Drones Part II – Results
Wow! Drones can collect surprisingly accurate data. I’ll save you from a discussion of the technical details, but the bottom line is that drones clearly have a place in data collection. With surveyed ground control factored in, the drone collected imagery with approximately 2” horizontal and 4” vertical accuracy.
So how does that compare to a traditional, ground-based topographic survey? A traditional topographic survey of the test area produced horizontal and vertical accuracies of 1” and 1.75” respectively. The table below summarizes the differences between the two methods.
While the data collected by a drone are not yet accurate enough for a typical road or site design project, they are quite good. The basic imagery collected without ground control points would work just fine for a planning project, but the GCPs are necessary for any engineering design. A drone would also be a good option when time is limited. As the table above shows, data can be collected very quickly with a drone.
However, it’s important to remember the limitations of drones. Our test area was well-suited for a drone because 1) it was a very open area, and 2) the area was only 40 acres. The weather was also in our favor and we collected the data in a single session on the first try. If the weather had been windy we would have had to postpone until conditions improved.
In this test we used a commercial-off-the-shelf 12MP camera and drone. A camera with more megapixels could collect higher resolution imagery, and therefore improve our accuracy.
Our test area was also away from any public airports, which are no-fly zones for drones without prior approval through a Certificate of Authorization (COA). Getting an approved COA for operating near an airport can be a lengthy process.
PDC will continue to monitor the state of drone technology and identify any opportunities to use drones in our workflow. We now have a surveyor on staff that is an FAA-certificated Remote Airman – stay tuned for a future post about the FAA Part 107 regulations regarding the use of unmanned aircraft.