VXGI implementation problems

[pervokpetr]

I still working with VXGI, for now I already implemented code for directional lights sun, spot and omni with respect to shadows, now VXGI will take into account this types of lights. But with this I faced with several weird problems and still can not find solution for it. Firstly I want to show you picture from NVidia example, this is that I want to see in game (but not reached yet)

https://drive.google.com/file/d/1Yg1KKqDMWToff9I1KxzQ6frG1x1xqIr7/view?usp=sharing

First picture with Gi turned off and second with GI on, as you can see there is significant differrence in lighting and VXGI simulate secondary lighting distribution.

What I have in game....

First problem - the secondary lighting not so strong, it looks weak and I have feeling that it computed incorrect, vxgi has a lot of parameters without clear explanations, so I hope I just did not setuped something correctly.

Second problem - I faced with it when I implemented sun lighing and shadows for vxgi - when I don't move camera, i.e. it static the picture looks stable, but when I move camera emiitance voxels and irradiance voxels are corrupted as final result. I did a lot of testing and checking and still can't understand problem. I know that it's derrived from villa camera algorithm, you should notice that when you move camera sun shadows shaking some time more after camera stop (you can check it in current version of hook). I did special data output to check that problem in ViewMatrix that represent camera position and direction, here on video you can see numbers of this matrix:

https://drive.google.com/file/d/1b57qwDC8_SbRtkdikiV_JufC6yLoY1rM/view?usp=sharing

We again should say "THANKS" to game developers for "quality work", they added some iertia to camera to make movements more smooth, but they do not created some good algorithm for this, such things require some tolerance parameters when inertia, movements and forces cuted in zero, to avoid such "shaking" for numbers due to precision of floating points. Due to all calculations in hook and shaders depends from this matrix, especially sun shadows, shaking appear for shadows to. Right now I reworked sun shadow algorithm to try disable this effect and I succeeded with this now now sun shadows don't shaking, ALTHOUGH this is not helped with emmitance and irradiance voxels they still corrupted somehow when camera moves:

https://drive.google.com/file/d/1Ck8X69SmMnz6JBj-CqSeqghZ7MGsSX4Y/view?usp=sharing

I'm a bit confused with this the algorithms for normal lighing and voxelized lighting use the same calculations - shadows looks stable when camera moves but voxels corrupted when camera moves , spot and omni lights do not have such problem, some light change in intensity of irradiance present, but not significant, so I believe that problem still in sun shadows, just don't understand where exactly.

Ant third problem - I faced with some weird halo around objects when they moves or camera moves, the documentation from NVidia clearly says that VXGI calculated for one frame back, so it always has one frame delay in results, but it have reprojection option to reduce this effect and NVidia example looks very stable and precise, I tryied implement my code as much possible closer to nvidia docs and examples but halo in my case too noticeble and for now I also can't understand what can cause such effect, here video:

https://drive.google.com/file/d/1DqKYcT2PcGlVP5_xhyK-ZqZwihmtuPex/view?usp=sharing

So this is situation for now, I thought that after first result all other will be question of couple weeks, but with deeping into vxgi I faced with more and more problems....

 

By the way, I'm missing so much for modsgarden.cc, typing such post on patreon will be literally hell, I tried on loverslab, but looks like I can't download or create something (but maybe I did something wrong) so I placed this info here and will give link to it on my patreon page, I hope it's OK, if not tell me.

[Driver]

Yeah, not only typing but reading long text is also hell in patreon, so I believe it'll be best bet both for you and for us Hook5 users, especially for the users who have been supporting hook5 project and have been participating in this forum, to communicate here. Welcome to KE man

[yodrizzle]

we can get very good rtgi now with reshade plug-in from pascal: Pascal Gilcher is creating the ReShade Ray Tracing shader (RTGI) and more | Patreon. I'm not sure you can improve on his work. Yes it's not free but it's very, very good now even with normal smoothing.

[Titanoboa Serpentes]

Thanks very much for the information on the progress of your work. For me it's totally fine that you post your progress here, but I can't, of course, speak in the name of other hook5 patreon users. But again many thanks for giving us information on your progress, and hopefully you will find a way to fix the errors that you described. The third problem looks a bit like ghosting to me. I don't know if that is useful to you but when I searched ghosting and vxgi I found this page about another ray tracing method https://bc3.moe/vctgi/ where they use TAA to reduce ghosting in post-processing.

You've already improved the game so much so thank you for all the hard work that you put into this.

[f4ijunkie]

I look forward to this new release! Hope everything is well with you and thanks for ALL the work you have done over the years on this massive community project.

Can't wait to really push the limits with the latest Hook!