What does Geospatial mean?The word geospatial is used to indicate any form of data that has a geographic component to it. This means that the records in a dataset have locational information tied to them such as coordinates, addresses or postcodes. In the case of photos or scans from remotely piloted aircraft, they will be tagged with GPS information which will contain location and time markers. The applications are many and varied but include site surveys for the construction industry, environmental work, agriculture, archaeology, mining and quarrying. [caption id="attachment_1705" align="aligncenter" width="555"] A photographic map of farmland[/caption] Of course, the images don't have to be confined to standard photographs. Infra-red, near infra-red, and multi-spectral sensors can be employed to provide more specific results. There's also the option to use lasers and LED sources to collect LiDAR data. [caption id="attachment_1706" align="aligncenter" width="555"] A laser scanned point cloud image of a forest[/caption]
Why use a Drone for Aerial Mapping?The advantage of using a drone over conventional aircraft and satellites is that the image quality will be much more detailed. A satellite image will probably be accurate to more than a metre while an image from a low altitude UAV can be accurate to less than a centimetre - a huge improvement. On some UAVs, the GPS tagging may not be as accurate as is necessary, especially if the aircraft is moving quickly, as in the case of a fixed wing drone. Not all systems are capable of tagging down to the nearest millisecond so that could produce a significant margin for error. However, with some UAVs, the GPS tagging may not be as accurate as is necessary. This is especially true if the aircraft is moving quickly, as in the case of a fixed wing drone. Not all systems are capable of tagging down to the nearest millisecond so that could produce a significant margin for error. One way to make your map more accurate is to use Ground Control Points. GCPs are markers with accurately record GPS coordinates that will be visible from the air. This will help to align the captured images with the site that's being surveyed. [caption id="attachment_1718" align="aligncenter" width="555"] Example of a ground control point[/caption] Where drones are needed to provide pinpoint-accurate positioning for highly detailed missions, then after-market options are available to replace or augment what is often a consumer-grade GPS system. The cost savings over a conventional, fixed-wing aircraft are considerable too, especially if companies hire in professional UAV pilots when they're needed rather than buying their own drones and employing full-time crew.
How Do Surveying Professionals Feel About Drone Mapping?In theory, one or two people can deploy a drone on site and get the data down to a computer or up to the cloud in a matter of minutes. Some professionals in the surveying industry might be worried about the de-skilling of the whole operation but human practitioners would still be needed to ensure there are accurate ground control points on the site and they will certainly be needed to interpret the masses of the data that will be produced. In an article for Land Alliance, authors and experienced researchers Dr Janina Mera and Kevin Barthel had this to say on the subject: "Revolutionary technological advances frequently face the most resistance from the very people in the technical fields that stand the most to gain from the advance. Change generates uncertainty and fear. Fear the 'machines' will supplant the practitioners. It is no surprise, therefore, to see hesitation and reluctance by surveyors and traditional aerial mapping specialists in light of the rapidly increasing use of UAV technology for geospatial data collection. The fear is that with the UAV and the perceived largely automated process, the role of these traditional geospatial professionals will be diminished. This concern is unwarranted."
Utilising the Aerial Mapping DataOnce the data is uploaded to your computer it's all down to the software. A quick Google search will reveal a plethora of options. The two packages that you'll probably see more often than others are Pix4D and DroneDeploy. The appeal of Pix4D for DJI pilots is that the app is already available for the majority of recent DJI Drones. This includes:
- The Inspire 1 Range
- Inspire 2
- Phantom 4
- Phantom 4 Pro & Pro +
- Mavic Pro
- The Matrice 200 Series
- Matrice 600
...Aerial drone mapping is a huge area to cover in just one article so it's something we are bound to come back to in the future. Keep checking back to Heliguy's Insider Blog for more insights into commercial UAV usage and, of course, the latest news from the industry.