best way to get even interior lighting w/ radiosity??

[edub]

I'm doing a large retail store interior with multiple downlights in the ceiling.

 

I am trying to get a nicely lit interior w/ radiosity, but WITHOUT having a light for each fixture.

 

I've been experimenting with area lights (one large covering the whole ceiling, or multiple smaller), but I can't seem avoid washing out the ceiling because they are double-sided (area lights emit from both sides?)

 

I've also experimented with doing a first-pass radiosity without the ceiling on (using only a sky object as a light source), then using that solution to render a second pass with the ceiling turned back on. It works pretty well (i.e. FAST+nice shadows), but the ceiling doesn't look quite right... I guess, since it's not part of the radiosity calculation.

 

If I leave the ceiling on, only the light entering through the storefront is used. Since the store is quite deep (100ft), it becomes dark further in).

 

My question, for those in the know:

 

What kind of light sources do I use to evenly light a large interior space (30'x100' deep), using radiosity??

 

-spot lights?

 

-omni lights?

 

-area lights?

 

-sky object (with ceiling off)?

 

which level should radiosity strength be set to?

 

I would appreciate any help or tips

 

thanks!

[William Alexander]

It's possible to use an object or selection based material assignment with a luminance channel to light your scene.

 

It may give that "general' illumination effect, your looking for. Use some strategically placed lights to cast scene specific shadows and fairly high min/max res settings.

 

WDA

[Ernest Burden III]

It's possible to use an object or selection based material assignment with a luminance channel to light your scene.

 

That's a good idea. I have been wondering about any differences between a 'luminance' channel of white and an area light of equal size. I guess you might want to put a non-emmiting material on the backsides of the ceiling polys.

 

I'm currently doing a restaurant with many downlights. I am pondering the same issues you are. My first step has been to creat a bunch of round polys to put in all light locations so you will SEE the light location, whether or not it has an actual light.

[STRAT]

It's possible to use an object or selection based material assignment with a luminance channel to light your scene.

 

WDA

 

which is, of course, the basic concept behind image based lighting

(or object based lighting if you prefer. exactly the same as IBL, but without an actual image)

 

Ernest, the only problem with putting in 'invisible' illuminance objects to GI light the scene is that they require a heck of a lot more samples to make smooth results.

 

IBL always requires more samples. As WDA says, insert some omnis around, this will help the gi effect and take some of the load off the real gi casting objects.

[Ernest Burden III]

OK, let's assume we are going to use a bunch of downlights, as spec'ed for our space. How to control them so they provide lighting and radisity but do not turn the project into a massive rendertime.

 

I know Stephen you advocate using fill omnis. But for the actual spots, how do we set them up? I have been experimenting. It makes the most sense to use inverse/sq falloff. Is it best to use the regular falloff system and drag the visual falloff indicator just past the floor, or use the near/far numbers instead?

[STRAT]

OK, let's assume we are going to use a bunch of downlights, as spec'ed for our space. How to control them so they provide lighting and radisity but do not turn the project into a massive rendertime.

 

I know Stephen you advocate using fill omnis. But for the actual spots, how do we set them up? I have been experimenting. It makes the most sense to use inverse/sq falloff. Is it best to use the regular falloff system and drag the visual falloff indicator just past the floor, or use the near/far numbers instead?

 

if i've got, for example, a wall with a line of down lighting spots to show, i'll first set up 1 original spot, then instance all the rest so i only got to fiddle with one. and then it depends. sometimes i'll use an inverse/sq fall off, but more often than not i'll use a standard near/far clip falloff.

then if then dont happen to be shining on anything important, i'll turn the shadow map samples down real low. and i mean real low.

 

but it's a case of experimenting and playing for individual scenes. i never use area lights/shads unless absolutely needs be. hate using hi shadow map samples. dont much use volumetrics. but often use visible light. this doesnt slow things down too much.

 

even though c4d has the beauty of simplicity for the user interface, it does approach max's useless complexity sometimes, for example, fall off types - why have 8??? ok, those 8 may be good in different circumstances, but 99% of us 99% of the time will never need 8!!

[edub]

My first step has been to creat a bunch of round polys to put in all light locations so you will SEE the light location, whether or not it has an actual light.

 

yeah, I've done that too..

 

in that first example in the image, would it require the whole ceiling to be seen as emitting the light - or is there a way to emit the light from the ceiling, without it looking like it glows.

 

Maybe this is what the rest of the discussion is about, but I got kinda lost (little dude here).

 

Thanks