What is the difference between Baked and Realtime Light?

Quick question:

What is the difference between a baked and a real time light??

I’ve noticed that it really doesn’t change that much in the game, except that depending on the light, it takes a hell of a time to bake it.

Baked light = heavy on RAM + HDD

Realtime light, espessially Global Illumination = heavy on GPU + (sometimes on CPU).

Baked light allows us to “wrap” objects in special “Lightmap” textures. Looks good until we decide to move one of such game objects. Because lightmaps are just textures, this immediately looks wrong.

The entire process of “light bake” would have to be started over again to remove this incorrect appearance, which would make us question, why not to dump light maps for good and use Real Time Global Illumination?

Well, it can be very expensive, and the player would need at least GTX460+ series graphics card (not uncommon but still), and GTX960+ for good-looking, beautiful realtime light. Or equivallent ATI of course.

Light maps on the other hand, just require us (devs) to compute all lighting before hand, storing it in Lightmap textures. Then, when the player enjoys the game, her computer would only have to draw several extra textures (which is a LOT quicker than computing real time global illumination)

hopefully this helps.


Baked is pre-computed and saves the engine a ton of processing power when dealing with shadows in a scene. So if you have a static light source and static objects (i.e. they don’t move), then use baking. But turn off auto in the Lighting settings, it’s just a pain.

Realtime is, exactly what it sounds like, lighting calculated in real time. It’s quite expensive and if your game isn’t all moving objects then you should learn how to bake and use light probes and reflection probes.

The link to the Unity tutorial that JesseFox provided will give you fuller details and show you how to use it.