I have always been excited at the possibility of 4k video in a planetarium dome. And so I was captivated with the recent introduction of a 360° video camera rig with 8x4k resolution. (Which translates to 4k domemaster resolution.) It also meant that I could increase the fisheye FOV from 180° to 220° and see the immediate ground surrounding the camera. In my opinion this makes for a heightened immersion experience. So I have spent the last two months experimenting and learning directly about the intricacies of shooting 360° video.
The 360Heros H3pro10HD is a 3D printed object. Meaning its one solid piece of plastic that is precisely engineered to fit 10 GoPro cameras into the smallest possible space. Its printed using aircraft grade plastic, so its durable and has been through a strenuous bend test to prove its strength over time.
Currently the 360° video community is tiny and little documentation is available. So I was on my own to figure out the potential problems, shooting subtleties, and overall workflow. This can be a tedious and nerve-wracking process. After all, with 10 GoPro cameras shooting in unison, something is bound to go wrong at some point. So alas, plan within plans within plans, theorize contingencies, and take notes of your experience. And now for you brave souls remaining, below are my own findings, tips, and thoughts.
Camera & Memory
— H3Pro10HD Rig
— 360Heros Aluminium Mount
— GoPro HERO3+ Camera – Black Edition (x10)
— Lexar 32GB microSDHC 600x [LSDMI32GBSBNA600R] (x10)
— Manfrotto 496RC2 Ball Head with Quick Release
— Headless Tripod
— Manfrotto 200PL-38 RC2 Plate
Extra Batteries & Charging
— Wasabi Power Battery [2-Pack] and Charger (x10)
— PowerSquid D080B-008K (x2)
— 7-Port USB Charger (x2)
— Pelican 1550 Case with Foam
— Fotodiox GT-H3Lens-Cap GoTough (x10)
Stitching & Rendering
— Autopano Giga & Autopano Video Pro [known as AVP in this blog post]
— GeForce GTX 770 4GB
— 360Heros File Data Manager
Big Picture Workflow
- Setup the Rig
- Shooting Workflow
- Import & Check the Footage
- Stitch & Render
There are different mindsets and considerations depending of what action you are performing. So I’ve split up up this information into 4 main sections.
Setup the Rig
- Put camera’s into rig (matching camera # to rig #)
- Press wifi-button on each camera
- Check that each camera’s recording settings are correct: Example Display
Its a bit of a trick to get all the GoPro cameras installed without touching the lenses. But having the plastic rig locked onto a tripod helps. I chose to permanently install the aluminium mount so that 7 of the GoPros are looking at the horizon. Since I shoot for a dome, this can ease stitching pains later on since often the objects of interest are in these camera zones. This leaves 1 camera pointing straight up and 2 pointing down at the tripod. Interestingly, if a camera fails then I can trade it out for 9 or 10 and still not lose any essential zones. So there is some redundancy there. I could also remove 9 & 10 altogether and still capture 280° of footage.
Also, removing the cameras from the rig is difficult due to the tightness of the plastic camera clamps. But this isn’t a complaint, its actually a good sign that everything is snug and won’t wobble during shooting. So to remove the cameras you must use a small flathead screwdriver (included with 360Heros rig) to softly wedge the plastic tab up from its locked position.
Its important to number each of the cameras and the memory cards with a sharpie. If a camera begins to act strangely then I can easily trace it back to the source. It also allows me to understand exactly where a camera is within the rig, which can be helpful for when the automatic stitching doesn’t work. This is rare, but can happen if the video frame is of a pure blue sky with no overlapping content to match up.
The first time you setup the cameras, you will need to setup the default video recording settings for each camera by hand. From that point forward the cameras will remember those settings. It is absolutely vital that each camera has the exact same settings.
Camera Settings for Best Resolution
— Protune: On
— Resolution: 2704×1524
— Aspect Ratio: 16:9
— FPS: 30
— Low Light: Off
— White Balance: Cam RAW
- Power ON the cameras with the wifi remote
- Check each camera for corrupt symbol (rare)
- Press Record on wifi remote
- Quickly check each camera for red blinking recording lights
- Motion sync the cameras. Twist tripod stem quickly. VERY IMPORTANT!
Whats the need for motion sync? Well the wifi remote doesn’t trigger all the cameras at the same moment. So instead AVP must sync each of the video clips itself, otherwise your footage could be offset on the timeline and look terrible. There are two options: audio sync or motion sync; but motion sync is more precise. All you have to do is quickly spin the whole rig back and forth to provide the necessary data calibration for AVP to use later. The audio sync needs a sharp fast snap to sync to, like a dog training clicker.
A wonderful aspect of using GoPro cameras is that one wifi remote can trigger all 10 cameras. So they can be remotely powered ON/OFF and record start/stop. The remote indicates how many cameras are connected.
Because each of the camera lenses are not at the same nodal point, you’re undoubtedly going to see parallax errors when stitched. There are some techniques to address this in AVP, but it’ll take time and hand polishing. But to combat this upfront, its wise to constantly be thinking about parallax when planning a shot. My suggestion is to keep the camera rig at least 10 feet away from everything. That can be tricky and not always an option, but its the guideline I try my best to follow. Know that the larger the environment that you shoot, the easier your stitch job will be.
The most difficult aspect of shooting for a dome is keeping the camera movement buttery smooth. Any subtle bumps in the footage will be greatly amplified on the dome. I tested a wheelchair and the motion was smooth but not perfectly parallel when moving forward. I also tested a motorized wheelchair and that produced satisfying results when used at the slowest setting. But the real perfection is with the use of a tracked dolly. Yet then you run into the issue of seeing the track within the 360° shot. So I used the Singleman Indie-Dolly with 12 feet of track and that was just short enough to not show within 240°-ish of the footage. Its incredibly smooth and the smallest movement forward looks stunning in the dome.
Perhaps the most frustrating aspect are the GoPro cameras themselves. GoPro’s are not exactly known for their dependability. Some things to watch out for:
- Camera battery life leaves me wishing for more. 1h 30m of shooting time is pretty good, but I haven’t timed it when continually turning ON/OFF the whole rig. So I have a total of 30 batteries charged and ready. I definitely turn off the cameras when not recording, as they eat battery life when in stand-by mode. I’ve heard that changing the settings from the default 3 red blinking recording lights and instead seeing only one red blinking recording light can help to save some battery life too. Leaving on the wifi overnight (blue blinking lights) will drain a battery life in 24 hours.
- Be sure to use microSD cards that are recommended by GoPro. Some of the other brands don’t write as fast as they advertise and this can lead to the camera stopping recording randomly due to a full buffer. I’ve had good results with the Lexar 32GB microSDHC 600x and the footage files have a constant data stream of 45mbits/sec, with no skipped frames. But in the future I’d suggest the 64GB version. Recording with 2.7k settings will allow you to record 1h 30m of footage. So using a 64GB card would double that. Dumping footage takes about 1h 30m of diligent work, so if you’re in the middle of a big shoot, the last thing you want to do is be interrupted. I’ve had absolutely no problems with the microSD cards. But if you have an “SD error” on the GoPro, accidentally deleted footage, or the microSD card is unreadable, then check out Test Disk.
- Occasionally a video file will corrupt. You’ll know because the camera display will show the corrupt symbol and you must push a button to continue. So this is something that I’ve added into the shooting workflow. Its not entirely clear what causes this, other than the fact that these high resolutions have a high data rate and sometimes the header doesn’t get written to file. Luckily the video data can be repaired when transferred to a computer. I’ve yet to have a case where the video data is lost.
- The cameras are not up to par when it comes to long duration shots. A continuous shot of 30 minutes would make me nervous. I had one occasion where a camera froze; meaning the firmware froze up and the battery had to be removed to reset it. And you’ll know its frozen, as no buttons will function. Either it won’t power on, won’t begin recording, or stops recording mid-shot. So as a precaution, I am always checking for the red blinking recording lights at the beginning and ending of a shot. Upon freezing, the red recording lights stop blinking and then it is no longer recording video. But any footage prior to the freeze is retained (though it might be corrupted).
- If the footage count on the front camera display isn’t identical between all of the camera’s, then that camera wasn’t recording during the shot and so that channel will be missing for stitching. Either one camera didn’t trigger via the wifi remote or the camera firmware has froze. So again, always check for the red blinking recording lights at the beginning and ending of a shot. Its obviously wise to keep notes in your shot log of these mishaps.
- Even with all that said, they perform pretty well. For example, out of 57 total shots: 4 shots had corrupted files which were all later repaired in full. 1 essential camera had a battery die and lost half the shot. Twice a camera wouldn’t sync with the remote, but it was a non-essential camera facing the tripod and recorded fine without it (it needed a battery reset). And once an essential camera froze up after I had started recording and the shot is unusable. So obviously, get multiple takes of each shot!
Shooting for a dome means that I don’t actually need the complete 360° of footage. So I use a tripod to increase stabilization. Some people use a monopod that has tiny tripod legs. That is useful to capture as much FOV as possible and actually opens up the possibility of complete 360° with some trickery in post-production to hide the monopod itself. But in moving shots, a tripod is required.
Keep a shot log while shooting on location! It will be invaluable since you will undoubtedly forget the shot locations, problems, noted bumps/wobbles, bad takes, reminders, and such. Be diligent about this, as having a shot log will make your importing process much smoother.
Each of the cameras are locked to auto-expose. And I mean permanently locked off from user control. It’s just the way GoPros have always been. But luckily AVP is extremely powerful in its exposure/color correction. Yet it can be difficult to deal with when you’re very close to a bright light source and only one camera has a wildly different exposure value. Even still, AVP can correct between pretty serious exposure differences since the GoPro cameras have excellent latitude.
An exciting option is to shoot in slow motion at 240 FPS. Using this FPS will reduce your end output to 1k fisheye (2x1k equirectangular). Or shoot at 120 FPS and output to 2k fisheye (4x2k equirectangular).
The bottom of the 360Heros aluminum mount has an 3/8″ screw hole. (Contrary to the typical 1/4″.) So you will need to get a special quick release plate to put it on any tripod.
Battery Runtime Test
— Official battery, using wifi remote, recorded 2.7k footage for 1h 32m
— Wasabi battery, using wifi remote, recorded 2.7k footage for 1h 19m
Import & Check the Footage
Wherever you shoot, you’re going to need a laptop and external hard drive to dump the video data. For each hour of video taken, you will need about 340GB of free space.
Using an external USB 3 microSD memory card reader is an absolute requirement. Since each card can hold 32GB, you’ll want to be able to dump the data quickly. So dumping the files straight from the GoPro cameras isn’t an option since the USB 2 speeds are too slow. Even with USB 3 speeds, it still takes about 1h 30m to dump all the micoSD cards to disk.
Since each camera creates footage with similar filenames, its imperative that the you rename the videos files as they are copied to your computer. Otherwise the possibility of overwriting data is quite possible. But renaming by hand isn’t needed if you use the 360Heros File Data Manager to easily dump the video files for you. I underestimated the usefulness of this command line tool. It automates the process of appending the camera number and project name to the video filename, and then it dumps the footage into a folder. Here are the quick instructions of its use. Don’t worry, although it doesn’t have a GUI, all you need to know is how to CD via the command line prompt.
Finally its time to see how the footage actually turned out. Hopefully you have kept a shot log to help inform this process. But I always create a spreadsheet and keep track of the following per shot:
- Concatenate needed? Due to the FAT32 memory card format, any shot that reaches 3.8GB will be automatically split into separate video files. (Or with 2.7k settings: every 11m 38s)
- Corrupted video file? Infrequently a video file will corrupt; meaning the header won’t write to file. Luckily the video footage can be repaired.
- Missing channels? Rarely a GoPro camera will freeze up. Either it won’t start recording or freeze up during a shot. Hence the need to check for the blinking record light in the beginning and ending of a shot.
- Shot length match between cameras? If a camera battery dies in the middle of a shot, then you’ll still get the footage up to a certain point for that camera. But obviously the rest of the cameras will continue recording.
- Shots organized? Each collection of 10 related video files will need to be placed into its own file folder to best keep individual shots organized for stitching. So from the huge list of dumped files you must figure out which cameras are related to one particular shot. This is definitely tedious and especially confusing with files that need to be concatenated. My shortcut is to organize the files by Date Modified and have the Length attribute visible.
Stitch & Render
Finally you have all your shots organized and ready to stitch in AVP. What’s amazing is that you don’t need a AVP template for the specific camera rig layout. Just drop all the videos into into AVP, synchronize, and stitch. It uses the overlapping content between each video to automatically create a 360° projection. Its not always perfect, but its damn good most of the time.
Here are a few sources that were helpful in learning Autopano Video.
— Autopano Video Wiki Documentation
— Autopano Video 101
— Autopano Video Forums
— 360Heros FAQ
Final Render Resolution
AVP can render whatever type of projection you need to a frame sequence. Full resolution examples below. (These are not polished renders, just the initial automatic AVP stitch.)
— Equirectangular (Spherical): 8192x4096px
— Fisheye (FOV 180°): 4096x4096px
— Fisheye (FOV 220°): 5000x5000px
I was happily surprised with the fact that upon increasing the FOV to 220°, then the final render resolution increases to 5k. This is possible because more footage is viewable at a higher FOV, and so you are effectively “squishing” more pixels into the fisheye image. So when I project it onto the dome at 4k, then I have the added benefit of increased sharpness since the video has been downscaled.
I render using the Equirectangular (Spherical) projection because often I want to add slow movement to the virtual camera in After Effects with the Navegar Fulldome Plugin.
The only difference between Autopano Video and Autopano Video Pro is the GPU render option. Which makes a huge difference in render times. When rendering at these high resolutions, you need a graphics card that has lots of memory. So the GeForce GTX 770 4GB has a decent amount of cores, lots of RAM, and at a good price point.
Final Render Statistics at Full Resolution (Equirectangular)
— CPU: 0.05 render fps – takes 12 hours to render 1m 30s of video.
— GPU: 1.5 render fps – takes 1 hour to render 1m 30s of video. (GeForce GTX 770)
Right when you get the footage, you’ll just want to see a 1k preview quickly. The good news is that fisheye rendering at 1k in AVP is quite fast at 10fps on the GPU.
As of AVP 1.6, they have implemented a stabilization algorithm to help smooth out bumps. It definitely reduces any bumps by 50% and I read that will be improved in the next few versions. They are also adding a timeline which can keyframe cameras and color; which means that you can interpolate between stitches. That is powerful when trying to fix parallax on a moving dolly shot. Its also very helpful when trying to fix an unruly camera whose exposure is way off from the others (such as a camera pointing at the ceiling).
When using GoPro cameras, the stitching can be optimized since the camera sensors aren’t perfectly aligned/centered with the lens and therefore each have their own lens distortion model. So you can pass AVP this information in the the Lens Distortion Correction settings. As of version 1.6 the settings have been moved and updated.
The video and render examples showcased in this blog post do not yet have their stitches hand polished in AVP. They only use the initial automatic stitch because I just wanted to see the results quickly. So any obvious seams and parallax errors you see could be fixed with some hand polishing. I’m still learning how to best use the software. But you need to run alot of experiments to get polished results and possibly even composite multiple AVP renders in After Effects to get the most seamless results.
The GoPro cameras do a great job of capturing color and have excellent exposure latitude. But a photo filter in After Effects is often needed to color correct for tungsten lights or daylight. Then the colors need a big saturation boost to look optimal in the dome. And the use of curves can enhance dark colors instead of using contrast. And maybe a slight touch of sharpening.
This AVP explanation could easily be a whole write-up of its own. Perhaps in the future I’ll share my experience once I’ve learned more. I’m currently in the process of stitching 57 shots (900GB total unprocessed) taken at the NASA Goddard Space Flight Center. It was an intense 3 day shoot and we got some amazing 360° shots that I can’t wait for you to see in our upcoming planetarium show production.
Lastly, if you’re shooting with the stereoscopic 360heros rig, then you will have a slightly different workflow in AVP. I don’t even want to fathom the bizarre difficulties with 3D 360 video.
Both the normal and stereoscopic 360 videos can easily be experienced on the Oculus Rift (using Kolor Eyes, which is free).
And that’s the Gist of it
As you can see its not the faint of heart, as it demands a pretty wide range of technical knowledge. But the results can be simply stunning. This is a newborn medium and there is alot of room to grow. But its an exciting time for fulldome show producers, hyperdome possibilities, and the Oculus Rift community. 4k video in the dome has long been a dream and I think this is an bold step into a fascinating frontier.
Update: November 21, 2014 – Looking for a simple description of 360 video and how it works? David Rabkin and I wrote a paper that was presented at the 2014 GLPA conference: video of the presentation & PDF paper. So if you want the basics without getting too technical, then this is your best bet. Full cost assessments: H3Pro10HD or H3pro7.
Update: November 20, 2014 – Here is an interesting roundup of 4k video cameras in the marketplace. So it seems that 360 video is still the best option for creating 4k domemasters, especially since 4k video cameras still don’t have sensors with at least a 4k vertical. So we are still a number of years away from 8k video cameras being mainstream. Yet its quite interesting to see 4k become a standard within video camera equipment.
Update: October 30, 2014 – If you are wondering about the new GoPro Hero4 camera… Having each camera shoot at 4k 30fps is amazing, but it comes at a cost. Results from the 360 video community suggest that you can only shoot for 30 minutes before needing to cool down the cameras. And sometimes the Hero4 camera will forcefully shut down due to overheating.
Update: March 12, 2014 – The GoPro cameras have a firmware update available that allows you to shift the automatic exposure through the iPhone app. I’m curious to experiment, though I’m cautious of the added workflow of getting the optimal exposure and updating ALL cameras settings for each shot. Also, while its too crazy for me (since it voids your warranty), there are ways to hack a GoPro camera to truly lock down the exposure.