Calculate Volumes

You can use WebODM Lightning's cloud interface to calculate the volume between a base surface and a digital surface model (DSM). Both cut (above the base) and fill (below the base) volumes are supported.

note

A DSM must be available for the tool to work. You can generate a DSM by either selecting the Volume Analysis preset when processing a task or by making sure the dsm option is turned on.

Create a Volume Measurement

1. Click the View Map button

2. From the toolbar, select the "Measure volume, area and length" tool

3. Start placing points to define the base plane, then click "Finish measurement"

A dialog box will appear. Calculation of the volume can take a few seconds to a few minutes, depending on the size of the area and the resolution of the DSM. After processing is complete, the results will be displayed. The base surface method can be changed.

Base Surface

The definition of the base surface can be calculated using one of several methods, listed below:

Method	Description	Best When	Default
Triangulate	Points are triangulated and a surface is linearly interpolated from the results of the triangulation	Bounds of the stockpile are visible and surface is mostly flat	✔️
Plane	Fits a plane that is minimally distant from all points	Bounds of the stockpile are visible and surface is hard (e.g. cement), sloped or flat
Average	A plane with height set to the average height of all points	The surface is relatively flat, but with some variation (averaging helps smooth out variation)
Highest	A plane with height set to the maximum height of all points	Calculating fill volumes of containers or enclosures (e.g. swimming pools)
Lowest	A plane with height set to the minimum height of all points	Bounds of the stockpile are not visible (e.g. hidden by a wall)

Exporting Results

Press the Export to GeoJSON button to export the volume calculation in GeoJSON format.

Accuracy

With proper data capture, GCPs and when GSD is ~1 cm / pixel, the expected accuracy should be within 1-2%.

Field Planning

The use of Ground Control Points is recommended as well as following all guidelines for creating successful maps with a target GSD of 1 cm / pixel.

For the flight pattern, stockpile measurement tasks typically do not require a crosshatch pattern or an angled gimbal, due to the natural inclines of stockpile materials. Only in certain cases, such as when erosion creates steep angles on the stockpile, would a crosshatch flight pattern and angled gimbal improve results.