We tried two different methods of measuring stockpiles and compared their results. We found that making fairly "tight" polygons around the stockpiles yielded more reliable results.
We made 20 attempts at measuring the same stockpile. As a rule of thumb, if we made the points close to the stockpile (a "tight" measurement), we'd get results close to 2,900 cubic meters. If we were much more generous with the room around the stockpile (a "loose" measurement), it would be closer to 3,000 cubic meters.
Examples
"Tight" measurement:
"Loose" measurement:
Recommendations
Be consistent when drawing boundaries
Decide how you are going to use the Volume tool (for example, are you going to take "tight" or "loose" measurements), and then consistently use that method. You'll see from the chart that when separate averages for "tight" and "loose" are calculated, the average variation falls to 0.8% and 1.6%, respectively. This means that if you use a similar method across stockpile measurements, even though you might get a slightly different result each time, the results will be close to a 1% margin of error from the "actual" size.
A tighter boundary is often best
We would recommend that a "tighter" method is better, although not too tight, that the points are actually on the edge of the stockpile—this would cause the surface to be altered using that point and drastically skew the result (see below).
Especially when it is difficult to tell the shape of the stockpile visually, it can help to turn on the Elevation overlay from the menu before making the measurement, as it can show the stockpile more clearly.
The takeaway is that as long as you've done your homework in the data-capture phase and are using a consistent measuring approach, you can be confident in the results.
I still can't do it!
We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.
If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.
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