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Image quality: stereo, blending and sync

Part of Dome troubleshooting — start there for quick triage. These are the symptoms where an image is on the dome but looks wrong: doubled, misaligned or tearing.

TODO verify with senior technician

The causes and step sequences on this page are informed reconstructions pending review — see the note on the main troubleshooting page.

Stereo (3D) ghosting or crosstalk​

Likely causes: playback is in the wrong stereo mode; content is not actually stereo; wrong glasses; eye channels swapped.

  1. Check the playback mode first. Mono content in a stereo show mode, or a left/right swap, produces exactly this symptom.
  2. Confirm the audience has Dolby 3D glasses — glasses from another venue or another 3D system will not separate the 6P laser wavelengths correctly.
  3. Verify the per-eye assignment on the render nodes. On the ATLAS cluster the stereo is emulated through dual DisplayPort outputs (i.e. passive stereo) — see ATLAS cluster, including the NVIDIA settings screenshots.
  4. Only if all of the above are correct should the projectors be suspected. That is an escalation, not a runtime fix.
Image to add

Photo or screenshot of the dome surface showing ghosting/doubling in a 3D show, so the symptom can be recognised quickly. Suggested file: static/img/dome/troubleshooting/stereo-ghosting-example.jpg.

Visible seams or misaligned blending​

Likely causes: a projector was physically knocked or serviced; a node is rendering the wrong frustum; calibration was not restored after a GPU driver change.

  1. Establish whether it is one seam (one projector moved or is rendering wrong) or all seams (a global calibration or content-format problem).
  2. Check that the affected node is rendering its correct channel — a node restored from a backup or renamed will happily render the wrong part of the dome.
  3. Check whether a GPU driver or display-configuration change happened recently. Warp and blend do not survive a display topology change.
Do not re-warp

Adjusting warp or blend is not a troubleshooting step. It is a calibration task with its own procedure and it can make the dome unusable if done wrong. Escalate.

Image to add

Photo of a visible blend seam on the dome surface (one-seam case), for recognition. Suggested file: static/img/dome/troubleshooting/seam-example.jpg.

Cluster nodes are out of sync​

Symptoms: tearing across a blend seam, one channel a frame behind, stutter that moves between channels.

  1. Check the Barco status page: an encoder whose resolution ends in p60 is not synced properly — correctly genlocked signals end in p59. A decoder marked yellow means its signal has no genlock, which is usually a resolution mismatch between the encoder and the decoder. See Reading the colours on the Barco status page.
  2. Confirm which cluster is in use and which node is the sync master. For ATLAS the sync master is ATLAS-01.
  3. Check the NVIDIA sync configuration on the master and on a sync node — reference screenshots are on ATLAS cluster.
  4. Restarting is safe in any order: every node runs a sync fix script at startup, so there is no "sync master last" requirement anymore. After rebooting, wait until the command line popup and the blinking on all machines have finished — when they stop, everything is back in sync.
  5. Check display scaling and taskbar settings, which are part of the documented node configuration: scaling must be 100% on all nodes, and on ATLAS-01 to ATLAS-04 the taskbar sits at the top and auto-hides. A restored or reimaged node that differs here will render incorrectly.