Drone mapping? Yes, of course drones can capture high-quality images from the air, but – mapping…?
Yes, it’s available. Yes, it’s accurate. And yes, it’s cost-effective. Provided, of course, that your drone pilot has the right equipment, the right software, and the right skill set. Because even the best pilot can’t achieve the accuracy that mapping demands without a little help.
So how does it work?
To create a really accurate map, the images from the drone must be as detailed as possible. Everything depends on the Ground Sampling Distance or GSD – the distance between the centre of two consecutive pixels measured on the ground. So the ideal setup is a top-quality camera mounted on a drone flying as close to the ground as circumstances (and safety) permit. Of course, that means it will take longer to complete the survey than flying at a higher level. And that, in turn, means more individual flights. Because even the best batteries only last so long!
But even the best images won’t be enough if the flight pattern isn’t carefully (and very accurately) controlled. Which is where the programming comes in…
Take a program like Pix4Dcapture, for instance. It allows you to pre-program a drone flight to achieve the desired flight path, image overlap, flight speed and camera angle. During the flight, its ‘map view’ allows you to see where the drone is, its altitude and its flight speed. Or you can switch to the live feed from the camera.
Afterwards you can review the images you’ve captured on-site – and reshoot if necessary. And once you’re satisfied, those images can be uploaded to the cloud for processing into maps. Or even 3D models.
Relative and absolute accuracy
So far, so good. This should give you good relative accuracy – meaning that every element of the site will be accurately placed on the map. But you may also need good absolute accuracy. And that calls for precise GPS coordinates for key points on your map. (Otherwise, to quote an extreme example, your coastal site may appear to be underwater…!) By pegging your results to these Ground Control Points you can achieve the absolute accuracy that the best mapping demands.
And, as always, quality software is your friend. Mapsmadeeasy, for example, provides an online georeferencing interface which ensures your area map can be overlaid, precisely, in Geographic Information (GIS) Systems or Google Earth.
Quality drone mapping demands pixel-perfect accuracy – which only a high-resolution camera can deliver. It takes a powerful drone to carry that camera. And it takes a skilled operator, using quality software, to plan and execute a survey that will produce the results you need.
At Birds-i-images we do that on a regular basis. So if you’d like to know more, why not give us a call on 07971 519729 or drop us an email?