Infected by Immersion
Glossary /

Cross-Reflectance

The light bounce problem unique to projection domes β€” where bright imagery washes out dark areas across the curved screen.

What is it?

Cross-reflectance (also called cross-bounce) occurs when projected light reflects off the dome surface back onto other parts of the dome. In a hemisphere, any bright area illuminates the entire interior β€” washing out blacks and reducing contrast.

The Physics

A dome screen must reflect light toward the audience. But the concave geometry means reflected light also bounces back onto the screen itself. This secondary reflection reaches the audience as unwanted ambient light, raising the black level and reducing the system contrast ratio to typically 10–14:1 (measured with a checkerboard pattern).

Mitigation Strategies

  • Darker screen coatings β€” reducing reflectance to 15–28% (at the cost of requiring brighter projectors)
  • Content design β€” avoiding large bright areas next to dark areas; why space content works well (mostly dark)
  • LED domes β€” eliminate the problem entirely by emitting light directly; achieving 100:1+ system contrast

As Kirk Johnson (Cosm) noted: "We always knew that to get the quality we needed, we had to get to an emissive technology β€” anytime you reflect light off a dome, you create cross-bounce."

See also: LED Dome β†’ Β· DLP Projection β†’ Β· Resolution β†’

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