VXGI shadow too dark

Hi everyone

I’m trying UE with VXGI recently and build a simple scene as below:

My question is why the shadow so dark in red circle

There are one direction light and one emissive material in the scene
11dc50950a60157d174b45c0f4e62bb70fb967aa.jpeg

My set :
Directional Light Intensity =10
Emissive Material Emissive =30
r.XGI.MapSize 128
r.VXGI.MultiBounceEnable 1
1a08439cd982d38595e8e70a02f511db6e16174a.jpeg

Please advise me how to make the shadow lighter but do not effect another area

Thanks

It’s been a while since I’ve used VXGI but from what I recall:

-Use the VXGI anchor thingy where you have the focus of your scene (so it doesn’t voxelize your scene based on closest to camera)
-Tracing Sparsity 4 is a bit low. 2 is default iirc
-Don’t use overboost on your indirect lighting intensity. Leave it at 1
-Make sure you don’t have HBAO or SSAO on when tweaking your VXGI AO (tweak VXGI first, then add SSAO later to complement)
-Tracing step 0.5 is default but 0.1 gives optimal results (and will completely destroy what fps you had left as a nice bonus)
-Play with Opacity Correction slider and offset sliders (the first has a major impact on your AO)
-Enable VXGI specular
-Use proper materials

Note: With emissive surfaces and VXGI just about anything goes.
If you want accurate lighting I highly recommend swapping anything big with an emissive surface for a proper light.

Hope that helps!

Thanks very much for your reply, Chesire.
I try to following your step and a have some questions

-Use the VXGI anchor thingy where you have the focus of your scene
I cant find this parameter in Camera details,where can I find it?

-Make sure you don’t have HBAO or SSAO on when tweaking your VXGI AO
HBAO is disable,but I cant find SSAO in console or PostProcessVolume

-Play with Opacity Correction slider and offset sliders
Where can I find Opacity Correction slider

-swapping anything big with an emissive surface for a proper light
I’m not sure what’s your meaning

Thank you again.