Correct. An SDF is basically an acceleration structure for an "omnidirectional" raycast. A "sphere-cast", if you will. If you are extra careful, you can also ap

Correct. An SDF is basically an acceleration structure for an "omnidirectional" raycast. A "sphere-cast", if you will. If you are extra careful, you can also approximate a cone trace. Unreal Engine 4 has used it as a way of doing shadows for objects that don't animate for a long time [0]. But it's now a pretty standard staple of VFX and other sorts of industries to do a cheap approximate raycast on the GPU. Lumen simply uses the same data structure to accelerate bounce lighting cone tracing. [0] http://advances.realtimerendering.com/s2015/DynamicOcclusionWithSignedDistanceFields.pdf http://advances.realtimerendering.com/s2015/DynamicOcclusion...