Cita:
Lumen is a hybrid tracing pipeline that uses Software Ray Tracing. It traces against the depth buffer first, which we call Screen Traces, then it traces against the distance field and applies lighting to ray hits with the Surface Cache. Lumen takes any given scene and renders a very low-resolution model of it. Light behavior in this low-res model is then recorded, and a rough lightmap is created. This lightmap is then used to trace the path taken by every ray in the scene. Then, the output lighting is upscaled and displayed as a cube map. The engine does all the heavy lifting, and Lumen does not affect the assets gathered in a scene.
Thus, it is an innovative solution to the highly intensive hardware-accelerated ray tracing method. Because the Lumen method uses upscaling, flickering may occur at high resolutions. Ray Tracing does not have this drawback, as it does not use upscaling. Lumen also provides Hardware Ray Tracing. It supports a range of geometry types by tracing against triangles and evaluating lighting where the rays hit. Hardware Ray Tracing is more accurate but more expensive.
Entonces cuando tenes el motor más importante de todos apuntando para ese lado, lo que está puesto en discusión en este thread no tiene tanto sentido (el argumento de que es un engaño), porque no hay chance de que ray tracing y path tracing no estén sobre la mesa en presente y futuro.