Stockpile volumes without walking the pile
A drone measures the whole pile surface, not a few dozen shots on its flanks. What decides the number you get is the base surface, the density you apply and how consistently it is done each time.
A surface on top, a surface underneath
A volume is the space between two surfaces. The drone gives you the top one: a dense elevation model of every pile, measured from overlapping photos or LiDAR. The bottom one, the base surface, has to be defined. That choice often moves the answer more than the flight does.
A traditional walk-around survey picks up the toe and a handful of points on the slopes and top, and joins them with triangles. It works on neat conical piles. On irregular piles, piles against walls or piles with bites taken out of them, a drone model captures far more of the real shape and keeps crews off unstable material and away from loaders. Checking by hand is still possible: every report comes with the surfaces, so anyone can repeat the calculation in their own software.
Consistency beats precision for inventory. An auditor cares less about the last cubic metre than about a method applied the same way every period, with the same base, the same boundaries and a density that can be traced. That is what we set up on the first visit and repeat. For how control keeps the vertical honest, see accuracy; for sites that also move earth, see cut and fill.
The output is a report per pile: volume, the base method, the date and time of capture and, if you give us a bulk density, an estimated tonnage. Files come too, so your own team or auditor can check the result.
Four ways to define the bottom of a pile
| Method | How it is built | Good for | Watch for |
|---|---|---|---|
| Triangulated toe | A surface joined across points around the pile's edge | Free-standing piles on firm ground | Uneven ground under the pile is flattened |
| Lowest point plane | A flat plane at the lowest toe elevation | Piles on a level pad | Overstates volume on sloping ground |
| Design or pad surface | The engineered pad or bin floor elevation | Bins, bunkers, paved yards | Needs accurate as-built of the pad |
| Previous survey | The ground surface from an earlier flight before the pile was placed | Long-term piles and fill areas | Needs the earlier flight in the same datum |
Why two volume numbers disagree
Different base methods month to month
Switching from toe to plane, or redrawing the toe differently, changes the volume even if the pile did not move.
Volume treated as tonnage
Bulk density varies with material, moisture and compaction. A volume multiplied by a guessed density is still a guess.
Piles touching or merging
Where two products meet, the boundary is a judgement.
Loaders working during the flight
Material moves between photos and leaves holes or doubled edges.
Uncontrolled vertical error
A small vertical shift across a large pile area adds up to a real volume error.
How a monthly or quarter-end count runs
Set up once
Name the piles and products, agree base methods, and place permanent control marks that survive yard traffic.
Fix the time
Book the flight for the same point in your cycle, such as the last working day of the month.
Fly and process
Same height, overlap and control each visit, so changes are real.
Report
Volume per pile, change since last count, base method and density used, with the orthomosaic showing boundaries.
Reconcile
Your accountant or auditor compares with sales and production records; questions are pinned to the pile on the image.
Who reads the volume report
Controller or accountant
- They need from you
- A defensible inventory figure at period end.
- You need from them
- Densities and the cut-off time.
- On the DroneLink record
- Dated reports in the site record, with each month's version kept.
External auditor
- They need from you
- A repeatable method and evidence.
- You need from them
- Their questions early, before year end.
- On the DroneLink record
- Method notes, files and images shared by link from one record.
Site or yard manager
- They need from you
- Quick numbers for ordering and sales.
- You need from them
- Pile names, access and a quiet window.
- On the DroneLink record
- Comments and approvals on the platform rather than email threads.
Volumes in the browser
Today, volumes arrive as PDF and CSV reports with the underlying surfaces. The DroneLink site viewer, which will let you draw a pile boundary and calculate its volume in the browser and compare flights, is coming. See site viewer. For material sites, read quarries and aggregates.
Questions
How accurate are drone stockpile volumes?
With good control, a consistent base surface and a stable pile, drone volumes are generally regarded as at least as reliable as a ground walk-around survey, because the whole surface is measured. The base surface and density choices usually matter more than the flight.
How do you calculate the volume of a stockpile with a drone?
The drone creates an elevation model of the pile's top surface. A base surface is defined underneath, and software computes the volume between them. The report states which base method was used.
Can a drone measure stockpile tonnage?
A drone measures volume. Tonnage is volume times bulk density, which you supply from scale data or testing. We show the density used so the tonnage can be checked or updated.
How often should stockpiles be measured?
Most operations match counts to their accounting cycle, often monthly or quarterly, plus year-end. Regular counts with the same method make changes easier to trust.
Can you measure piles in a building or under a roof?
Indoor and covered piles need flights without GNSS, or different sensors, and depend on the space. Tell us about the structure and we will say whether it is feasible.
Is it safe to fly over an active yard?
We plan flights to keep clear of people not involved in the operation, coordinate with the yard manager, and prefer breaks or quiet times. Loaders moving during capture also hurt accuracy.
How much does a drone stockpile survey cost?
It depends on site size, number of piles, control, reporting and frequency. Recurring counts are scoped once and repeated. We quote each job and do not publish prices.
Tell us about your site.
An address and what you need is enough to start. We reply with what it will take and when we can fly.