Dome Light Proposal : Replace world slot for IBL with Dome Light Object
Hello,
I am a VFX/CG artist specialized in lighting / compositing, with experience using Pixar’s Renderman, Arnold, Vray, and even mentalRay ( back in the day ), and testing a lot of render engine for personal interest (Redshift, Octane, Maxwell, Guerilla to name a few)
I find very weird that I can't find any post about adding a Dome light to Blender. The issue is not about Cycle, but the fact that there is no Dome/Env light objects at all.
My understanding is that, in Blender, if I want to light a scene using an HDRI ( not matter the render engine used ), the only way is to plug the HDRI in the world slot, and I need to use a math node if I want to expose up or down this HDRI in blender. Using a world slot to do Image Based Lighting is, IMO, a very old way to approach environment lighting, and this should be addressed in Blender.
All render engines I know are now using dedicated dome/env lights, the world approach for IBL died with MentalRay and probably a old version of Vray as far I can remember. World slot is mostly used for global fog and background textures.
To explain why we need Dome Lights in modern lighting workflow, I will give some examples :
1 - Sky is a light : Environment lighting using an HDRI or a Physical sky should be treated as a light in the UI. Most renders use a dome light for the exposure and sampling control of this specific HDRI in the dome lights parameters. So its’ hard to create a plugin for blender, if blender ignores the fact that most render engine use dome lights.
2- Multiple dome lights for more control : A lighting workflow we use sometimes, is to actually have 3 HDRI contributing to the beauty, for example we have one dome light for the sky, one other dome light for the ground, and one for the sun ( keyed out from the sky HDRI ). This allow us to have more control other exposure of the ground / sun / sky while using image based lighting only, which is better than a directional light when using PBR shaders. We also use multi light AOVs, to be able to adjust those exposure in post>
3-Light linking : We sometime want to have a specific HDRI contributing to a specific piece of geo in one passe ( for example, eyes of a character, or windshield of a car ).
I take the liberty to open this topic because I did a lot of research and I was very surprised that I could not find any topic discussing this.
Please let me know if this request is out of topic in blender development forum.
Thank you for taking the time to read this.
10 Comments
Yes!
I am new to lighting. Can you atleast show some images.
This proposal would probably be great. There is a chance you could probably do that in blender but just a different implementation, maybe I am wrong.
* @johnpdelacruz26 * Hello, I added a thumbnail hoping it helps you better visualize the concept.
As you can see in the image, the Dome light is in the outliner like any other light, this means we can have multiple dome lights in the scene, we can rename those, light link them, and the parameters are consistent with the other type of lights.
* @Julian Horlaville * one day blender will have full featured Light Linking too. Perhaps. Hopefully. Eventually. At some point.
* @Julian Horlaville * I see. Thanks.
I was about to make almost the exact same proposal as you. It is really strange that with the refactor that cycles X brought, and with light linking on the to-do list, that this hasn't been addressed yet. It has always bugged me, it is a really strange design desition for a modern engine.
And it's not just important in VFX pipelines. I work in animation productions and we use at the very least two domes. Usually hair gets its own domelight to be able to fine tune the shadows and darkness of the character's hair.
This would be most helpful, and since it is treated as a light rather than an environment, you could do things like turn off shadows or add it to a collection which could disabled/enabled per view layer.
So something like this with more settings? {attachment 2020-07-25_19_14_15-Windowpng}
* @Anže * From what I can see, I assume it's a sphere object with a shader apply to it right ? It's really not the same than having a dedicated light for environment lighting, because, you need the dome light to optimise diffuse sampling based on the HDRI, and be able to connect with portal lights for interior lighting etc.
Also, you can't simply say, I want this monkey and the ground to trace this dome light, but another monkey would trace a different dome light. ( that mean the shadows of monkey 1 and 2 on the plane would be using dome light 1, but the shadow of monkey 1 on monkey 2 would use dome light 2, and of course monkey 2 would trace dome light. Unfortunately, no hacks in blender can come close to what we can do with a dome light object in other package.
* @Julian Horlaville * Well yeah as I said: Something like this with more settings. The more settings means optimized sampling (your first paragraph) and being able to light link not only lights but objects too (your second paragraph).