Play 3D Content with 2 Projectors

Last updated 5 May 2026

Backstage supports stereo 3D output for two-projector setups where one projector shows the left eye and the other shows the right eye. The stereo rendering is frame-sequential — Backstage renders each frame twice, once per eye.

Before you start

  • Two projectors are connected to the same server
  • Your 3D content is prepared (see content format options below)

Content formats

Option A — Two separate files (recommended): Import a left eye file and a right eye file separately, then combine them into a Multi-Channel Asset with Channel 1 = left eye and Channel 2 = right eye.

Option B — Single top-bottom encoded file: Import a single video where the top half is the left eye and the bottom half is the right eye. Enable the Stereo Top-Bottom flag on the asset in the Inspector.

Steps

1. Configure the projectors

Select the first projector in the scene hierarchy. In the Inspector: enable Stereo Projector and set Stereo Channel to 1 (left eye).

Select the second projector. Enable Stereo Projector and set Stereo Channel to 2 (right eye).

2. Assign content to the surface

Drag the Multi-Channel Asset onto the projection surface and confirm the Create Sequencers? dialog. Backstage routes Channel 1 to Stereo Channel 1 and Channel 2 to Stereo Channel 2 automatically.

3. Enable stereo on the output (active 3D only)

Open the Outputs window and select the output slot. Check Enable Stereo Output and set Stereo Mode:

Mode

When to use

WhiteLine

Frame-sequential with external 3D sync hardware — most common for professional two-projector installs

Active3dStereo

Projectors with built-in active stereo support

Side-by-Side / Top-Bottom / Interleaved

Passive glasses setups with encoded content

4. Connect the sync hardware (active 3D only)

For WhiteLine mode, the sync pulse is embedded in the output frames — a horizontal line at 1/3 height on left-eye frames and 2/3 height on right-eye frames. Connect the sync distributor to your projector controller per its documentation.

Common Mistakes

  • Both projectors show the same eye — Stereo Channel is not configured per projector. One must be set to Channel 1 and the other to Channel 2.

  • 3D sync distributor receives no signal — Stereo Output is not enabled in the Outputs window, or the Stereo Mode is not set to WhiteLine.

  • Left and right eyes appear swapped — swap the Stereo Channel assignments between the two projectors.

Tips

  • Active stereo is configured in the output slot — enable it on each output that feeds stereo projectors.

  • Passive stereo is managed through the Projector Properties (left eye projector, right eye projector).

  • For passive glasses setups using Side-by-Side or Top-Bottom modes, no external sync hardware is needed.

Play 1 Video on Multiple Displays — play one video on multiple displays

Installation Scenarios — all installation scenarios