Do we need ghost light?

James

Do we need ghost light?

In what kind of situation ghost light is better than already existing lights?

Richard Haseltine

Ghost lights, as originally conceived, alow the addition of light without any visible source and without showing in reflections - it's a way to get extra light into a scene to speed convergence without throwing out the main shadows and highlights.

James

No wonder my render time add up significantly after I add a light.
But I need it to get the reflection on the eye.

What does convergence means?
All I know it's on the render settings, usually set to 95 or 98%

Richard Haseltine

Convergence is a measure of how much each pixel varies between iterations - as it is hit by more light paths from more different directions it should narrow in on its final value; Iray has a threshold, determined by Render Quality, to decide when a pixel is near-enough final and when X% of the pixels have crossed that threshold it stops (by default).