From Multirotor Pilot Issue: 8
by Peter Hejl
It’s only been a few years since multirotor aircraft became available to the market and one can only marvel at how far along this industry and hobby have gotten over such a short amount of time. Looking back at the days when a 600 TVL camera was a pretty good crowd pleaser and a gimbal was something that most of us could just dream about, that time now seems like the “flip-phone era” of multirotor aerial videography. It is quite exciting to watch individuals and companies take this technology, add a cool idea, a little creativity and quite a few trials and errors to transform all that into something new, awesome and useful to others. We can all thank these creative and innovative minds for moving the industry forward and providing us with useful tools and toys we all get to enjoy.
360Heros is an Olean, New York-based company, whose invention, the 360Heros GoPro mount, a flexible aircraft grade nylon holder, has made it possible to combine up to 14 GoPro cameras and use them to record 360-degree fully immersive video or stills. Each camera is mounted at a specific angle so its field of view overlaps portions of the surrounding cameras’ field of view. That overlap eliminates any gaps in the footage and allows for flexibility at the seams. When all the GoPros are recording, they capture video at the same time and cover the entire 360 by 180-degree area. After processing, the 360-degree immersive videos can then be viewed on Virtual Reality headsets (Oculus Rift or Samsung Gear), an iPhone/iPad and Android devices (using Kolor Eyes 360-degree video player app) or even on YouTube (when using Google Chrome browser). These fully immersive videos or still pictures allow the viewer to experience what they’re watching in an entirely different way, fully surrounded by the environment and action, able to look around and explore. The idea of becoming your own “director”, given the ability to customize your viewing experience by choosing where to look, is a pretty powerful one.
VR HEADSET REVOLUTION… AGAIN?
Virtual Reality headsets have made a few attempts to become mainstream in the past, but for a few different reasons (price, technology) have for the most part failed to do so. The advances in technology (smartphones, cameras) have made the necessary components small enough and relatively reasonably priced, so more and more people will be enjoying their games, videos and tours through their own Virtual Reality headsets or headset gear that turns their smartphones into powerful immersive image devices. While the technology is still being finetuned and evolved, this time around the VR headsets may just be in a position to finally become mainstream in gaming and video markets. As an example, the Samsung Gear headset that turns their Galaxy4 smartphone into a 360Degree VR machine can be had for $165.
The 360Hero camera mounts can be used in just about any situation and environment imaginable, including under-water (with 360scuba). For the ones that feel that the 360-degree viewing experience may just not be mind-blowing enough, a 3D version is offered – yes, 360-degree HD video in 3D, which must surely be just one spot beneath the possibility for time-travel on many techies’ bucket lists!
WILL IT FLY?
By now, any multirotor videography enthusiast reading this is surely thinking of the potential to combine this cool gadget with our flying platforms and use them to create awesome fully-immersive aerials. When a client approached me about the possibility of doing just that, I was easily sold on an opportunity to work on their fully immersive university campus video tour project. The project, among other things, involved flying 6 GoPro cameras in a 360Heros mount suspended four feet from the bottom of our DJI S-900.
Admittedly, I may have slightly underestimated all the challenges of executing this project and there were quite a few to overcome. There were many trials and errors and days spent designing a solution that would give us good quality results. The next few paragraphs look at the challenges and explain our approaches to them. They should serve more as idea drivers, as I’m sure there are and will be many different approaches to this as the technology evolves.
KEEPING THE MULTIROTOR OUT OF THE IMAGE
The biggest challenge of them all has been designing a system to att ach the 360Heros to the copter, while keeping the copter as much out of the picture as possible. We used ten and six GoPro fully immersive (360 by 180 degree) mounts, which meant we had to find a way to hang the mount as low under the copter as possible.
For the ones not willing to sett le for a small copter image overhead in their 360 experience, 360Heros off ers a helmet/UAV mount which does not “look up” while still offering a 360 by 120- degree experience. Alternatively, a GoPro can be placed on the top of the copter to capture the sky, which can be later stitched in. We had some mixed results with this approach, as it really depends on the correct positioning and what the cameras capture. Flying under or next to tall objects may cut part of the object off and replace it with a shot of the sky, which may not always be desirable.
Another approach is replacing the copter in the image or video with a “floating logo”.
Perhaps the best idea to overcome this came from the cooperation between 360Heros and Oregon-based Aerial Technology International (ATI). Their creation is called 360Heros Aerial ORB (in pictures), which is a hexacopter that doubles as a 360Heros mount. There is a GoPro in a special “orb mount” attached to each of the arms, and an additional three GoPros in the mounts facing up and down, for a total of 12 cameras. The Orb is currently a development project and an important step toward great 360-degree UAV videos. It is one to keep an eye on as 360Heros with ATI keep evolving this great idea.
We resolved to find a way to hang the mount as low under the copter as we felt comfortable with and leaving the copter in the image.
The six GoPro mount with the cameras (Hero4 Silver) weighs 725 grams (10 GoPro Heros at 1150 grams), and our rod and copter attachment added another 500 grams. We had to figure out how to safely and reliably hang the mount under the copter while in mid-air.
The mount had to be able to give-in a litt le in order to be allowed to sway during hard stops and the occasional wind gust, but not too much so it doesn’t become a pendulum and take the copter down. If the mount is allowed to sway too much, the copter is naturally trying to get back to level, swinging the “pendulum” in the other direction, eff ectively making it swing even more. This motion renders the video useless and may eventually over-power the copter and bring it down. This has almost happened to us during a few of our tests and it was prett y nerve-racking to watch. We managed to catch it back, but once I had to lean the dummy weight we used into a snow bank to stop it from swaying.
After trying a few different ways to mount this rig onto the copter, I came up with a solution to create a “cone” out of a stainless steel olive oil dispenser (the one you usually see on a restaurant table) by cutting the bottom of it off and cutting out a slot along its entire width, wide enough for a 3/8 threaded rod to pass through. Then I used this cone as a form to create another cone on the end of the 3/8 threaded rod out of Polymorph. Polymorph is a moldable plastic that comes is the form of pellets that dissolve into a substance similar to Playdough when immersed into hot water and can be molded before hardening back to plastic. As an alternative, this can be 3D printed.
Now I had two cones: an outer one (receiving) for the copter and the inner one for the 360 Heros mounting rod. I attached the receiving cone to the S-900 landing gear and rail system and then used an epoxy to attach a carbon fiber rod to the threaded rod on the inner cone, finally adding another threaded rod to attach the 360Hero mount to the other end of it.
The idea was for me to lift off and then have one brave soul hang the rod with the camera mount to the copter in mid-air by reaching up and engaging the cone at the end of the rod into the cone attached to the copter. Since the outer cone was stainless and cut along the side, it provided just the right amount of “give”, which allowed for the 360Heros to sway a little, but stop again in the center.
Alternatively, a swivel joint wrapped in some tape or shrink wrap can be used to allow for the mounting rod to sway a little.
CENTER OF GRAVITY AND GAINS
Once we got the copter with the mount safely in the air, I began to fi netune the center of gravity and the gains. Hanging something this low while in flight makes it a bit difficult to determine where the center of gravity is. By providing the A2 flight controller with the distance from COG measurements, we are essentially telling it what point in space to pivot around when responding to the pilot’s commands (pitch/roll) or when trying to get back to level. I chose to fi nd the right point that would give me minimal sway on the rod, instead of trying to figure out where the actual COG was. I started with a good estimate and watched the copter to determine the “pivot point”. I then tried a few different locations along the rod, until I found an ideal one, just about where the rod exited the cone.
Gains also needed to be adjusted. While I chose to land and launch again for every COG adjustment, we used the DJI Assistant app to fi netune the gains in mid-air. I tried sett ing the gains low at fi rst, with the idea of providing some smoother motion and help keep the “pendulum eff ect” controlled, but it actually had the opposite eff ect and made the copter more diffi cult to control. I found the ideal gains to be as high as possible without causing quick oscillations, so the copter is really locked-in. A good piece of advice is to keep checking the motor temperatures every time the gains are increased, as the motors tend to heat up a bit more.
VIBRATIONS AND “SHAKES”
The biggest deal was keeping the cameras as steady as possible, while moving really slowly throughout the scene to introduce a feel of action. Fast motion may cause nausea in some of the viewers, so I would strongly recommend sitt ing down even when viewing slower moving clips. There are no gimbals for these cameras (yet); so multiple takes are oft en necessary to get a useful shot. Wind is an enemy here and it’s important to choose a day with minimal or no wind to keep the machine as steady as possible. The vibration introduced by the multi-rotor can also cause visible jello eff ect or shaking in the video. To help with this, we made sure that the props were balanced (using a Drone Vibes testing app on an iPhone att ached to the arm) and hung the receiving cone on the clean plate (rails) of the S-900 frame, which is insulated from vibration by 12 compressed rubber dampeners.
MANAGING THE CAMERAS AND PROCESSING THE FOOTAGE
Having to manage this many GoPros and footage is not an easy task. 360Heros off ers a USB hub to help connect and charge up to 7 GoPro cameras. A GoPro remote can be used to trigger the 360Heros at the same time, however since it requires running the cameras’ Wi-Fi, it is not advisable to use this feature on multirotors with 2.4GHz RC controllers. The close proximity of multiple Wi-Fi devices is guaranteed to cause interference and may lead to a fl y-away or crash.
Media management is important; keeping the fi les organized and in order makes the stitching much easier later. While the GoPro clips are fairly small, the amount of storage space needed and the performance of the computer used to process and stitch the footage are also important things to consider.
There are a couple of soft ware options available to process and stitch together the footage, Kolor and Video Stitch, both with their pros and cons are worth researching.
While 360-degree immersive video technology is still prett y much in its infancy, it is a great tool with amazing potential to become mainstream within next few years. Flying the 360Heros was a great experience and while there are more challenges left to overcome, this was certainly a fun and challenging project to be a part of. I can’t wait to see where this technology heads into the future and hope that our endeavors will contribute to evolving the use of multirotors to capture amazing, fully-immersive videos.