The other day I had a chance to return to my alma mater – The University of Colorado at Boulder. There, I got a chance to meet with the team running the newly renovated Fiske Planetarium – a state-of-the-art facility that can handle 8K image files. What this system can do may amaze you – and it opens up interesting possibilities for other domed environments.
The Fiske Planetarium’s primary mission is to serve the needs of the astronomy and astrophysics departments at the University by providing a visualization system for research and undergraduate astronomy courses. Secondarily, it provides education and training for students of all ages, including University students. While not a commercial facility, Fiske does offer programs for the public and local K-12 schools. They have a paid staff of six and about 25 student volunteers that help run the facility.
In December 2012, they began a renovation project that should have been a $4M 1.5 year project that was done using $2.5M and completed in a short 10 months. The facility went from using a 30-year old star ball and slide projectors to a state-of-the-art 20-meter dome facility – and perhaps the most advanced in the country right now. Here is what the system is composed of:
- Six JVC SH7 4K native projectors connected using 4xDVI connectors, fiber-optically coupled to the playback servers
- Skyscan ND filter wheel on each projector to dim the output when used in combination with the star ball projector (to add lines showing the constellations, for example)
- A 20 million star-ball projector powered by LEDs
- DigitalSky2 operating system from SkyScan
- 24 servers with Windows OS and K5000 Nvidia GPU cards to drive each 2K signal to the projectors
- A server for Audio
- A server to synchronize (via Nvidia Gsync LAN interconnections) and control playback
- 8 render PCs built in-house to create the 8K content for playback
- A content creation studio powered by graciously donated HP workstations with a small dome for visualization of proxies for quality control.
- A new perf screen installed by dome vendor Astro-Tec including new insulation behind it to better control the environment inside the planetarium.
First, what does an 8K planetarium mean? It means the video pipeline is capable of playing back content that is 8192×8192 in resolution at 60 fps.
I asked why they needed a dedicated server for each 2K component of this image and according to Studio Manager, Chris Maytag, the overall stability and reliability of the system is so demanding that trying to process a 4K image on one server and use a 4-head GPU card might cause some glitches in playback, which would be very unattractive. As a result, they basically over-specify the system to assure smooth performance.
It also turns out that the render engines are all CPU based, which surprised me a bit as I was thinking many were moving to GPU based rendering of large video files. According to Maytag, they needed to use CPU render engines because their 3D & animation renderer, V-Ray, only supports a CPU pipeline. New algorithms are being developed to take advantage of the massively parallel processing that GPUs can offers and some algorithms may work well on some scenes and not so well on others. “GPUs are not the panacea for rendering large video files – the success will be very algorithm dependent,” notes Maytag.
So an 8K planetarium does not project 8K pixels. In fact, it projects a lot more so there is a lot of scaling that has to go on too – a task of the render engines. In a level dome environment like the Fiske Planetarium (as opposed to an inclined dome environment), content is created to generally have the focus of attention in the forward 1/3 of the dome from the bottom to about 60 degrees up. As a result, the Fiske Planetarium devotes three of the 4K projectors to fill this space offering the highest pixel density here, with lower density over the rest of the dome. I never knew that, but it makes sense. The resultant on-screen pixels from the six 4K projectors is about 28 megapixels once you account for losses of content and overlapped blended regions. Fiske projector6 To create the content, teams works to assemble the assets and create an animation of the action. This is created as an 8kx8k master, then a circular section of this is actually used to drive the projectors. The screen is also interesting. It is a perforated screen with about 1mm sized holes to allow sound to penetrate from behind the dome. But surprisingly, most of the screen area is made up of open space – maybe only 25% is actually reflecting screen surface. I believe this is needed to avoid cross light contamination. In other words, light from a bright object on one part of the dome can create so much light that is reduces the contrast on other parts of the screen. This is a common problem in simulators too.
Now to the demos. I saw a number of them at various native resolutions and frame rates. As expected, content that was authored in 8K at 60 fps looked significantly better than 4K/60 or even 8K/30. The 4K content is upscaled, but the 30 fps content is not interpolated to create interframes. All of the 30 fps content showed motion blur on faster moving objects, but according to Maytag, that’s because they have a big 20 meter dome and that will not be as obvious on the more normal 10-15 meter domes out there.
Then, Maytag showed two pieces of very innovative content. One was developed by a company out of LA who used a DSLR camera to create time lapse videos of incredibly beautiful nature scenes. What they did different was actually take hundred and sometimes thousands of images of the scene looking in many directions and stitch them altogether into one seamless multi-megapixel image on a frame by frame basis. These were assembled into a time lapse video loop, but they also added other elements to make it look more like real video like moving clouds, moving water and flying birds – all added later in a compositing step. This was very effective.
The second innovative piece of content was created in-house by Maytag and team. Here, they took some UHD footage that the football team coach gave them with a desire to show this in the planetarium to high value football recruits. What Maytag did was create a version that mapped this to the front of the planetarium and warped it in such a way that is now looked like a giant flat IMAX screen. I have never seen a planetarium or domed theater used in this way, but it was a novel and effective alternative presentation format. Could such a format be used for generous alumni to give them a special presentation like a live football game or other special event to make them feel good about supporting (contributing to) the University?
So there you have it. A state-of-the-art planetarium or domed theater can be used for more than explaining the universe, so put on your creative hats come up with the next cool idea.