Maximum Number of Lights

[Saerileth]

I'm wondering if someone could provide me with the hard limits of interior lighting, i.e. exactly how many of them can affect which objects before they cause flickering or popping in/out of view. I realise this topic has come up before a lot, but I can't find real details anywhere. Yes, I did read Bethesda's Lights and FX Tutorial, it's still rather vague for my tastes.

 

I think it's fairly well established that there can only be 4 shadow casting lights active at any one time (the engine starts disabling lights if there are more).

 

What about non-shadow lights? Is there a hard limit of how many can be in line of sight? How about the number of lights affecting a single object? I know there is a feature in the CK that is designed to debug lighting (Preferences -> Shaders -> # of lights), but I have yet to detect a pattern in what it tells me. Sometimes areas with three or more intersecting lights show up as fine (blue), other times two overlapping lights cause it to complain (red).

 

Another thing that is documented very poorly is the way fog and other ambient FX react to multiple light sources. In theory, they are supposed to pick up the colour of surrounding light sources, but I noticed they begin to flicker from one colour to another if there are too many lights present. Can they be affected by multiple light sources at all, or is this just an issue with overlapping lights?

 

If anyone could share their experiences with this (or link me to the article I missed that clears all this up) it'd be much appreciated. :)

[Kraeten]

Can't say I've ever heard or seen a hard number to go by where light limitations are concerned. Just the shadow casting lights as you already mentioned. As for fog, I believe the color can only be effected by one light. Never have I encountered an instance that might suggest otherwise.

 

Lighting has always been to me one of the biggest hurdles when designing interiors, so I can understand why you'd want as much information as possible. Sadly there isn't much to share. If your interior is very linear this resource could prove very useful to you. Just In Time Lighting Dynamic Scripts.

 

Unfortunately that resource has been of no use to me, since my own interior designs are too compact. Not linear enough. Hopefully it'll be useful for you. Best of luck.

[Saerileth]

Thanks for the reply! Yeah, lighting can cause quite a headache sometimes.

 

I already use JIT lighting, it's brilliant! Actually the area does not need to linear, it can handle multiple entrances/exits (just takes a bit more effort). Compact might be a problem, since the scripts do need some hallway space to work (no line of sight between rooms, and then some time for the lights to actually kick in). I did manage to "cheat" on the line of sight limitation by having a non-shadow casting light as a kind of "LOD" light in the distance, then simultaniosly fading it out while fading in a shadow version as the player gets closer. It's not perfect (there's still a slight flickering visible), but good enough for me.

 

I had a feeling fog might behave this way, which is a shame. Some of the low fogs are pretty large, it's very hard to have them hit by a single light source only. Is there some way to make an FX ignore some lights and focus on a particular one? I tried using emittance, but that makes the entire fx object take on the light's colour, which looks rather strange in dark corners.

 

On a related note, I guess it's worth mentioning that fog doesn't react to shadow lights at all.