Volume measurement with DroneDeploy is an extremely fast, accurate and cost-effective method to analyze volumes on your maps from any device. User tests have found that when following best practices DroneDeploy's volume measurements are accurate within 1-2% of traditional ground-based laser measurements.
Below we'll walk you through best practices for how to use the volumetric tool, what the calculations mean, and how to provide feedback.
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In order to define a volume to measure, you first need to select an area for which to compute the volume.
- Choose the
Volumeicon from the
Annotation & Measurementoptions:
The tools in the lower right allow you to undo, or complete your polygon.
- Add points around the stockpile for which you want to compute the volume.
Click or tap to add points to complete the polygon.
- Adjust the points until you are happy with the area of interest. Here is an example result:
Example volumetric calculation. Units can be displayed in the Metric or Imperial system.
- Using the cross arrows in the middle, you can shift the area of interest in order to automatically recalculate the result.
Move the polygon using the cross arrows in the middle.
Choosing the appropriate base plane will help you ensure you are recording accurate measurements.
There are three base-plane options available for volume calculation, Linear Fit, Lowest Point and Triangulated.
Linear Fit (formerly "Best Fit") defines the base plane by fitting a perfectly flat plane, in 3D, through the chosen edge points. It's great for stand-alone stockpiles in most situations on flat ground.
Lowest Point calculates a horizontal base plane from the lowest edge point. This option is more suited to calculate the volume of benches or stockpiles on flat ground in bins, or where there are neighboring piles right up against each other.
Triangulated joins up all of the edge points to create a 3D surface under your stockpile. This is perfect for long thin stockpiles, or for large stockpiles over 0.5 acres in size.
Take note of where you click
As you'll see in the following section - the volume is calculated by creating a surface which fits within the area you define. This means that the elevation of the points you select is very important. For example, accidentally selecting a point on a pile of rocks, as opposed to on the ground, will change the volume calculation and its accuracy.
Sometimes it can be difficult to see the base of a stockpile when looking at the Orthomosaic, due to shadows or similarly colored surrounding areas. To more easily see the nuances in the terrain we recommend using the Elevation Toolbox as the base layer of the map when computing volumes.
Below is an example that demonstrates why using the Elevation Toolbox is a best practice when calculating volumes. In the Orthomosaic (on the left) it is difficult to see the small pile of rocks to the left of the stockpile. Defining the base layer on top of the small rock pile would lead to inaccurate volume calculations. Using the Elevation Toolbox (on the right), the small pile becomes easily viewable, enabling you to avoid defining a point of the base on top of the rocks.
Notice the pile to the left of the main stockpile which is nearly invisible in the orthomosaic. Here, the Elevation Toolbox is useful when defining perimeters.
The volume calculations between the base-plane and the terrain surface of your area of interest is given in terms of the volume that would need to be removed (in the case of a stockpile) and/or added (in the case of a hole) in order to flatten the surface so that it's the same as the surrounding ground.
Cut refers to the volume you would have to remove from the area (a pile) in order to flatten it (e.g., you're cutting off the pile).
Fill corresponds to the volume you would have to haul in, to "fill" a hole, in order to flatten the area.
Cut and Fill volumes are automatically shown on the map when calculating volumes. The actual Volume measurement calculation is Volume = Cut - Fill.
Within DroneDeploy's App Market, you can download the "GCP Volume Analysis" app to see how the volume of your stockpile has changed over time. Simply download the app and then conduct a volume measurement around your stockpile. DroneDeploy will then look for stockpiles in the same area of previous maps that you've flown and show you the Cut, Fill and Volume measurements of that pile. You can even download the data as a CSV file.
Analyzing stockpiles on several maps using GCP Volume Analysis app.
Do Ground Control Points need to be used?
Adding GCP is an effective way to increase accuracy on a global level. However, the data you are getting from a standard drone flight without GCPs will produce highly accurate volume calculations as those measurements are at the local level. When following best practices, these measurements are typically 98-99% accurate so GCPs are not necessarily needed.