参考https://developer.nvidia.com/blog/introducing-ray-tracing-in-unreal-engine-4/
unreal的rt功能比传统功能比如gi ao reflection要好,注意:当开启rtgi的时候lpv会失效,虽然在unreal postprocessvolume界面上两者可以同时开启。
LPV is another edge case. Light Propagation Volumes are a technique to use voxels to simulate the color bounce of GI. Like many rasterized methods of rendering, it is approximate and often low-resolution. With ray tracing on, LPV does not work. This won’t affect most projects, as most games probably don’t use the LPV. Going forward, there will be better GI solutions specifically for ray tracing.