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NVIDIA VXGI Integration

Hi all,

Link to the latest version of the VXGI integration (4.12.5): https://github.com/NvPhysX/UnrealEngine/tree/VXGI-4.12

Since it has been mentioned numerous times now, and again just recently in the NVIDIA GameWorks Integration thread. I thought it was high time a new thread was created for each of the GameWorks integrations - 84 pages is a lot of information to go through just to look for specific details on a specific integration. I will start with VXGI as it is the most active in development and feature requests and bug reports.

   @Alexey.Panteleev if you could post any updates/responses on this thread it would be very helpful.

If someone would be kind enough to PM me with a list of common questions/answers, I’ll add a FAQ to this post, as well as a guide on how to setup VXGI for use ingame and possibly also Archviz. I know quite a few people have posted these settings before, it would be helpful to have them in one location that can be referred back to.

Frequently Asked Questions

Q/ When I click on the above link, I get a 404 error from Github, what’s happening?
A/ The github repository is a private repository, you must be logged into Github and your Github account must be linked to your UE4 account. Please refer to the following link on how to link your Github account to your UE4 account: https://www.unrealengine.com/ue4-on-github

Q/ Do I need a NVIDIA 900 series or greater card to use VXGI?
A/ No, VXGI works on all DX11 enabled cards including AMD. The 900 series and later cards provide hardware features that allow you to get more performance out of VXGI. (Needs verification).

Q/ VXGI is too performance heavy is there anything that can be done to improve this?
A/ I have quoted @Chariots post on VXGI settings and performance below:
[SPOILER]

[/SPOILER]

Tried to access the GitHub link above and got the 404 message. Any idea what’s happening?

You need to be logged in to Github … I am going to assume it is a private repository. I was able to see the repository by logging in.

Thats a good first question for the FAQ, as that gets mentioned alot

Thanks!
I’ll post the updates in this thread from now on.

Will be launching up vxgi again today for the first time in many months.

First off, thanks for listing all this in one place. It should probably be a part of the FAQ in a dropdown for new users just picking up VXGI. There’s always a lot of misinformation regarding the performance of VXGI simply because of how obscure the performance settings can be.

As for that one setting in particular, it’s mostly just to save some extra VRAM. You can read more about it (and its surprising performance benefits) at https://forums.unrealengine.com/showthread.php?53735-NVIDIA-GameWorks-Integration&p=375783&viewfull=1#post375783

Setting it to anything below 2 with high distance (500+) can cause severe artifacts. On elemental demo map in throne room, indirect lighting can simply vanish depending on camera angle if this is set to 1.

hi, is it possible to test the VXGI in Unreal Engine without participating in the Nvidia Developer Program?

Yes, you just have to download specific build from github, compile and run some project or create one from scratch.

@Alexey.Panteleev Is there any chance we’ll see the issue I brought up with shadow cascades vanishing resolved with the 4.13 version of the branch? (Since it seems like shadows will need some attention with the cached shadow maps anyway)

As discussed on that other thread, this issue is gone in GalaxyMan’s 4.13 branch because Epic changed the cascade handling code. It’ll be a base for the official 4.13 branch.

I’m pretty sure they removed MapSize 32 a few updates ago, but you may want to double check that. Personally, I’ve found that lowering to 32 has almost no effect on performance, but a massive impact on quality. Also for those of you that like to preview single assets in-engine, MapSize 256 is INCREDIBLY useful for this, especially on skeletal meshes. Setting your stacksize to 1 gives little to no artifacts under a range of about 600, and makes MapSize 256 perfectly viable. Doing this essentially allows you to get Lightmass-like quality on assets that can’t be baked, and with full specular data to boot.

Whoa, when did they say that? I mean it can have a decent impact on mid-range hardware, but personally going from 2 to 3 only ever gave me a boost of maybe one millisecond, and I never noticed any improvements over 3. I feel like this is something that may have been relevant in 4.6 and was slowly improved over time. It just doesn’t have a good quality-performance ratio.

Other than that, nice rundown. It seems that half the stuff here is from when I broke Unreal as a hobby for months on end… not sure how I feel about that lol :p.

Speaking of breaking Unreal, I recently got a 4k monitor and can confirm that if there is anything that VXGI scales poorly with, it’s resolution. I’ve never seen anything so dependent on resolution for performance. I still want to try to speed it up some and play with it more (as I always do, thanks Nvidia!), but so far I wouldn’t recommend going much over 1440p with VXGI.

Mapsize 32 works still, at least on my machine. 256 crashes the engine outright, and my poor 3gb GTX 780 hardly avoids bursting into flames when I even attempt that.

They recommended tracing sparsity of 4 in their slides. Even 1ms of performance is very significant when you’re targeting 16ms for standard gameplay as opposed to still scenes. I’m surprised it doesn’t have more of an impact on your higher resolution monitor, I would think that would be the setting to affect it the most like that.

Ok, thanks for the info. Generally I only run the Unreal editor at 1080p or 1440p. At 4K, tracing sparcity does have a decent impact, but not enough to make the game playable. 4K VXGI is just a no-go all around. A lot of games I’ve played this year struggle at 4K without having real-time GI, so I’m not really worried about pushing it in that respect. I mainly use the 4k for stills, or for when I’m using baked lighting.

hey guys ,

just wondering what’s the best option between VXGI and static lighting to get the best Quality rendering scene

i am mainly trying to use UE4 to produce cinematics for archviz , so performance is not important in my case .

Static lighting. In case the scene is supposed to be dynamic you are forced to use VXGI of course which at max settings is too laggy…

Here’s the general rule - If you -can- use static lighting, you -should- use static lighting. Things like VXGI are primarily for projects that wouldn’t work properly without dynamic lighting, or just for previewing what static lighting will look like after you bake it.

It seems like the link for the GameWorks builds, dosent work. Any chance for a re-upload?

First question in the FAQ in the OP. Make sure your logged into your Github account and its linked to your Epic account, refer to instructions to do it.