by Alan Thompson (NOSAS)
I’ve had my Quadcopter for over a year now, had great fun flying it, and have produced many interesting images. I recently showed a selection of images at a NOSAS evening, and was asked if I would write this blog and share some of the things I’ve learned along the way.
Of course the pictures are what it’s all about and even if you’re not interested in my comments, I hope you enjoy looking at them.
Inspired by some of the wonderful aerial photos (APs) I’ve seen (for example on Canmore) I have long thought how good it would be to be able to take such pictures of our own archaeological sites.
For several years I have been interested in photogrammetry and experimented with that, especially of rock art where the production of a 3D surface and use of computer generated lighting and shadows can give some great effects.
In 2013 I began to investigate kite aerial photography (KAP) but the possibility of using a Quadcopter also emerged and I realised that technology and prices were moving so quickly that it might be a better option. In early 2014 I decided that the only way to learn was to buy one.
The Quadcopter – getting ready to fly
Most amateur Quadcopters are sold with very wide angle cameras, with the intention of video recording, and also providing a pilot’s view (called first person view or FPV). This is less than satisfactory for archaeological aerial photography, and so I bought a Quadcopter without a camera, with a view to fitting my own.
The camera is obviously critical, and it needed to be light (ideally <300g including battery), robust, of good enough quality, and with an interval timer. Unfortunately I could find no such camera. All those with interval timers are heavier, for example those used for kite aerial photography. A solution can however be found in that a group of people spend their time hacking the software of Canon cameras (google CHDK) and provide a hacked version for some models which enables an interval timer to be run.
Having bought and hacked my camera and got the interval timer working I had to fit it to the Quadcopter. The main problem is the high frequency vibration from the rotors which renders the pictures useless. A suitable anti-vibration mounting was needed, all within the weight limit.
Next, to prepare for the first test flight. The web (YouTube) is full of videos of alarming crashes and fly-aways. The Quadcopter instructions are daunting saying that a first flight should be from the middle of a large field, with no wind and no people about. There is also the matter of insurance (it could certainly hurt someone badly), and the possible need for a CAA licence. The regulations here are changing quickly but at present as a hobby flier I can insure through the British Model Flying Association (BMFA), and (unlike a professional archaeologist) have no need of a CAA licence provided I fly within line of sight, avoid certain areas (eg near airports) and limit the height. I would again emphasise that this is all very much in the news and changing and my observations here will quickly be out of date.
The first flight is bit nerve-racking, but set to auto mode the Quadcopter uses its own GPS and compass and is set so that (more or less) if you let go of the controls it just hovers where it is. Flying in this mode is reasonably straightforward. I have not dared try any of the advanced modes as yet.
Continue reading →