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.



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.



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.


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.



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.



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.

Initial Testing

Once I had the new gear installed I was able to install and configure the camera gimbal.



With all systems tested and functioning correctly the multi-rotor was ready for field tests.  I decided to use the old trolley building on the campus of New Mexico Highlands University as my first subject.  This building is significant in that it housed horse drawn trolleys which were used in Las Vegas around the turn of the 20th century and the second being that the shell of this building will serve as the foundation for the future home of the Media Arts department.

This allows for an opportunity to record with photogrammetry the renewal of this building into a modern instructional facility.  I hope to model the building in its current state and after its renovation.

Parts of this structure are over two stories tall which makes for a perfect opportunity to test my multi-rotor as it has been designed for just such a subject.  It will also be a good test for determining how small of an area the multi-rotor will be capable of functioning in.  There are power lines, trees, and guide wires relatively close to the structure.

I will post videos, photos, and hopefully preliminary models of the tests soon.

Proof of Concept

Not long after returning from Cuba I began testing my concept.  I had only recently started experimenting with quad copters and had a working one which I had built several months before.  On it I had installed a mount for a Gopro camera.  The Gopro is capable of taking series of timed images and has a 7 mega pixel sensor and as such should be perfect for capturing images for this project.

Before I conducted my first test I did some reading online about using Gopro cameras for this type of application.  There were limited sources and from what I could find people had used them with some success or stated out right that it would not work.  The latter reasoning that the extreme fish eye, variable exposure, and CMOS sensor would render it useless for this application.

Despite this I pushed forward with my tests.  My first subject being my house.


The experience taught me many things.  Most importantly that my concept could work and could work in tight spaces.  I also found that using Agisoft Lens I was able to successfully create a lens calibration XML for the Gopro which meant that the collected images could be processed using Agisoft Photoscan.  I processed the images on the lowest settings and the results were encouraging enough to move forward.



It is important to note that this was processed on the lowest settings with very few photos.

So with some lessons learned I pressed onward.  I realized that the multi-rotor I used for this test was not ideal for several different reasons.

  • It is heavy and because of this it had a flight time limited to about 7 minutes of safe flying.
  • The motors and the speed controllers which they attached to are not ideal.  The former being not well balanced and the latter being not as responsive as I would like. The importance of balance and responsiveness will be explained later.
  • It was unstable and a lot of this can be attributed to my relative inexperience with the controller I was using but also to the vibrations which existed in this multi-rotor as tested.
  • The use of the Gopro, though successful, might not prove ideal and the camera mount on the multi-rotor would not accommodate cameras of any different size.
  • Finally during later testing this multi-rotor crashed and was basically destroyed.

These early tests and the information and experience I gathered from them shaped the idea of where I wanted to go from there and what I wanted to accomplish.  I would build a new multi-rotor and it would be designed to be higher quality, lighter, and more effective while keeping price to a minimum.  It should feature:

  • A lighter and more resilient frame.
  • Higher quality components.
  • A servo stabilized 2 axis camera gimbal.
  • The ability to carry a larger variety of cameras i.e. Gopro or compact digital.
  • The ability to remotely trigger the camera shutter.
  • Flight times of over 10 minutes on one battery.
  • Tuned and effective controller for the multi-rotor.
  • The ability to broadcast live video from the multi-rotor to either a ground station or video goggles for first person flight.

With this in mind I started researching parts and kits.  The results of which I will be posting as the project continues.