Categories
Imagery

Basics of Drone flight

How to Capture Drone Imagery

How to capture some cool drone imagery with a few pro tips.

Step one: Get a drone

My personal favorite at the moment is the Maverick Air. It’s tiny and fits easily into a day pack.

Step two: Flight planning

Before you set out to collect imagery it is critical to think about what photogrammetric products you want to derive. This is not a definitive guide but just the bare necessities to get out and have a practice.

What kind of photogrammetric products are you wanting to derive? For me

  • Orthos
  • Point clouds
  • Textured mesh

Getting Ready

In theory prep should look like this. But in reality you end up with cables and wires going everywhere. As a practical point you’re going to be heading out somewhere to collect the imagery, make sure you’ve charged your controller and drone batteries. As a practical point you should really have spare batteries. Flight time on a Mavic Pro for me has been approximately 17 minutes each time I’ve flown.

Think about your flight area

Regulation around drone tech is in flux right now. Check the local regulations. Here in Switzerland it’s still quite free but DO NOT FLY NEAR ANY AIRPORTS. If you didn’t hear about the drone closing down Heathrow airport I would recommend googling it. The Dji no fly zone is quite good for airports.

I’m not sure about New Zealand right now but in Switzerland we have also a national map of flight restriction zones here. It’s also a really good idea to have a quick google on street view to make sure there are no obstacles such as power lines or buildings etc. In the future it really looks like ‘out of line of sight’ will be legal with proper flight planning. Japan just announced its licensing system and France is leading the way.

Phone Data

You’re going to be using basemaps on the phone, data is a really good idea. I’ve had the situation where I’ve crossed into France for data collection but didn’t have a data plan. The GPS still works fine but without a pre-downloaded basemap I was planning the mission blind while on site. Here are some of the outputs from that mission. There is a dam and I missed a tiny bit of the target on the Northern side.

Pro tip – with no basemap I had to plan using the GPS to approximate the centre of the target. I did this by just walking to the approximate centre and built the flight box around myself 🙂

The Native App

You typically need an app from the manufacture of the drone. In the case of DJI’s Maveric Pro they have an app called DJI Go. This app provides an SDK for your phone to integrate with the drone and a controller. It can be super fun to play with the manufacturer’s native controls. It is after all their hardware so they take responsibility for writing good firmware. This is also where cool features like follow me etc can be used. But after a while of playing with how cool this is you realise that it’s not really that helpful for planning a capture mission for a survey or GIS application. There are a lot of reasons for this but my reason is that I want to generate a point cloud and an ortho. These require processing and some pretty heavy math from hundreds of overlapping images.

The Capture App from Pix4D

I work for Pix4D these days. We can make an ortho, mesh and point cloud from the imagery and we provide an app for free to help capture good images. You can google around a bit, the support is super, but essentially you need the Capture App and the Firmware App which you can get by putting Pix4D into the app store or play store. Hardware is really not my specialty and I had some trouble understanding the need for both apps (don’t judge me) but it only took about 30 minutes to get everything working correctly, which is pretty OK.

Step 3: Flight Time

I’ll not describe all the details because this step is really really super fun to just explore for yourself. Basically choose mission type, set altitude, and press go with trepidation. Here are some take off photos. It’s always a concern when you’re not sure when the drone will come home but I’ve not lost one yet 🙂

Thanks for reading. There will be a follow up post on what to do with these images once you’ve got them! But here a sneak preview of a cool point cloud and textured mesh I’ve just completed.

Lucas

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