Stockpile volumes that survive an audit

Your volume number will eventually be argued with — by a customer, an auditor, or your own finance team. Here is how to make it defensible before that happens.

A stockpile volume is not a mapping output. It is a number that ends up in an inventory valuation, on an invoice, or in a dispute. The day someone challenges it, "the software said so" is not an answer.

Four things decide whether your number holds up. None of them is which software you bought.

1. The base surface is the whole argument

A volume is the space between a surface and a base. Get the surface right and the base wrong and you have a confident, precise, wrong answer. The three common bases:

If you are billing off the number, fly the pad before material lands on it. One extra flight, once, removes the entire class of dispute.

2. Draw the toe where the material actually stops

Most volume error is not photogrammetry error, it is boundary error. A toe drawn a metre out on a 40-metre pile moves the answer by more than any accuracy claim on any vendor's page. Zoom in. Follow the material, not the shadow.

3. Ground control decides whether you can compare months

Within a single map, drone GPS is enough: relative measurement is good to roughly one to three times your ground sample distance. But the moment you compare this month against last month, both models need to sit in the same place on Earth — and on GPS alone each of them floats independently by metres.

That is how a site "gains" 400 cubic metres nobody moved. Place control, survey it once, and reuse it on every flight of that site.

4. The software should refuse when the data is thin

This is the part nobody sells and everybody needs. If a pile is half-occluded, if the mesh is not closed, if the surface has holes where the material is, the honest output is not a number. It is a refusal that says which data was missing.

A tool that always returns something is not being helpful. It is moving the risk onto you, quietly, and you will only find out when someone checks.

A short checklist

Why we built it this way

DroneGrid returns volumes with the base surface, cell count and boundary recorded alongside them, and it declines to answer when the data cannot carry the answer — with the reason attached. That is unusual, and it is deliberate: a number you cannot defend is worth less than no number at all.

Two flights are free if you want to point it at a pile you already know the answer to. That is genuinely the best way to judge it.