Using Unity reflection probes to light your scene. IBL (Image Based Lighting)

IBL is a cheap way to get lighting that immerses objects in the scene.
In real life IBL are captured with a chrome sphere and a 50% gray matt sphere.
In 3D we can simulate this by using reflection probes and MipMap.
The shader can then use mipmap=0 in camera reference for the specular component and mipmap=10 in world reference to add to the albedo.
This produces an effect very similar to diffuse lighting seen in global illumination (GI) and the cost is very small.