Scaling lights

[Guest]

If lights are scaled does this screw with the intensity or any other settings? I have a studio set up that is for larger objects however some times I need to render slightly smaller objects which require smaller lights and backdrop. Rather than changing all the dimensions etc it would be easier to just scale it down in one hit.

Cheers

[vlado]

I remember there used to be issues with scaling lights; some them we fixed, but there might still be odd things going.

Best regards,
Vlado

[Morbid Angel]

If lights are scaled does this screw with the intensity or any other settings? I have a studio set up that is for larger objects however some times I need to render slightly smaller objects which require smaller lights and backdrop. Rather than changing all the dimensions etc it would be easier to just scale it down in one hit.

Cheers

Just so I don't second guess my self or my artists, I tell every one to use the UV values in the lights and leave scale at default.

[Deflaminis]

I've noticed it's not really a problem until it gets to about 500% or so, and seems scene specific. Just about any renderer I've used seems to have problems with scaling lights though.

I also tell my people and students not to scale the lights, force of habit I guess.

[Morbid Angel]

and if they do - slap!

[Guest]

Thanks for the help guys. I might do a few tests and see if there are any noticeable results.

[michaelwbell]

If scaling lights is causing issues, You could use Dummys...
put dummys in the position of all current lights,
constrain light position to their respective dummys
link dummys to a master dummy in the centre of your key object, then just scale the master dummy each time as needed

[Guest]

Done some quick tests and it seems scaling up makes lights darker and scaling down also seems to darken the lights/exposure controls. Here is the test with a small studio at 100% and then scaled up using the scale tool (just grabbed everything and scaled it) to 1000%.



Here is a large scene at 100% and then scaled down to 10%.

[vlado]

Yes, like all the guys pointed out above, scaling the lights may lead to issues. I believe we fixed some of them at one point, but it's a tricky thing.

Best regards,
Vlado

[cheerioboy]

I always thought it made sense when the lights got brighter through scaling. You're making it a larger light, thus more surface to emit light. Maybe since the light's own parameters change it starts to get confusing.
Dunno. But I've always scaled as well as using the light controls without it bothering my workflow, it just needs to look right!

Sounds similar to making primitives and scaling them vs using the spinners on the right to adjust size.

[vlado]

I always thought it made sense when the lights got brighter through scaling. You're making it a larger light, thus more surface to emit light.

Yes, but - the objects that are illuminated move away from the light, and this should exactly cancel out the increase in the emitted light.

Best regards,
Vlado

[airstyle]

I always thought it made sense when the lights got brighter through scaling. You're making it a larger light, thus more surface to emit light. Maybe since the light's own parameters change it starts to get confusing.
Dunno.

You're right man, that's what I've been taught to believe about physically-correct light surfaces - but in this instance the OP is trying to scale the lights and the whole scene by exactly the same amount; this means due to also physically-correct light decay, light rays should reach the points on the surfaces at the same angle and intensity.

My guess is the problem might lie in the GI solution, as if you look at the OP's posted images the reflections of the area lights are quite similar across the scaling tests, whereas the total perceived light in the scene blows out somewhat exponentially.

[Guest]

You're right man, that's what I've been taught to believe about physically-correct light surfaces - but in this instance the OP is trying to scale the lights and the whole scene by exactly the same amount; this means due to also physically-correct light decay, light rays should reach the points on the surfaces at the same angle and intensity.

My guess is the problem might lie in the GI solution, as if you look at the OP's posted images the reflections of the area lights are quite similar across the scaling tests, whereas the total perceived light in the scene blows out somewhat exponentially.

This is my theory as well, I would have thought that because everything is being scaled the intensity should not change.

[vlado]

No, it's not the GI; simply some calculations in the lights do not take into account the scale of the transformation matrix.

Best regards,
Vlado

[Guest]

No, it's not the GI; simply some calculations in the lights do not take into account the scale of the transformation matrix.

Best regards,
Vlado

Can they? Is it possible in the future? Or is this how it is, which is fine as I avoid scaling in most cases anyway. Just wanted a quick win for these studio set ups I have.