile measurement, terrain change and information handover, and where other evidence is needed.
Start with the report your operation needs
Decide who will use the survey and what they need to know before choosing an output. An orthomosaic provides a georeferenced view of visible site features. A surface model or point cloud adds elevation information for geometric analysis. A visually convincing 3D model alone is not an acceptance test.
For inventory reporting, identify the stockpiles, measurement boundaries and baseline. For mine planning, agree on the surveyed area and the surface the planning team expects to receive. For periodic operational reviews, select dates that correspond to the reporting period and record any activity between capture and review.
Useful questions include:
- What material volume lies within this boundary and above this reference surface?
- Where has the mapped surface changed since the previous accepted survey?
- Which working areas and access routes need an updated visual record?
- Which parts of the site could not be adequately captured?
Answering these questions makes the deliverable easier to review than a collection of files without a stated purpose.
Make stockpile quantities traceable
Stockpile volume depends on more than the visible shape of the pile. The selected boundary and base surface are part of the calculation. Where a pile covers uneven ground, an assumed flat base can produce a different quantity from a surveyed pre-stockpile surface. The camera cannot observe the ground concealed beneath the material.
Give each stockpile a stable identifier. Record its capture date, boundary, base choice and any excluded areas. Review incomplete reconstruction around edges and obstructions before accepting the measurement. If the method changes between reporting periods, explain the change so that a measurement difference is not mistaken for material movement.
A volume in cubic metres is not a tonnage. Converting volume to mass requires a defensible bulk density for the material and its condition. Moisture, mixed material and changes in packing may require separate assessment. Photogrammetry does not determine ore grade, composition or density from the stockpile's geometry.
Treat survey comparison as a controlled handover
Two surfaces must share compatible horizontal and vertical references, units and coverage before their difference can support an operational decision. Review the survey quality as well as the apparent change. A vertical offset between datasets may look like material added or removed across the whole site.
A BLM mine production verification project, documented by the USGS, used aligned surface models from separate acquisition dates to estimate extracted volume. The relevant principle is a consistent spatial reference; the project's results should not be treated as a universal accuracy or productivity guarantee.
For a reporting cycle, preserve the accepted inputs and record which surface was used in each comparison. Mark unobserved areas as gaps. Where trucks or loaders moved material after capture, use the operations record to explain the timing difference. A survey is a dated observation, not a continuous inventory feed.
Set acceptance criteria before processing
Define the required evidence with the survey team. Ground sampling distance describes image pixel size on the ground. Point density describes the number of reconstructed points in an area. Neither measure alone establishes positional accuracy or the uncertainty of a reported volume.
The USGS guidance on UAS imagery calibration addresses acquisition, calibration and independent checks as parts of geometric quality. Use those principles to ask how the delivered data were verified, rather than accepting a precision claim based only on image resolution.
Inspect coverage and surface reconstruction around steep faces, shadows, water, dust and occluded areas. Distinguish observed geometry from interpolated gaps. If the data cannot support the intended decision, identify what needs to be surveyed again or measured by another suitable method before the report is released.
Keep observation separate from engineering judgement
Remote imagery can help a specialist locate visible changes and prepare a field assessment. It does not establish the stability of a highwall or tailings structure. Geotechnical inspection, instrumentation and the mine's safety procedures remain separate requirements for those decisions.
Coordinate capture with site operations and the people responsible for access and work activities. Observing a feature from a distance may reduce the need for some close approaches, but it does not remove flight hazards or all field work. Record the conditions that limit interpretation and pass them to the people using the survey.
Similarly, a sequence of maps can document visible land disturbance and recovery. Water quality, air quality and environmental compliance require their own evidence. A surface image should not be presented as proof that those conditions are satisfactory.
Know what the sensor can tell you about resources
Terrain mapping can support access planning and the spatial context of exposed geological features. Conventional photographs do not, on their own, identify mineral composition or establish a subsurface resource or reserve.
Specialist exploration surveys use different measurements. For example, USGS work with drone-mounted radiometric instruments helps guide mine-waste sampling and characterisation. That work is distinct from ordinary photogrammetry and is not a capability attributed to Maply here.
Build a repeatable workflow with Maply
Maply's mining workflow brings survey maps, volume measurements and comparisons into a shared environment. The drone mapping software guide explains the processing and analysis steps to evaluate with your team.
Make each handover include the acquisition date, area covered, coordinate reference, measurement assumptions and reviewer. Check file formats and units with the receiving planning or engineering team. Review whether the report answers the original question without requiring its author to reconstruct the calculation verbally.
To assess fit, talk to Maply with a representative survey, your reporting requirements and an example of a current reconciliation issue. Evaluate how the team checks, measures and shares the data before extending the workflow across the operation.
