SimRacing VR tips

All the new Oculus and Vive owners users coming this last year have been, somehow, a useful poll to understand and optimize resources in the quest for the final VR configuration file. Everybody seems to test and look for the 90 FPS steady-fancy experience and more searchers, the more chances to find the treasure. Here we have some interesting tips to play with Nvidia cards and Oculus Rift or Vive headsets.

Original source written by Sean A Fleming. If you read whole thread, more tips and other test have been carried along the pages.

This post started out as a general help thread for VR users in iRacing.
Over the last few days I’ve been able to uncover some seriously important info that will change both how you approach your VR setup as well as getting the most from your rig.
I have to thank the tech staff from iRacing for coming to the table and answering questions I had about what types of AA were actually supported by the current iRacing system.
The answer to this was an easy one – iRacing ONLY supports MSAA (very old AA that does produce good results but at very high resource cost) and FXAA (far less resource intensive than MSAA, but IMO makes the overall image appear blurry compared to switching it off. You can test this by turning it on, leaving the lobby and coming back in where you can then turn on and off and view the results).

I’ll leave all the other tips as they are still relevant, but let’s get to the main news – it’s going to be quite the eye opener for most!

True SSAA (aka SuperSampling/Pixel Density SS) is NOT SUPPORTED IN iRACING.
You read that correctly. Using things like the Oculus Tray Tool (OTT) or SteamVR to increase SS in the true sense of what SS means is not supported by iRacing at this time. This is not my opinion, this has been confirmed 100% by iRacing staff Dave Gosselin:

“We do not currently support true Super Sample Anti-Aliasing which renders the scene at # more samples per-pixel and then down samples to the final image.”

In more detail, what is “True SS”? It’s adding Supersampling to the image pushed to the HMD on a sliding scale (that scale most of you have been pushing to 1.2-1.8 or higher). That is, rendering the image at a higher resolution than the HMD’s native rez before finally downsampling and displayed in the VR headset.
Especially if you use the OTT or SteamVR to do this, you are 100% a victim of pure placebo effect and you are utilizing seriously resource heavy system power for absolutely no return. If you think that all the videos on Youtube, or even your own experiments have made the image better, sorry it’s placebo. I’ve been victim to this myself, the power of placebo is quite amazing.

But what about the “Pixel Density” setting in the dx11renderer.ini file that many manipulate, thinking that it’s SSAA or SuperSampling in the way that most of us understand it?
Here’s what iRacing tech staff had to say about SS in iRacing – this was actually a correction by iRacing’s Shawn Nash from a previous comment by iRacing’s Dave Gosselin:

“Dave’s comment regarding the rounding of the off-screen render target to a power of 2 was incorrect, it actually just rounds to a multiple of 4 pixels – so the final size stays very close to the value returned from Oculus SDK, within a few pixels. And as Dave was mentioning, increasing the off-screen size helps a little but gets very expensive quickly and will impact the frame rate and can cause stuttering. I prefer to use anti-aliasing for the Rift primarily (and even keep that pretty low to help the frame rate), and only increase the off-screen render target size using the pixelsPerDisplayPixel setting as little as possible – I usually just use a value of 120 – which improves the resolution at the sides of the view some without getting crazy expensive.”

The default value (in the DX11renderer.ini) is 116, you can raise it to 120 if you don’t see any negative impacts. I’m leaving it 116 on my rig (details in my signature).
Note – this value should be changed to 100 – thanks to a fellow VR racer for taking the time to not only show that increasing this beyond 100 is both resource wasteful and detrimental to the image – I think the post is close to the end of this thread at the current date of December 25th 2017

So what does that mean? Well, you can pump those wasted resources into other areas of the SIM, areas where you will actually be getting results for your horsepower investment instead of pure and utter placebo.

I was fortunate enough to chat with a tier-2 tech at Nvidia yesterday evening and just by chance he is an iRacing member.
He gave me some very basic settings that should be considered a baseline for most people running modern PC’s with at least GTX980ti levels of power. Beyond these settings, in-game options may have to be experimented with to get the best out of your rig.
These settings are all accessed in the Nvidia Control Panel (sorry I have no idea where they are in AMD cards but there should be similar options in the control panel). It’s best to create an iRacing profile here (running on the iracingsim64dx11.exe program executable) and then apply the following settings:

• Power management model – prefer maximum performance
• Threaded optimization – off
• Triple buffering – off
• Vertical sync – off
• Virtual Reality pre rendered frames – 3 (Yes, really! This has the impact of much faster rendering and smoothing of the image) – I’ve experimented with using a value of 2 and since it’s really hard to tell the difference, you can run 2 if you are trying to stabilize frames.
But don’t go back to 1, this setting really does help and is worth the resource.

Apply the settings, close the NVIDIA control panel & refresh the desktop several times before opening a new browser and launching iRacing.

As for in-game graphical settings, I’m using the settings in the attached images NOTE: I have changed the “Car Detail” detting to ‘Low’ in both graphics and replay – it’s nigh impossible to tell the difference in reflection quality so why bother wasting GPU trying to render something that’s not really noticeable in current VR tech?.
iRacing has never looked better and I’m not anywhere close to my rig’s capibilities. Of course tracks like LeMans have some interesting optimization issues that can cause FPS drops, but that’s really the only exception. Everything else is solid 90FPS with 47 cars rendered and visible at once.

Why am I not using High settings for Car detail? I’ve explained that below and I’d rather have the overhead in available resources if they are needed than image improvements that are almost impossible to see! I might select the higher settings after a few more days testing when I’m certain they will not put my rig close to capacity.

Useful tips for any other VR users – I’ve spent hours tinkering with VR and felt that I should share.

The settings in both Graphics and Replay called “Car Detail” is 100% only for reflections. I’ve tested this extensively and am positive that this is all it does. It does not turn on/off any physical aspects/details of the cars. It’s just for how the world (Sun, trees, buildings, passing surrounding) reflects on the surfaces of the car.
Note that I have changed this value to “Low” in both graphics and “Replay” – I haven’t updated my screenshot yet. There’s just no good reason to waste resources on anything higher

For a high resolution monitor, high looks much better than low, but in VR the difference is so minimal that it’s simply not worth the hardware costs. Try it out for yourself by watching a replay in VR (the side of the car is the best place to see this). Pause the reply when you see the reflections of trees/buildings etc and ideally the sun on the paint of the car. Then open your graphics options and switch between high and low on the car detail. Notice how it just softens the reflections just that little bit? You won’t even notice this while racing. But you will notice the FPS boost you get back especially if you are running a setup that’s pushing it already to maintain a steady 90FPS with ASW switched off (as it should be for any SIM).

The other option that you absolutely don’t need unless you have zero issues with FPS is Dynamic OBJS. The description says this only uses 50MB of GPU memory, but I don’t believe that. Using the Oculus Tray Tool performance monitoring HUD, you can see a large performance hit on VR FPS headroom that’s far more than 50MB if my card has 8GB of DDR5 RAM (GTX1080FTW).

FXAA is not something that will improve your image quality, unless you like the entire scene being blurred due to the way this algorithm attempts to interpret the scene. At first it looks like it is better, it helps with some of the shimmering you can see sometimes on the edges of fences and track/rumble strip borders. But if you pause a replay and pay close attention to your scene, you will see that it degrades the sharpness of your image. Neat trick but not for VR.
Update – some on this thread have been playing with the values (in the ini file) for FXAA and have had results they are happy to live with. If you are having trouble maintaining FPS at 90, then worth a look. If not, stick with the in game AA (MSAA) for better performance.

The ‘Sharpening’ setting is IMO the single most noticeable option in all the settings for VR experience. I’ve asked what it is, and iRacing provided a helpful explanation:
“Sharpening – This is another post processing filter. Since SweetFX wasn’t working with DX11 we implemented their Luma Sharpen filter (also pretty much verbatim) which was available under the MIT licence.”.

You should only be using only one, not two, three or more different anti aliasing together.
You are wasting video card memory by having each frame sampled by your AA’s 3 times over when it offers no difference in quality by using multiple AA tech that in most cases aren’t compatible with each other anyway!
You should be using FXAA when your RIG can’t handle MSAA (the AA option in iRacing graphics)

Unchecking two pass trees is something that will help a lot if you are seeing dips in FPS. The visual difference is noticeable, but it’s not that much of a difference that it’s a deal breaker IMO as I’m usually not checking out foliage!
Since the revelation regarding SS in iRacing, I’m checking this because I have a ton of resources.

Pit Objects can be pretty brutal as there’s unfortunately no current option to select ONLY your pit as the one with the pretty settings. I used to keep this setting on low, but I’m using medium and may move to high, once again given the freed up resources I was wasting on SS.

But still, this is no doubt why most frame dips happen around the pit area. iRacing really needs to add the functionality to allow drivers to only select their pit for higher detail objects. If they can’t do this with the upcoming very fancy animated pit graphics, it’s not going to get used by the majority of users as the overhead would be monstrous to say the least!

Car draw detail – pop-in/out:
Cars popping in/out and/or changing level of rendered detail – fix this by changing your LODPct setting in the dx11renderer.ini from the stock 100 to 25. This info was provided by Mark Pickford and is something that has been bothering many recently.
I tested this new setting in VR using a Spa reply and was able to see cars in their entirety from turn one just past the pits, watching them go all the way up au rouge until they disappeared out of sight around the corner. No loss in car detail whatsoever.
This setting will likely need to be played with for less powerful systems, but I’m having no issues with the replay I just viewed which had 40+ cars all rendered in the scene. Brilliant! No more pop-in/out! Please note that contrary to other’s suggestions changing “car detail” to high has absolutely no impact on this issue – it only impacts the reflections on the car surfaces as I already detailed

Hope this is helpful and if at least one person has a better VR experience in iRacing then it’s been worthwhile!
I still believe that the VR implementation in iRacing is the best of all the racing titles I own. And considering they do this with an aging system architecure that can only utilize 2 CPU cores!

Cheers.