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View Full Version : What is the name for this lighting technique?

Greendogo
10-04-2009, 10:40 AM
Does anyone know what it's called when you have a light that subtracts from illumination instead of adding to it? I would call it negative lighting, but I can't find any examples searching anywhere with that term.

Also, would anyone have any example images that include a source of "negative light" in the scene (such as an orb or something) as well as any number of other sources of regular light (inside or outside the scene)?
playmesumch00ns
10-04-2009, 01:29 PM
Not really a technique so much as a hack that's sometimes useful. We just used to call it 'adding a negative light'. Used to be fairly common before GI became feasible. I don't think our light shaders even support it any more.

We do use it occasionally for faking shadowing on volumetrics since it's much, much faster than rendering deep shadows and you can sometimes get away with it. For instance, the large clouds of smoke in the great hall during the fireworks sequence in Harry Potter and the Order of the Phoenix definitely used negative lights rather than proper volumetric shadows.
Greendogo
10-04-2009, 02:03 PM
It's a shame it isn't supported anymore, I was going to use it as an element separate from usual lighting. I wanted to see how it could be used as a kind of black hole effect on the surrounding light.
soulburn3d
10-04-2009, 05:50 PM
It's a shame it isn't supported anymore

I think playmesumch00ns was referring to the company he's working for, I know the technique is still working in many different 3d apps, and I know a lot of studios that still use it. Sometimes it's just for subtle stuff, like making an area just slightly darker when a director asks for it.

- Neil
lazzhar
10-04-2009, 06:15 PM
There is a DVD tutorial (http://www.3drender.com/DVD1/maya_lighting_lights_shadows.htm) that talks about it.
wwswimming
10-05-2009, 02:21 PM
in one art design class i took the instructor used the term, "chiaroscuro".

the negative light is a chiaroscuro-izer.
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