What are light probes?
Lightmaps cover the environment, but if you just bake a lightmap, dynamic objects won't be affected. You also need light probes!
Light probes are points in space that capture an image of the surrounding lighting from all directions. When there are enough probes to create a tetrahedron between them, that space will affect the dynamic objects inside it and send them the data from the nearest probes, blending between the points of the tetrahedron.
Light probes have a major impact on how dynamic objects receive the lighting from your scene. Because of this, getting their placement wrong will make dynamic objects look totally wrong. However, light probes are *extremely* cheap. You can have tens of thousands of baked light probes in a single scene with practically no performance impact. Conversely, placing tens of thousands of probes would be awfully tedious, which is why it's recommended to use tools to do the job for you.
In this case, I recommend reading the Unity page on light probes to get an understanding of how they work and should be placed.
2 Comments
I'd like to expand on this guide later, but if your browser supports translation from Japanese to English I recommend checking whiteflare's guide here https://esa-pages.io/p/sharing/15655/posts/39/dbe60d6531f8c74e0811.html for more information.
Yeah, the Unity page is great for this!
After seeing how Overwatch has light probes everywhere I stopped trying to place them perfectly. As you said, even having tens of thousands is OK 😎