In a simple exterior scene using vray sun/sky I want to have independent control over the appearance of the vray sky. I am using two dome lights each with the vray sky instanced. I want one dome light to control the overall lighting and the other dome light to adjust the brightness/exposure of the vray sky.
I make one of the dome lights invisible, this one controls the scene light. The one that is visible controls the sky brightness/exposure. For both dome lights I leave all other settings at default (affect diffuse, specular, reflections all checked).
Then using Lightmix I adjust the value of the visible dome light to adjust the brightness of the sky, independent from adjusting the lighting of the rest of the scene
This seems to work well but I’m unsure if I’m using the recommended setup to achieve this independent control over the sky?
Hi, thanks for posting. There is nothing wrong with such a setup. It will work ad you’ve already confirmed but it will increase render time. Using the VRaySky trough a Dome Light is more expensive than using it in the environment slot. It is more or less as if you have two Dome Lights with hdri textures.
Thank you Vladimir! If I understand correctly… independent control of the sky exposure/brightness it would then work in lightmix by adjusting the value of the environment.
I’m not sure that setup is correct actually. But someone please correct me.
If you just want to have the appearance of the sky change then you need to have it set up like this:
2 x VrayDomeLight with instance VraySky: how you’ve set it up at this moment.
1 Domelight set to invisible, all the rest to default, again like you have set it up.
1 Domelight set to Visible, but all the rest: cast shadows, affect diffuse, reflection and specular is set to off.
If you don’t do it like this, the domelight that controls the look of your sky will also contribute (on top of the other domelight) to lighting, reflections etc.
You can even have another domelight if you want to control your reflections independently, and then you disable them in the invisible domelight, and create another one where everything is disable except reflections, so then you have ultimate control over, lighting, reflections and look.
Hmmm. That’s what I initially thought. I’m experimenting with that now and with the visible dome light checking/un checking those cast shadows, affect diffuse, specular, reflection options does not seem to have any affect on the rest of the scene lighting.
Adjusting the invisible dome light value in Lightmix affects the overall scene lighting but has no affect on the sky. Adjusting the visible dome light value in Lightmix only affects the sky and has no affect on the rest of the scene lighting.
Not sure it’s relevant but what seems to look best is if in Lightmix I have the invisible dome at 0.6 and the sky at 0.4.
Agreed…doesn’t make any sense to have 2 super bright lights affecting everything like that.
Essentially all that one dome is is the background and so independent of all else 
I prefer to keep things simple and use elements in post-production to fine-tune. Otherwise, it’ll drive you crazy.
Agreed and I do the same quite often. this time I used the vray clouds and got a nice looking sky that I wanted to use. I am posting that in the gallery section now.
Although you can still have a setup that works in the VFB that is simple, or it just being more immediate than post elements, and is easy to control in all sorts of ways, as in the attached.
Good to have options I guess
BASIC EXTERIOR SKY SETUP.rar (61.9 KB)