Field Test

On the weekend of May 18th I set about conducting my first test on the trolley building.  That Saturday I, with the assistance of my brother, photographed what we could of the building from the ground.  The following day at around 7:30 am we began capturing photos with the multi-rotor.

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Much of this process is still new to me and the proper methodology for taking the photos from both the ground and the air so they might work optimally in Photoscan is still very much a work in progress.

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There are many things to consider.  Such as the best distance from the target object and the best angle for the camera to take the photos from.

A compact digital camera is used to take the photos from the multi-rotor.  Rather than using a servo to actuate the shutter button I opted for a software solution.  The problem with using the servo actuator arm is that for every image that needed to be taken the operator of the multi-rotor would have to flip a switch on the transmitter.  Having to take the photos in this way makes for added distraction while piloting the multi-rotor.  As I am using a Canon Powershot Camera I was able to find a better solution.  There is a custom firmware, CHDK which is available here.  It allows one to non permanently replace the factory firmware with a much more powerful version.  Along with many other features it allows one to shoot in RAW and to run custom scripts.  I have used the custom script feature to make the camera automatically take images in about 2 second increments.  So when this is employed on the multi-rotor one of the things that is very important to get right is the pacing at which the multi-rotor is moved.  As it is very important to have as much overlap as possible in the photos.

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All in all, the day was pretty successful.  But as the morning progressed, winds began to gust between 15 to 30 mph.  These conditions are not ideal for the multi-rotor and may cause erratic flight behavior.  I decided to cut the day short so that I might prevent a crash.  But not before I tried out the on board video broadcast system with my video goggles i.e. first person view flight.

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The image above is a light weight video ground station which receives the video signal from the multi-rotor and rebroadcasts it to my video goggles.  This system has been used before with other aircraft successively at ranges of up to 2 km.  Unfortunately this was not the case for this test.  For some reason after climbing to about 10 meters, the video signal cut out completely which resulted in a bit of a hard landing.

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Luckily only one arm was damaged and it can be easily replaced.

Next is processing the images we took.  The next post will cover this.

Images in this post courtesy of Mariano Ulibarri.  Many thanks to he and Tyler Grassie for all of their help.

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