An IES file is the measurement of the distribution of light (intensity) stored in ASCII format. IES profiles are useful for creating life-like lighting, as they can represent the physical distribution of light from any light source.
Here is an example of lights with different IES profiles (From Maya Zest free IES files):
Any of these profiles can be attached to a mesh light in Reality, and this will make the light behave according to the IES profile. Yes, that means you can turn a little mesh light plane into a round spot light with a well-defined light cone!
IES profiles make this possible to control the light cones and light spill to a degree that is not possible using standard mesh lights and it will take your renders to the next level.
In the tutorial, I show how to make a rather simplistic (primitive-only) simulation of a flashlight in an otherwise low-light scene with a bunch of low-emissive light sources. All to demonstrate the amount of control you can achieve with IES profiles:
As a bonus, I also show how to create the in-air visible light beam shown using a render effective localized fog/dust volume.
You can find the tutorial on the Reality forums by Clicking here!
We would love to see what you've created by using this tutorial!