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Dome / Wisdome

The dome theatre is the largest space at the centre: a tilted fulldome theatre used for public shows, stereo research presentations, lectures and events. It is also the most interconnected space — a fault here usually involves several layers at once, so read the troubleshooting method before working in it.

Inside the Wisdome fulldome theatre

At a glance​

SurfaceSpitz NanoSeam dome, 14.8 m diameter, tilted 27°, ~165° of sphere
Projectors6 × Barco XDL-4K30 (4096 × 2160 per eye, 30 000 lumens each) plus 1 × Barco F90-4K13-3D insert projector
Total resolutionroughly 8192 × 8192 pixels across the curved surface
Stereo6P RGB laser — two sets of RGB wavelengths, one per eye, separated by passive glasses. 120 Hz total refresh rate
Render clustersATLAS and DRACO (NVIDIA RTX 6000 Ada Generation in every node), BRAVO (NVIDIA Quadro RTX 8000 in every node), plus SUSHI/HASHI/FISHY
Signal distributionBarco ENA-340 encoders/decoders over a 10 G network (52 units facility-wide)
Audio7.2 system, run as 7.1; DiGiCo mixer, Crown amplifiers; 4-language tour guide system
LightingETC Element 40 desk, 142 × Philips Color Kinetics fixtures, 4 zoomed spotlights
ControlDome Control panel on the iPad and in the control booth; Showmaster 1 (showmaster1.c.itn.liu.se), Medialon

Dome facts​

Useful when a visitor asks, and when judging what the room can actually do.

The dome itself​

  • 14.8 m in diameter, suspended partly from chains in the ceiling.
  • Built from a large number of perforated aluminium panels on a frame. 23 % of the surface is holes, which lets both ventilation and the sound from the 7.1 system through.

Glasses​

  • The 3D glasses are passive — they pass a different image to each eye by filtering wavelengths.
  • The previous active glasses ran on batteries and alternated which eye was blanked several times per second. The passive ones need no batteries, cannot die mid-screening, and can be washed in a dishwasher instead of by hand.

The passive 3D glasses used in the dome

Projectors​

  • Six 6P RGB laser projectors, each at Cinema 4K (4096 × 2160). The curved surface has a total resolution of roughly 8192 × 8192 pixels.
  • Two projectors cover the cap and four cover the walls, with physical barriers and some overlap keeping brightness even across the surface. The previous generation was also six projectors, but at roughly 3936 × 3360 pixels in total.
  • Each projector produces up to 30 000 lumens, up from 7 000 lumens for the predecessors.
  • 6P RGB laser means six primaries: red, green and blue, each split in two at a wavelength break point. Differently filtered glasses let both images be shown at the same time while each eye sees only one — which is where the 3D effect comes from, without active glasses. The total 120 Hz refresh rate also gives very smooth playback.
  • Each projector weighs about 250 kg, excluding its liquid cooling. At full power a projector draws about 3.5 kW and its chiller a further 2.0 kW.

More background is available in SweClockers' articles about Visualiseringscenter C from 2020 (the current installation) and from 2010 (the opening year).

How video reaches the dome​

Encoder side — from render node to switch:

Decoder side — from switch to projector:

Because the dome runs passive 3D stereo, every computer-to-projector link is dual-headed: there are two parallel chains between each render node and each projector — one for the left eye and one for the right eye. Each chain is a DisplayPort cable from the GPU to an ENA-340 encoder, then two 10 G fibre links across the switch (a 4K signal needs ~18 Gbit/s — more than one link can carry), then an ENA-340 decoder feeding a second DisplayPort cable into the matching eye input on the projector — so each projector is fed by two decoders.

Each layer in that chain is a place the image can stop, and because every layer exists twice per channel (left and right), a fault in one chain affects only that eye while a fault shared by both chains — the render node, the switch or power — takes out the whole channel. The Barco status page tells you in seconds whether the encoder/decoder half of it is healthy.

Projector and chiller positions​

The six XDL projectors are spread around the building and each has a separate chiller, often in a different room from the projector it serves. This matters during troubleshooting: a projector fault may actually be a chiller fault one floor away.

ProjectorProjector placementChiller placementCovers
1Table near the RWC, north-west cornerAbove the RWC, on the pre-show roof (north-west)Ahead and left, along the rim
2North-east cornerPre-show roof, north-eastAhead and right, along the rim
3Floor, south-east cornerTech corridor downstairs, first shelf on enteringBack and right, along the rim
4Floor near the elevator, south-westDownstairs, second closest to elevator room doorBack and left, along the rim
5Floor, north-east cornerPre-show roof, north-eastTowards the cap, forward and right
6Floor near the elevator, south-westDownstairs, closest to elevator room doorTowards the cap, back and left
7 (insert)Above the control booth — elevator or ladders—Straight ahead

Addresses and web interfaces: Projectors.

Content formats​

Fulldome content is fisheye (dome master) rather than flat video. Getting the format wrong is one of the most common "the show looks wrong" causes, and it is a content problem, not a projector problem.

TODO verify with senior technician

Document the accepted dome master resolutions, frame rates, codecs and colour space for each playback path (C-Play, OpenSpace), and where incoming content should be placed for ingest.

Reference pages​

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