Volumetric Stockpile Surveys using UAV

Warner Surveys opened a Unmanned Aerial Vehicle (UAV) Department at the end of 2018, bringing on board experienced UAV pilot and manager Adam Tate to the Warner Surveys team. This led to Warner Surveys gaining Civil Aviation Authority (CAA) approval to fly in December and undertaking our first commercial UAV flights at the start of January.

One of the survey types we have been carrying out with UAVs is that of volumetric stockpile surveys. This is the task of measuring the volume of material in a stockpile either as a one off exercise, or, as part of a periodic measurement regime to aid, e.g. monthly payments or material valuation. Traditionally these measurements would have been taken by surveyors on the ground utilising a grid based survey pattern, or, with terrestrially based laser scanners to create a point cloud of the stockpile. The UAV, however, instead of Lidar or a laser scanner, carries a high resolution digital camera and undertakes the survey using photogrammetric techniques.

How does a UAV carry out a survey?

The UAV is programmed to fly a pre-set prepared flight path over the stockpile whilst taking a series of photographs with overlapping fields of view. Following the data collection, the photographs are processed through a photogrammetric software and converted into a 3D model. The volume of the stockpile can then be analysed within the 3D processing software to provide the total volume details.

What are the advantages of using a UAV?

This is a highly accurate survey method as the UAV sees the whole of the stockpile including all of its features, slopes and complex 3D shapes. This could be considered more accurate than a terrestrial survey where it will be difficult to capture the surface of the stockpile with 100% accuracy.

There are also two other key advantages, those of Safety and Time. Utilising a UAV removes surveyors from the stockpile environment itself, therefore removing them completely from the risks that this entails. Speed-wise a UAV can collect a large amount of data very quickly, allowing the survey to be undertaken much faster than a terrestrially based volumetric survey technique.

For more information get in touch with Operations Director, Clif Webb