Question about choosing VR equipment along with hardware required for fidelity and performance

Development Platform & Builds XR Development
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Hello everyone, it was just recently that I started with UE - after a long break from 3d in general, and I have to say I am impressed with what I’ve seen so far. I am thinking of switching a career and I have in mind working with Arcvhiz VR in UE. I apologize for the long post, so hopefully you guys read it :slight_smile:

I have no VR experience - except trying PSVR once, which got me a bit dizzy - but I think it was due to wearing it incorrectly. Unfortunately, where I live, I don’t have any stores around me that showcase VR, nor do I know anyone that has one.

I know the theory - the resolution, the Hz, the screen door effect, the motion sickness effect - however, I am not really sure which one is the most important - I can only assume it all starts from high Hz, but then, what kind of system is required for it to run properly with all the bells and whistles? Obviously, when you are talking about archviz, you expect high polygons and high level of reflections, lighting, so we are talking ray tracing - I read that Lumen is not possible on VR. I also realize the cable problems, the screen door effects, etc

So, here are the questions I have:

  • Which is considered the best VR at the moment and why? People that have experience with more than one VR device, please share the pros and cons and which one you ended up using! Mentions to specific devices to avoid and why are more than welcome.
  • Are Hz the most important factor to avoid motion sickness? Is it performance? How you wear the device? Can a VR helmet be comfortable enough so that it doesn’t cause motion sickness at all? Assuming I end up doing VR archviz, obviously I want the VR to showcase the work, not for personal use, so how can you make a random person feel comfortable?
  • What resolution is considered good enough to have clear visuals? For comparison, I don’t mind watching 1440p vs 4k on my tv given the perfomance gain.
  • I saw Occulus Quest is wireless, but from what I’ve read I am not impressed. Are there any other wireless headsets?
  • Is it a good time to buy VR right now? I can hold on a while longer, saw new HTC VR coming in the market, but am not conviced it’s the right choice.
  • LCDs black equal to gray, but OLEDs have the screen door effect more accented. Which one is considered better?
  • Assuming you get a great VR device, what kind of system is required to run it? Judging by the numbers alone, if you have for example a VR like Vive Pro - 1440x1600 per eye, total pixel count is almost half of 4k - will UE be able to handle this resolution at 90Hz using ray tracing? For example, my current PC is i5 9600k, w/3060 Ti. My current test scenes, fully unoptimized run acceptably at a resolution I like @60Hz. But 90Hz?
  • Last but not least, I am not willing to spend a whole lot on a high-end laptop with 30XX RTX just to take to the clients. Can you use VR in windows without a monitor, eg, boot, browse the web etc as a monitor replacement? I find it a better idea to have a small-factor best desktop that you can carry for presentations if the VR allows you to work without a monitor.

Also, I realize that it is a strange period to enter UE - I think UE5 and lumen is the future, but it’s still very buggy. I tested 4.26 and 4.27 and I find it a mistake to spend time learning soon-to-be-legacy-software, but from what I’ve read UE5 is still very buggy regarding VR - but again I don’t mind waiting it out for some time until I feel confident with everything else.

Thank you everyone that read all of it, and looking forward to your replies!

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Hi scooterlord1, I work in the engineering/design sector and my role is visualization in VR. I’ll do my best to be as detailed as I can :slight_smile:

  • Which is considered the best VR at the moment at why?

It’s accepted that from a technical and experiential perspective, Valve’s Index HMD is the best one available right now. In my professional opinion, however, it has some drawbacks, most notably that it still uses outside-in tracking which means it needs base stations to work, which, in turn, means it takes at least 3 power sockets to work properly. Not fun dicking around with powerboards and base stations when a client is tapping their foot impatiently.

Oculus’ Quest 2 is definitely the best value HMD on the market, both in dollar cost and general usability. With a Quest 2, you can ‘airlink’ to your PC, which means you can have PC-powered VR without a cable, which is nice. You’ll also be free to develop for Quest standalone, which will be an advantage in the future.

Im personally not a fan of the Vives, but they are getting better, I hear. The unusable baseball-bat controllers and outside-in tracking combined with a heavy headset and fairly average screens all pulled down my opinion of the first Vive. They’re also abusively expensive for what they are, so tread lightly.

My personal favorite is HP’s Reverb G2. With 90Hz refresh rate and enormous screens, the visual fidelity is second-to-none, plus it’s got inside-out tracking which is a bonus. Im certain someone will chime in and say that the Reverb’s tracking isnt good, but I’ve owned one since it was released and havent had a problem with the tracking at all. It’s demanding, though. At full resolution you might struggle to meet the magical 90fps required to do it justice, but if you use it with SteamVR you can set the resolution on a per-game basis and to give you an idea of just how big the screens are, setting an app to 50% resolution in SteamVR still produces a higher resolution image than in a Rift S.

  • Are Hz the most important factor to avoid motion sickness? Is it performance? How you wear the device?

In order to achieve the smoothest possible experience, your in-game frame rate needs to meet or exceed the refresh rate of the HMD, so for G2 that means your target is 90fps, and for Quest 2 your target is 75fps (or 90 if you enable the option in the Oculus app). As for fit, as long as its firm on the head without creating pressure (pressure on the head will cause headaches) then its fine. You need to be mindful of interpupillary distance (matching the distance between lenses to the distance between your pupils) in order to match the images being presented to the eyes to achieve a ‘true’ 3D effect and to minimize chromatic aberration (red and blue edges on the left and right sides of objects).

  • What resolution is considered good enough to have clear visuals?

There are console commands in UE4 that you can tweak to explore this, named r.ScreenPercentage and vr.PixelDensity. Lowering these from their default 100 and 1.0 respectively will lower visual fidelity but increase performance. Quest 2 and Reverb G2 both effectively eliminate the screen door effect, which is caused by the actual physical screens in the headset anyway, so this depends on HMD.

  • Are there any other wireless headsets?

Ask again around Christmas.

  • Is it a good time to buy VR right now?

Yes, in my opinion. Id recommend a Quest 2 as a first buy, largely because its cheaper than its competitors, is great to use, and probably wont be superseded for another 6 months. If you want the finest VR experience possible, Reverb G2 and Index are both flagship models that will remain ‘current’ for at least the next year. There’s a few on the horizon (check out DecaGear) but until something hits the consumer market that’s a clear game changer (still lookin at you Deca) this is the situation.

  • LCDs black equal to gray, but OLEDs have the screen door effect more accented. Which one is considered better?

Quest 2 has really vibrant and bright screens and the blacks are really dark, and this is achieved with LCD screens. Honestly, in practice you probably wont notice a difference.

  • Assuming you get a great VR device, what kind of system is required to run it?

Well, you cant use ray-tracing in VR at all, sorry. There’s an old adage in VR development circles that states ‘code like its 1999’. Regardless of machine, the hardware requires frames to be rendered for each eye and (almost always) also on your PC screen, so your performance cost triples immediately, at least. To answer this question appropriately, it depends on the game; once you get your HMD, pick up Gorilla Tag on Steam and compare it to, for example, Half-Life:Alyx or Saints & Sinners.

To give you an impression of how demanding VR can be, my machine has a 6900XT, 32Gb of RAM, and a 3700X and I can grind that beast to a halt with some games.

  • I am not willing to spend a whole lot on a high-end laptop with 30XX RTX just to take to the clients. Can you use VR in windows without a monitor, eg, boot, browse the web etc as a monitor replacement?

Hmm I’ve never tried this, but my hunch is no. You need to have Windows running to have the VR frontend running, be it WMR, Oculus or SteamVR.

Take it from someone that develops in UE4 for VR on a daily basis, do not use 4.26. 4.27 should be the version that you commit to using right now, despite the bugs with OpenXR (and you should also commit to using OpenXR). If you want the most stable version to develop with, use 4.25 - though you will need to wrangle the SteamVR, WMR and Oculus plugins if you want to ensure compatibility with the big three frontends. In time, OpenXR will improve greatly and it will (ideally) work out of the box with any major platform.

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Hello Bevman and thank you for your wonderful response, you have cleared some things up for me, but now I have a new set of questions.

-Regarding tracking, are the lighthouses so much better? Is the benefit just ‘better’ tracking or does it have to do with the controllers as well?

  • Can you mix HMD and controllers from other devices plug-n-play?
  • …your in-game frame rate needs to meet or exceed the refresh rate of the HMD, so for G2 that means your target is 90fps, and for Quest 2 your target is 75fps (or 90 if you enable the option in the Oculus app)…

-What if you get 75Hz on both devices? What if on a 90Hz device you get 75Hz? IF 75Hz are good enough for one device, aren’t they good enough for the other device? Also, is there a way to somehow calculate how much fps you are going to get using UE in that kind of resolutions?

What resolution is considered good enough to have clear visuals?

  • Well, you cant use ray-tracing in VR at all, sorry. There’s an old adage in VR development circles that states ‘code like its 1999’.

The most worrying reply I could have read. No ray-tracing at all? Is it not possible, or is it considered too slow? Again, I am not interested in game development, nor do I care about other people’s hardware, as long as my own hardware is good enough to give impressive archviz results.

-So, lumen is not getting any support for VR - I read that explicitly from a UE dev, if ray tracing is not supported, how are you going to achieve ‘realistic’ results in VR? I guess the answer would be faking it, but, how can you fake reflections? I am not really sure how reflection cubes work, but, if you have an answer about this one, please share.

-Regarding using a VR without a monitor screen, I am not really sure what the ‘VR Frontend’ is since I don’t have a device yet, and obviously I don’t care about command-line stuff, just boot and enter UE. I guess I’ll find a solution, like using a device to remote control it, etc. If anyone else that reads this post has an answer, please share!

  • Take it from someone that develops in UE4 for VR on a daily basis, do not use 4.26. 4.27 should be the version that you commit to using right now, despite the bugs with OpenXR (and you should also commit to using OpenXR). If you want the most stable version to develop with, use 4.25 - though you will need to wrangle the SteamVR, WMR and Oculus plugins if you want to ensure compatibility with the big three frontends. In time, OpenXR will improve greatly and it will (ideally) work out of the box with any major platform.

This is the second most worrying part of your reply. It’s not that I have too much experience, but so far, I tested 4.26, 4.27 and 5. I can only assume you are suggesting 4.25 for commercial purposes. As I said I am only interested in designing for my system and showcasing in person. Excluding this, is there any other reason you are suggesting 4.25?

-4.26 didn’t support RTX GI volumes - this is why I installed 4.27.
-4.27 didn’t support twinmotion material library out of the box - this is not a huge problem per se, but still, you are missing a good base of things. Also lack of integrated quixel bridge, etc.
-Now 5 Early Access… I see the potential but I also see the bugs and the incompleteness. You can get around a few things, like lumen shortcomings and plan ahead for the future. Quixel mixer export to UE5 bridge not working. These are serious bugs, but I can bear with them and can do what I need so far.

-Last question - I see all these archviz VR demos on youtube… if ray tracing doesn’t in fact work, how can you achieve this kind of realism? Screen space reflections? Any tips/pointers are welcome.

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I don’t have any experience with archviz, but in general the key to getting good visuals in VR is to bake as much as possible. Most screen-space effects work extremely poorly in VR, and a deferred renderer does not scale well with the increased display resolution and stereo rendering. The best option is really to use the forward renderer and bake as much of the effects as possible.

If you take Half-Life: Alyx as an example of a game with very high visual fidelity, practically all lighting is baked. Every surface the player can get near has high resolution directional lightmaps. All shadows and ambient occlusion apart from dynamic moving objects are baked into the lightmaps. The reflections are very limited though, as they are done with single parallax corrected environment captures.

Over that, the UE4 forward renderer supports blending between 3 reflection captures, as well as planar reflections.

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Rectus hi,

thanks for your feedback. It is indeed valuable. This is the first time I heard about a ‘forward renderer’, I quickly googled it, looks like I have a lot of reading/testing ahead of me.

The whole thing is kind of a letdown, I would expect the VR tech to have matured more than its current state - I guess you can’t have everything right?

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No worries, happy to share whatever knowledge I can :slight_smile:

  • Can you mix HMD and controllers from other devices plug-n-play?

Nope. The only possible exception to this is WMR controllers. Otherwise, you cant use Rift controllers with an Index, for example. You also cant pair more than 2 controllers per headset.

  • What if you get 75Hz on both devices? What if on a 90Hz device you get 75Hz? IF 75Hz are good enough for one device, aren’t they good enough for the other device?

Aim for 90fps across the board. Chances are, anything above 75fps is going to look fine, but your target fps should be 90. In practice you may notice that lower framerates are acceptable, but this isn’t ideal. If your project can hit and maintain 90fps, you’re set. This connects to a broader discussion about performance and optimization, not to mention target hardware and requirements. One thing you can do if, say, your project is mostly hitting 90fps is perform an event tick calculation to find the frame rate and lower screenpercentage or pixeldensity when it dips under a threshold.

  • What resolution is considered good enough to have clear visuals?

This depends on the headset. Older headsets with lower resolutions are going to have lower visual fidelity than newer, higher-end headsets by comparison. At a screen percentage of 100 and pixel density, you’ll see as many unique pixels as the headset is capable of. If this causes problems for performance, one option is to lower these values at the cost of fidelity and find a compromise between performance and resolution thats acceptable. Its all a balancing act :slight_smile:

  • No ray-tracing at all?

No ray-tracing at all, sorry. This is just straight-up not possible at this time from a technical perspective and even if it was, the cost on the system will render your game unplayable even on the highest performing machines.

  • how are you going to achieve ‘realistic’ results in VR?

I’d recommend playing games like Half-Life:Alyx and Robo Recall for yourself. These games are about as good as ‘realistic’ visuals in VR gets. There’s a stickied thread in this forum that talks about maintaining frame rate in Robo Recall that includes info on complex models and high-end shading effects such as reflections. Reflection cubes/spheres work basically by drag-and-drop into the scene, and you can add them to your sky light to match ambient coloring.

  • VR Frontend

By this I mean the program that windows runs to pipe data to the HMD. For Oculus HMDs, this is the Oculus app. For WMR HMDs, this is the Mixed Reality Portal. For Vive and Index HMDs, this is SteamVR. You can also run SteamVR for Oculus and WMR HMDs, but not without having the Oculus app or the Mixed Reality Portal running at the same time. For Unreal development (particularly with OpenXR in 4.27) this doesnt really matter. You could, potentially, turn a machine on and launch your project without a screen, but youd still need at least a keyboard to log into windows. The VR frontends will open automatically when the headset detects activity (usually a light sensor inside the face gasket).

  • I can only assume you are suggesting 4.25 for commercial purposes

Correct. I wouldn’t even use 4.26 for hobby/side projects, since core functionality in the engine is straight-up broken for VR. Translucent materials, for example, fail to render in both eyes. I also had problems with certain dynamic elements not rendering properly. For utmost stability, stick with 4.25. 4.27, however, should be where your focus lies since the introduction of OpenXR and everything fubar’d in 4.26 is fixed.

  • I see all these archviz VR demos on youtube… if ray tracing doesn’t in fact work, how can you achieve this kind of realism? Screen space reflections? Any tips/pointers are welcome.

They’re either using beast-tier machines for real-time lighting, a custom, source-code version of the engine to force certain functionality on in VR, or (much more likely) they’ve very carefully wrangled lighting builds for the highest possible quality static lights. Rectus_SA has expanded on this in a previous comment. Like I mentioned, its all a balancing act. If your game is performant in some areas, you may have the headroom to enable certain real-time effects.

I made a few comments in a thread some weeks ago that goes into a lot more detail about things you can do in the engine to juice performance: What are the Performance-killer for VR(eg.OculusQuest2)? all postprocess, all screen-space? - #2 by Bevman00

I hope that helps! :slight_smile:

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