Monday, July 21, 2014

A rant against light-linking

The title says it all : I don't like light-linking. I actually hate it.

I have banned them. Some artists were chocked when I've told them that.
You may think it's a weird idea, but let me explain why.

I've used them. A lot. At the beginning of my career, not only we used light-linking, but not only per object, but per shader.
It was a nightmare.

Unavoidable at that time to keep the render times manageable, but in the process, our artist time was going through the roof.
When you start spending more time fixing a scene or just understand it than lighting it, something is wrong.
When half the tools you are using on a daily basis are coded to ease that task instead of helping you create a better work, something is wrong.

It was a long time ago (10 years worth a hundred in VFX), but I still see the infamous light-linking used on production.

On top of all the problem light-linking can bring inside your application (Maya is a perfect example of a really bad implementation), it raises many other problems.

1. It makes the scene insanely complex.

Light linking is not obvious. It's not something you can realize when you see all the lights in the view-port.
It can also be tedious to check what is affecting who.

And if you are giving your lighting scene to another artist for a shot variation, or just because you are going on vacation, and assuming it doesn't brake in the process, how much time is required by that artist to understand the relations you have created?

2. It doesn't make sense.

A light not affecting a single object or only a group of object is not logical and goes against common sense.

3. It makes the lighting, and the lighting task, more complex.

Starting using light-linking makes you use more lights, and more lighting cheats. I will get to that.