View Full Version : Lighting

03 March 2003, 10:16 PM
After reading buch of posts I have a few questions-
What are lightlists?
What are area lights and how to use or fake it.
Tube lights?
"Real world" light falloff.
Subsurface Scattering.
Can AM do these and if it cant how can we fake it and is it worth bugging Hash over this?

03 March 2003, 09:25 AM
I'll have a go at those I'm confident of... But you can do google searches on this stuff or check your local library on theatre or film lighting.

Light lists are lights you drop into a choreograghy file that you wish to light one model only. Think of being in a dark space with objects all around - you create light lists to light only one object in that space. Useful to highlight objects of get a feel for depth with unwanted light hitting other objects.

Subsurface scattering is one of those things that is forming the new "holy grail" to try recreating the slightly waxy look of human flesh. There's always something else that users want to get that "real human look" instead of the traditional fibreglass model effect... in the real world any manufacturer will encourage buyers or users to keep coming back and buying the next model or upgrade which promises that much better whizz or effect..

I'm on weak ground now but area is like ambient lighting - you're not really after spotlight effects but you can set a general light level for a scene. Thus fall-off is about how the quality and "strength" of light gets faded the further away from the light source you are.

As to bugging Hash about them - some time ago the general consensus was get what's there working really well then add fancy extras. Light lists are there and work really well. Some of the others you mention can be achieved by clever manipulation of the existing light types.

As a non-lighting person I await correction happily.

03 March 2003, 10:33 PM
Area light are just what they sound like. Whereas standard point lights emit light in all directions from an infinitely small point, area lights emit light evenly from the entire surface of an area. As a result point lights suffer from very sharp constant shadows, while area lights produce much softer realistic shadows, with falloff of intensity - shadows are sherp and dark near the object, but blur out over distance like real lights do. Tube lights are just a variation on the area light - the area being the surface of a tube. Good for simulating those big fluorescent bulbs.
Up to version 10 Hash had area shadows - you would increase the rays cast to produce the effects of an area shadow - though not the same illumination effects. Though the results were a bit grainy at times, it was one of the best features of lights in hash, but for some unknown reason has gone bye bye.
Sub-surface scattering or SSS, is the new favourite trick of those obsessed with recreating reality
:shrug: . It's basically a fancy form of translucency - instead of just bouncing off the surface of an object the light bounces around inside the surface and is scattered in different directions. Put your hand over a torch and you'll see it in real life. Looks nice, if you're into that tye of thing. Don't expect it in hash soon though.
Real world fall off is just how the light intensity decays over distance - inverse squared or something like that. I'm not sure how light decays in Hash.
Hope that helps a bit.

Ciaran Moloney

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