Bouncelighting - faking/enhancing radiosity

[Artesia]

Okay, just so you know my background, ive been studying (as a student not professional) 3d art for about 7 years now, my primary app is 3dsmax (I have been bribed to make custom models for games before but I'm not entirely sure what the requirements for source are, in terms of formats etc.) I also know some maya, Zbrush, Vue, random other stuff.

Okay so in 3d, radiosity generally takes longer to calculate and requires additional software. But there are ways to fake it without using them. or you can 'enhance' the radiosity using the same method.

keep in mind that I am faking all radiosity in the pictures using only 4 lights, hammer compiles radiosity, so this would only be used to enhance it.

I start with a basic room, 3 walls one with a window in it (thats right, no need for all walls in 3dsmax, stupid games )


next I add a spotlight (pure white) outside the windo to act like the sun, I should have used a directional light, but I already rendered the pictures so I dont care.


notice that there is no bouncelight, what isn't lit is 100% dark

next I add an omni light in the middle of the room it is 1/3 the brightness of the spotlight outside the window, and is pure white



now i'm adding the bouncelight, it sits above the hotspot where the light hits the floor, it is pure white and 1/2 the brightness of the spotlight, also notice it has attenuation, which means the farther you move from the light the dimmer it is, which can be played with in hammer.



and thats a bouncelight, but we've just been dealing with boring grey and white... now lets paint the floor red!



now this doesn't quite look right, anyone thats worn a red shirt in a room lit by harsh light knows about bleedlight, so lets change the bouncelight color to red!



now you can see the red bleeding onto the other walls. lets try something and paint the other wall blue.



now the bleeding is more subtle, but we're dealing with another harsh color so we need a new light, not so much for bouncelight, more for a bleedlight. so im making a blue light, half the brightness of the red light, and a bit higher on the wall where the red light would bounce to.



and there you have it, 4 lights to simulate bounce light. now keep in mind that since source calculates radiosity, you only need 1 light to see, and can add the bouncelight to tweak. Also I only used 2 bouncelights because of the 2 wall colors.

anyways, if this was helpful I could always write more stuff for you guys... let me know

[Corion]

Nice post. :0)

I've seen lighting techniques like this in games before, but you don't seem to need it as much in Hammer.

Not really what I was talking about, but nice nonetheless. :0p

I wish I had 3d modelling experience. :0(

[Artesia]

this post was in response to corion's post in which he's playing with lighting... one sec I'll post a hammer use of bouncelight

[Artesia]

ok this is a slightly different use of this, but im basically taking stuff ive done in the past and figuring out how to do it in hammer

start witha room, with a recessed panel, inside is the texture lights/white001. im using the default lights.rad settings for this texture



adding a light 16 units outside the hole, full white, brightness 200



adding env_lightglow at the same loc as the light, vertical and horizontal size are 48, min distance -1, max distance 96



anyways, hope this is also useful to someone

[msleeper]

Bouncelight does infact work in VRAD. Make your scenario map above, use white and/or plain colored walls, but make the floor one of the orange Dev textures, and be ready to puke.

[Artesia]

I know it works, if you read the post I say that

I was just showing how you can do it manually to extend bounces...

in standard computer graphics, there is a limit to how bright you can make something which is 255 255 255 or white. HDRI allows you to go beyond this, but that is for reflections mainly. So if you have a really bright light in that little hole there, and its shining on the wall, but you dont want it bright enough to clip the hole itself to white, you can turn the light down, and fake a bouncelight to keep the illusion of a bright light.