Realtime Distance Field Global Illumination Came Back!

Hi Folks, I have been reviewing the source code of Unreal for a few hours. I realized something interesting and wanted to share because there are so many people who are waiting for a Realtime GI solution. It was about Distance Filed Global Illumination. DFGI was a Dynamic Global Illumination technology for open world games on 4.8. After a few version, Epic removed this feature for some reason and left us alone with the LPV. And today I realized that Epic actually didn’t remove it, just disabled and closed the access. I had a look at GitHub history and as I understand Epic developed it slightly. I wanted to try my chance, opened access and compiled the engine. The Result is Distance Field Global Illumination and Heightfield Global Illumination came back to 4.19.2! Also, I did a little test and DFGI performance is amazing! At 4.8, DFGI was very expensive but my tests on 4.19.2 it only costs 1-1.1 ms and HFGI cost is around 0.1 ms on GTX 980 Ti! I will keep doing tests.

This sounds awesome, I’d be curious to see some screenshots if you happen to get any.

I’m doing performance tests now. After that, I can share some screenshots as soon as possible.

UPDATE: I think DFAO implementation not ready or not optimized yet for combining with DFGI. Because activating it causes a huge performance drop. In my case: 5.3ms (188 fps) to 18 ms (55 fps). But I have many other methods such as SSAO, HBAO+ and VXAO. I will test with these.

Why would you activate both, DFGI is just the same thing as DFAO but with sampling light bounces as well.

The drop would be trying to double up doing the same calculations for no benefit, straining the same parts of the hardware twice would probably explain the huge drop.

Massive what is it you did to get grant access to in code?

Any new on this? Whould like to see how it looks

Yeah not sure if it’s cause of a version difference however, forcing the DFGI/Heightmap GI options via engine causes the editor to crash when creating distance meshes.