How To Fix The Wrong Light Falloff And Clipped Highlights

Rev2019

I think most have the same issue.

You try to lit up a room but to get decent light in the room you must increase the lightsources to insane levels.

Or you need to add extra fake light to lit up what ever you want to lit up because the light in the room isnt enough.

This lihgtsource increasement also causes highlights to clip on or near the lightsources.

 

The main problem here is the wrong and too short light falloff.

i have read about this problem before so its not new but this is the first time i really test it and compare.

 

To fix this issue simply select everything in the scene then press "create"  "new group"

Then in the paramters tab with the group selected,set scale to 20% and start to create renderers with much better light and dynamic range.

the only drawback to this is that camera movements gets a little bit off.

 

i post one iray preview that shows one photometric lightsource with scene scale at default 100% and one other with the scene scaled down to 20%

 

Richard Haseltine

The light falls off as inverse square, which is physically correct. Instead of brigthening the light, by turning up luminance or shrinking the room, adjust the Tonemapping settings to cotnrol exposure and gamma so that you get the look you want with a plausible light. Adding Ghost Lights is mainly a tool to help convergence by fggetting enough light into inaccessible areas.

Rev2019

adjusting gamma and highlight clipping in the rendering settings will not fix the short traveled light.

picture only gets flat and washed out if you reduce highlight clipping.

one question

have you tried this method or are you just asuming?

 

also ghostlights or any surface that emits light is bad at rendering highlights.

you need photometric lights

Richard Haseltine

Shrinking the scene is the same as increasing brightness, if you don't like the results of adjusting tone mapping (not just gamma) then the lights need rethinking. Iray falls off physically, it isn't a set distance or cut-off.