Distance Fields

What are they?

Distance fields also known as Signed Distance Fields or Signed Distance Functions are images/fields etc where each location contains the distance to the nearest edge, surface or seed location. They can be 3D or 2D with the only difference being how they're calculated and stored.

They're used in many different places, for example, Unreal Engine has been using 3D Distance Fields since Unreal Engine 4 for some of their shadowing techniques. They use the distance fields of meshes for this. More recently in Unreal Engine 5, Lumen uses these same distance fields to achieve its realistic lighting at real-time thanks to the performance gains distance fields provide over normal ray marching.