It’ll come as no surprise, but stockpile measurement and reports account for the most frequent use case for drones on worksites. But how do drones and software actually measure your stockpiles?
Stockpile measurement methods with drone surveying
Before you can take a single measurement of your stockyard, you need to fly your drone to capture site data. There are a few ways to do this. “Drone surveying,” at its core, means using a drone to take aerial photos of your site and some form of GPS and ground control to tie the images down.
With recent technological advancements, there are two major workflows to get the job done: GCP-based drone surveying and PPK drone surveying.
Drone surveying with traditional ground control
For this workflow, you need a sufficient number of known points to verify and pin your drone imagery to the ground.
Having multiple GCPs on your site when surveying ensures 1/10 foot accuracy or below, but they can be time consuming to set up on a large worksite. There are a couple ways to set up traditional ground control:
- Known-point method. A surveyor has to physically walk your site, shoot the points with a rover, and mark them for visibility.
- Using AeroPoints. AeroPoints are smart GCPS you drop in an optimal distribution across the entire surveyed area.
As recently as a few years ago, the planning, risk assessment, and legwork associated with setting up ground control has been a necessary, if unwanted, sacrifice.
Onboard GPS correctional processing changes the need for ground control
PPK drones are able to accurately geotag and correct their GPS data. (If you want to learn more about RTK, check out our Drone Surveying Explained: From GCPs to PPK ebook.)
PPK stands for “post-processing kinematic.” With PPK capability, the drone geotags X, Y, and Z coordinates to each images based on its GPS unit. While this is happening, a base (be it a base station, an AeroPoint, or the CORS network) on the ground is also recording positional information, but with much more accurate triangulation.
After the flight is completed, those two sets of GPS data are matched up using a timestamp, which is recorded when the drone takes a picture. Now that we know the offset after the fact, the initial, less-than-accurate on-board GPS data is then overwritten, giving precise geotags for the imagery.
How stockpile volume measurements works
Ideally, a stockpile would be a shape with an easy volume to calculate, like a perfect cube or cone. But even in good cases, stockpiles are irregular.
What makes surveying stockpiles with a drone different is that it can capture all those irregularities and faithfully renders them in your survey, thus allowing the computer to calculate the volume of the true shape, not a rough approximation.
This accuracy starts with the imagery. Unsurprisingly, drone photos capture significantly more detail than shooting points with a rover. Photos let you see the physical details between the individual points.
Both horizontally and vertically (Z values), drones are able to capture and render higher resolution data, that’s just as accurate as traditional surveying. Correctly used, drones in conjunction with ground control can produce 3D surveys with 20–50mm accuracy.
Stockpile reports using measurement software
No matter how often you report out on your stockpiles, you want to be able to pull those reports without much hassle, and get them in the file formats you need.
While some services are ultra-specific when it comes to stockpile reporting, those usually charge you by the pile. Often they don’t even return visuals, just a report that includes numbers.
But cloud-based drone data platforms like Propeller typically charge per dataset, which, of course, isn’t limited to stockpiles alone. You can survey your whole site for that price and get back an interactive, visual 3D survey.
Better financial forecasting
When it comes down to it, drone surveying and data platforms like Propeller allow you to accurately measure your stockpiles.
The benefits of that trickle down to even the smallest parts of your operations. Having that accurate information on hand, and shareable, lets you do better financial forecasting. No more “fluff factor” in your inventory reporting.
Tighter supply-chain management
Knowing what you actually have on your site also allows you to tighten up supply-chain management.
See when you need more stock and how much. If you’re your own supplier, you can plan out when you need to start drilling and blasting. If you use an external supplier you can plan out purchases and budget better. Don’t be surprised by a big order again.
See how much your inventory is worth
And with material property calculators built in, all the reporting you already need to complete can now show you the actual dollar value of your piles—or the money sitting in your whole stockyard. See just how much your inventory is worth with every single survey.
Want to learn more about stockpile measurement and reporting? Download our new guide to Stockpile Measurement and Reports with Drone Surveying.