Exposure slider and scale compensation for lights

[dgruwier]

First request is an exposure slider to go right below the intensity slider, so the total output of the light is Intensity*2^Exposure . That way you can adjust the brightness of the light in stops, which makes it makes it so much more intuitive to fine tune your lighting, especially when your lights have crazy values like 32024000 and you want to make it half as bright without breaking out the calculator. It also lets you directly copy values from exposure sliders in the frame buffer and post software.

The second is a checkbox to preserve the intensity when scaling it up or down, so that scaling doesn't affect the brightness of the object being illuminated, only the highlight size and the softness of the shadow it casts. The Size Multiplier in VRaySun has this property, it changes the softness of the light, but not the overall illuminance. I think the formula is the same as exposure, so Intensity * Size². There are some design choices to be made here to make it useful, because ideally you'd be able to change your mind half way through setting up your lights, and enable the feature without losing your current values.

I have to things on my wishlist for lights. I have a script to create my own VRayLight preset that has these options as attributes, but it would be great to have them as native options

[Muhammed_Hamed]

+1 here
Using both with Arnold lights natively, they are quite handy
would be nice to have them native to Vray lights.

[vlado]

For the scaling, you can choose the light intensity to be specified in total light power units (like lumen) in which case scaling the light will not affect the illumination that it produces.

Exposure has been requested before, but I'm reluctant to introduce two controls for the same thing. We'll see though.

Best regards,
Vlado

[dgruwier]

Thanks Vlado, that is a neat trick with lumen. That covers the scale thing as far as I'm concerned.

As for exposure, I can see why you're reluctant to muddy up the UI like that, but it really is just super convenient to have a multiplier that relates intuitively to the brightness of the image. On top of that it carries a few specific workflow improvements, with it you can:

• select multiple lights and tweak the exposure by the same value to get the same reduction or increase in brightness across all of them
• copy values between other filters and attributes that work in stops (You can dial in the exposure in the VFB, then just copy that value directly to the scene lights to make it permanent)
• tweak the brightness of lights that are keyframed or controlled by expressions

The distance attribute on environment fog and the amount sliders for VRayMtl come to mind as other examples of having these extra controls for convenience.

[francomanko]

Can i ask what situation you had where the lights had values like 32024000?

[dgruwier]

Small light very far away as a sun. Might have added a few zeroes, but it was just an example of a number that’s not easy to manipulate by percentages in your head.