Stockpile and volumes

Not the sensor. The base.

The surface of a stockpile is easy to measure. The bottom of it is not, because you cannot see it. Whatever assumption you make about the toe and the underlying surface drives more error than any difference between capture methods.

Second problem is repeatability. A volume on its own means little. A volume compared to last month means everything, and that comparison only works if both surveys used the same base, the same coordinate system and the same toe definition.

Third is access. Active pads have loaders on them. Covered sheds have no sky view. Neither is a good place to walk with a GPS rover.

Define the base surface once and reuse it. Survey it properly when the pad is empty, then compare against it every time. Redefining the base each survey is the most common source of unexplainable variance.

Fly open yards with RTK. Consistent altitude, consistent overlap, same flight plan each cycle. Repeatability comes from doing the same thing.

Walk covered stockpiles. No sky view means no aerial option, and a handheld scanner captures the full surface including the parts against a wall.

Capture the toe carefully whichever method you use. Get low, get angles, make sure the break line is real rather than interpolated.

Use the same toe definition every cycle and write it down.

The dividing line is a roof. Everything under one is a walking job.

Both capture methods land in a similar range for open stockpiles, so the choice is about access rather than accuracy.

The dominant error is the base surface and the toe break, not the sensor. A survey with a perfect surface and a guessed base is less trustworthy than a rougher survey against a properly measured base.

For repeatability, hold three things constant: the coordinate system, the base surface, and the toe definition. Change any one of them and your month-on-month comparison stops meaning anything.

Where the volume goes into a financial reconciliation, verify with independent check shots on the surface and document the base.

A volume figure, a surface, and a comparison against the previous cycle. Often a plan showing the pile extents and a note of the method.

Recipients are usually site managers, quarry managers or finance, so the number matters more than the cloud. Give them the cloud anyway, because the first question after a surprising number is always how it was measured.

What causes trouble: an unexplained variance against last cycle, and a base surface nobody can point to.

Changing the base surface between cycles and not telling anyone. The volume moves, nobody can explain why, and confidence in the whole process goes with it.

The other one is a toe break that was interpolated rather than measured. It looks fine in the surface and it moves the volume by more than most people expect.

And on covered stockpiles, the section against the back wall that nobody could get an angle on. It gets extrapolated, and extrapolated volume is guessed volume.