Each level that you create is made up of all these Mesh Distance Fields for your placed Actors. When Mesh Distance Fields are generate, they are done so "offline"
using triangle raytracing that stores the results in a volume texture. Because of this, mesh distance field generation cannot be done at runtime. This method computes
the Signed Distance Field rays in all directions to find the nearest surface and stores that information.
You can visualize the Mesh Distance Fields that represent your scene by using the viewport and selecting Show > Visualize > Mesh Distance Fields.
Menu to Enable Visualization
Mesh Distance Field Visualization
Click images for full size.
When you see areas that are more white than gray, it means that many steps were needed to find the intersection of the mesh surface. Rays at grazing angles to surfaces took many more steps to intersect than would have
for a simpler mesh.