DDGI overshadow or overlit problem

Graphics
#1

I am testing Flax’s DDGI with a simple scene with sphere and cubes.
However, I find that in some position or angle (especially when an object is close to another) the light probe will go black or white .

And this will make an overshadowed (black) color on the object

ddgi_overshadow.PNG
ddgi_overshadow.PNG1512×996 54.9 KB

Or, make an overlit color (as if there is a point light in the spot eventhough there is none)

ddgi_overlit.PNG
ddgi_overlit.PNG1514×971 69.9 KB

My question is,

  • Is this normal and there are some ways I can do to fix this?
  • Or is this the limitation of DDGI algorithm? I’m not familiar with DDGI altorithm,
    but the problem looks similiar with the disadvantages of “Virtual Point Lights (VPL)” or “Reflective Shadow Map(RSM)” algorithm.
  • Or simply is this a bug inside DDGI implementation in Flax?

Thanks.

#2

Tested with the TechDemo 2022

This also happens in the tech demo, so I guess this is the intended result??

#3

I think that it is not intended, but mafi has plans in 1.8 for improving DDGI in many ways.

#4

Hey, thanks for replying.
I hope this problem is acknowledged and hopefully there will be some fix, or at least adding a few tweaking parameters in DDGI settings to deal with these problems.
Because personally I think DDGI is awesome, and one of the reason Flax Engine can actually compete with other modern Game Engines.

I also posted a Github issue:

#5

Yeah, I agree. DDGI is quite nice especially when its working correctly.

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