Photon OVRTX
Lights
Photon lights under the OVRTX engine — same units, different sampling.
Light types and units are shared with RTXPT → Lights — lumens, lux, nits, EV. What changes on OVRTX is how many lights stay cheap.
Light counts
RTXPT samples lights stochastically — hundreds are fine. OVRTX shades a bounded set per pixel:
| Tier | Count | Cost |
|---|---|---|
| Shadowed key lights | up to 8 | full shadows every frame |
| Cached contributors | up to 256 | shadows via radiance cache |
| Beyond that | unlimited | ambient pool, no individual shadows |
The engine promotes and demotes lights automatically by contribution; pin one with its Priority parameter when a cue depends on it.
Concert rigs: leave moving heads in the cached tier and pin only followspots. Promotion churn during a blackout snap is what the Priority pin exists for.
A DMX-driven light strobing at cache frequency defeats the cache — flag
fast-flicker fixtures with Animate → Realtime so they bypass it and
shade directly.