Why Measure Stockpiles by Drone
Stock counts at batching plants, recycling yards and construction sites are often based on truck tickets and estimates, then corrected when someone walks the pile with a GNSS rover. Walking a pile is slow, measures only a few dozen points, and puts a person on loose, unstable material next to moving plant.
A drone measures the whole surface of every pile from above in a short flight. Nobody climbs the material, and operations only need to keep plant clear of the piles while we fly. The result is a volume for each pile that you can check against your books every month.
What We Measure
| Material | Typical site | Notes |
|---|---|---|
| Sand and granite aggregate | Concrete batching and precast plants, bulk yards | Monthly stock reconciliation against deliveries and usage |
| Excavated soil and earth | Construction and earthworks sites, holding areas | Track material moved off site or held for reuse |
| Recycled aggregate and C&D material | Recycling and crushing yards | Measure input and output piles separately |
| Scrap and bulk materials | Industrial and recycling yards | Irregular piles are measured as surfaces, not shapes |
How the Volume Is Calculated
- Capture the surface. The drone photographs the whole yard with heavy overlap, and the images are processed into a 3D surface tied to ground control points in SVY21 and Singapore Height Datum.
- Define the base. Each pile needs a base surface. The best base is a survey of the empty ground taken before stockpiling. Without one, we fit a base to the ground around the toe of the pile.
- Calculate the volume. The volume of each pile is the space between its surface and its base, in cubic metres.
- Convert to tonnes. Tonnage is the volume multiplied by the material's bulk density. You supply the density from your records or a lab test, because it varies with material, grading and moisture.
- Compare. On repeat surveys we report the change in each pile since the last flight.
Accuracy, and What the Numbers Are For
On well-defined piles with good ground control, drone volumes typically agree with careful ground surveys to within a few percent, and they are far more consistent from month to month. The biggest source of error is usually the base, not the drone. Piles stacked against walls, sitting in pits, or built up over years on unknown ground are harder to measure, and we flag them in the report.
Be clear about the use. The Singapore Land Authority's Standard and Specifications for Survey Using Unmanned Aerial System in Singapore does not recommend photogrammetry point clouds for volume payment certification. Our drone volumes are for stock control, reconciliation, planning and progress. Where a volume will be used to certify a payment, it should be measured by LiDAR to SLA's 1st-order standard and certified by a Registered Surveyor.
What You Receive
- Volume report — the volume of each pile in cubic metres, with tonnage where you supply bulk densities.
- Orthophoto — a current aerial map of the yard with each pile outlined and numbered.
- 3D surface — the measured surface of the site, for your records or for comparison later.
- Change report — on repeat surveys, the change in each pile since the last flight.
- Spreadsheet — the figures in CSV, ready for your stock or accounting system.
Why Choose SG Drone Inspections
No One on the Piles
Every pile is measured from the air, keeping people off loose material and away from loaders and trucks.
Same Method Every Month
Repeat surveys use the same control and base surfaces, so month-to-month changes are real changes in stock.
CAAS-Permitted Operations
Our flights run under the required CAAS operator and activity permits. We handle the airspace approvals, including near Changi, Paya Lebar and Seletar.
Clear About Limits
We tell you which piles are hard to measure and why, and when a job needs LiDAR and a Registered Surveyor instead.
Stockpile Survey Pricing
Prices cover planning, CAAS permits, ground control, the flight, processing and the volume report. Regular monthly or quarterly surveys are quoted as a programme.
| Site area | Drone capture and processing |
|---|---|
| Under 1 hectare | $1,000 — $1,500 |
| 1 — 5 hectares | $1,500 — $3,000 |
| 5 — 20 hectares | $3,000 — $6,000 |
Measuring whole earthworks rather than piles? See our cut and fill earthwork survey.
Frequently Asked Questions
Get a Stockpile Survey Quote
Send us the site address, the number of piles, the materials and how often you want them measured. We reply with a scope and quote within 24 hours.