Still on the fence whether I should downgrade my 8k X pledge to the normal 8k or not. Would like to be prepared for native 2x4k but also would like to use it earlier with GPUs that are available now/Q2 2018.
Currently it’s yet unknown whether the 8k X will support hardware upscaling or not.
Now I saw that the supersampling settings in SteamVR seem to work in both directions - you can also subsample with factors < 1.
So some questions to the VR experts in this forum:
a) would you expect a visual difference between subsampling in SteamVR with a factor of 2560x1440/(3840x2160)=0.44 and hardware upsampling from 2560x1440?
b) Presuming we have the bandwidth to transfer 2x4k via two DP cables: How much more stress on the CPU/GPU would it be to render in 2x1440p, upscale 2x1440p to 2x4k and transfer 2x4k compared to just transfering 2x1440p and leaving the upscaling to the HMD?
If the answer to a would be “no visual difference” and the answer to b “no big additional hit on CPU/GPU” then probably it wouldn’t matter so much whether hardware upscaling is supported or not(?)
I’m not sure, but i’ve heard you can refuse from X even after kickstarter campaign end and you will get the difference back.
Might need a confirmation.
In addition: if you pledged for X you will receive non X as soon as possible, just let them know you want it with the survey after campaign end (its 100% confirmed).
Thanks, having the option to get the 8k first is nice. Would be even better if we wouldn’t have to decide immediately when the 8k X becomes available but to have this upgrade as an option we can decide to go for when we think “the time is right” - two GPU generations later or so.
For a), there will be slightly less aliasing (the lens compensation will be a little more accurate) with an equivalent subsampling compared to panel level upscaling, but the difference is probably not very notable.
b) is a little harder to parse. If we’re talking about using the same size renderbuffer and different sized framebuffers, the larger framebuffer will require more GPU memory bus capacity, typically less than a percent. For reference: a 1080Ti has about 484GB/s transfer rate, and assuming 32 bits per pixel, the full 8K X transfer rate is about 1.5GB/s. A 1070 has 256GB/s. The GPU will run a bit more than twice as much sampling for the lens compensation pass, but it’s again a tiny portion of the workload. There is caching in the GPU that makes the access pattern difference in scaled vs non-scaled readout insignificant.
Thanks! That sounds promising. Would speak for keeping the 8k X no matter what…
Edit of edit: Transfer rate shouldn’t be a problem, right? 384021602 Pixels * 90 Hz * 4 Bytes < 6 GB/s. So not a real challenge even for 1070 memory bandwidth wise(?) (Sorry, misread the sentence about transfer rate - you essentially already told above that it’s no problem in that regard. So back to the initial conclusion: keeping the 8k X no matter what )
This was there from the beginning of the Kickstarter, right? In the responses to backers they still wrote some “maybes” though.
But I am mentally preparing for the case that hardware upscaling won’t work (or at least not be confirmed before the end of the Kickstarter) and the question whether I should still keep the 8k X. From the infos I read now regarding subsampling I think it’s still a save bet. Wondering why Pimax isn’t emphasizing this if you can get pretty similar results with 8k X and e.g. a GTX 1080 TI when using subsampling and 8k with internal upscaling.
Perhaps because at least in my SteamVR settings the smallest subsampling factor is 0.6 - which is higher than the 0.44 you would get from 2560x1440. So the lowest possible setting would still be a little bit more demanding (x1.36), so a GTX 1070 might not make it anymore. Will have to investigate, but I wouldn’t wonder when you could overwrite the subsampling factor with even lower values though (registry etc.).
Not sure why Pimax is so inclined on keeping the number of 8k X low. Perhaps they don’t want to advertize the subsampling option because of the support effort (people complaining because they didn’t enable subsampling and then complain because it stutters like crazy)? Or there are other problems I don’t have on the radar yet?
people like youshould just go with 8K instead of 8K x
If you pledge for 8k X you should know exactly whyyou pledge for 8k X…
There is 1 difference and thats native resolution, and if you dont understand why this require more power, then go for 8k with upscaling. serious do people read or comprehend what PIMAX writes when selling items?
Pledging for 8k x and demanding that PIMAX team also put in something so you can use it almost like 8K is fck stupid.
Thats like asking for a ferrari to be also able to drive 10mph/h while a ferrari isnt designed to drive so slow , if you want to drive that slow there are 5000 other models of cars outside you can pick…on the other hand you can’t drive a mini cooper 300mph/hours for example, thats why you buy high end cars…
Not hard to comprehend is it?
Just don’t fuck it up for our 8k X pledgers with you downgrade questions
Thank you very much.
I have no hard feelings, but plz if you make a decision…think before why you make that decision.
SO annoying , instead you should demand its 4k native instead of being worried you should be able to go below 4k native makes more sense if youpledgefor the X version imho.
Or there are other problems I don’t have on the radar yet?
You can read requires 1080gtx ti or even SLI or next generation cards?
Im an owner of 1070gtx but i know if i pledge f or X version…i need the next generation card at best…
I think for you its just best to go with 8k instead of X , you not very sure and you want this and that and this and that.
PLedgers for 8k x only want 4k native, no upscaling BS, and we are prepared to invest in great expensive +700$ cards if needed.
Please calm down, nobody is trying to take anything away from you. Native resolution would of course still work.
But if neither subsampling nor upscaling would be possible then I’m conviced no 8k X backer could properly use it even in 2018 (unless Volta will bring a > x2-3 acceleration which it most likely won’t (*)). And 2019 Pimax will compete with another generation of VR displays. So imho subsampling or upscaling is the only way to make 8k X viable - the main difference to the normal 8k being that you can set it to the optimal resolution-to-smoothness factor your GPU can still handle (e.g. higher for video etc.), not already peaking at 2x1440p.
(*) and SLI VR has to explicitly be supported by the applications. Up to now it isn’t (for more than 1-2 demos) and I don’t see this becoming a priority for game developers in 2018 with 400 Pimax 8k X out there…
I got a confirmation by email from support that the 8k X will NOT support upscaling. I had asked whether to downgrade to 8k or not. I did downgrade my pledge after receiving that email. It might be possible to upgrade at a later date. there was some discussion about that previously in the forum.
As an aside, there will be a AMA in the Reddit forum by pimax on monday at 6pm eastern time. I hope most of these questions will be addressed then.
NoamLoop if your statement is true that being " But if neither subsampling nor upscaling would be possible then I’m conviced No 8k X backer could properly use it even in 2018." I personally believe that if Pimax doesn’t let us know by the end of the kickstarter campaign, there is going to be 400 very disappointed and upset investers. Can you imagine getting such an expensive device and it not working for a period of 6 months or longer? I hope they could guarantee us that it will work, obviously most of us will take the gamble if, not knowing how well it will work is the case vs not knowing will the 8kx work at all.
@Fresco - yes, that’s why I was/am also unsure what to do. But if we can use GPU-side subsampling (so the GPU only renders the image with e.g. 2x2560x1440 and then upscales it to 2x4k before sending it to the HMD - so it just has to be able to show 4k images) then I assume even current high end GPUs should be usable. (Hearing some statement from Pimax would of course be helpful. But my guess is they won’t say anything until they have tried it. And as it looks getting a 8k X prototype done before the end of the Kickstarter does not seem to be a priority for them.)
My hope (and the main reason why I still consider to stay at my 8k X pledge) is that we can use better-than-2x1440p to watch movies with the cards that will be available in Q2 2018 (4k@180 Hz is still scary - but projecting a hardware decoded movie to a surface might still be in the cards - perhaps even with today’s 1080 TIs).
With the option to get the 8k first and additionally being allowed to exchange the money difference for modules or even get back the money when we should decide against getting the 8k X later the uncertainty factor on our side is mostly whether we trust Pimax to really allow all these fallback-options later on. Currently I tend towards taking that gamble.
Here some interesting (and imho funny) video where a guy is trying out supersampling settings with a 1080 TI:
For obvious reasons he is not cranking it up to the levels where it would become comparable to the situation we would be in with Pimax 8k X at native resolution.
The supersampling setting in SteamVR already contains a default safety margin for lens correction etc, so a setting of x1.0 is really already x1.96 compared to native resolution. (The default “x1.0” framebuffer resolutions in SteamVR is 1512x1680 per eye, the native resolution is 1080x1200 per eye for Vive))
So to simulate 4k framebuffers @90 Hz per eye (thus without any lens correction safety margin) you would have to choose a factor x3.2 in SteamVR when having a Vive connected (or x6.4 if we would add the same lens-correction supersampling safety margin for Pimax 8k like it is currently used for Vive at “x1.0” setting…)
If somebody has a 1080 TI and a Vive - could you please try to set it to supersampling setting x3.2 (and if time permits also x6.4) and do some fps measurements with first the simplest game/movie playback software you can find and then e.g. with Elite Dangerous? For science
P.S.: The resolution calculation chart in the video does not match to what SteamVR calls supersampling factor in the settings/developer dialog. The factor in this setting is increasing the overall number of pixels of the image accordingly. The 1.0 setting shown in the video is still right with 1512x1680, but x2 is not 3024x3360 per eye but 2138x2376 - twice as many pixels, not twice as high horizontal and vertical resolution.
Not 100% sure whether the results he shows are based on his understanding of the factor or whether he just dialed in the factors in SteamVR and thought it would have been the resolutions he wrote in the video. Looking at the frametimes he got imo it looks like the latter is the case (if not then the 1080 TI would be a beast )
Thank you for your reply and its nice knowing someone else has the same concern as a backer for the 8kX model. It seems Pimax is still not certain what they are going to do with the X model. Maybe someone like @Heliosurge or @LoneTech could get in touch with the developers to find out at least what is probable. I have heard two different things now on the Pimax 8kx. and as an early bird backer I really do not want to give up my spot to just except the regular 8k. I don’t want to brag by listing all the specs but I have a very high end all liquid cooled PC with two high end graphics cards and yet that may not even be sufficient to run the X version as far as anyone knows without concrete information from the Pimax developers.
I just noticed you uploaded a video, I’ll have to check it out.
Just checked out the You tube video link you provided, thanks. Joshdub has interesting sense of humor I’m suprised I had not viewed any of his material before funny but serious at the same time (well as serious as graphics cards can be and the subject of VR for entertainment purposes). I noticed also he has a large number of subscribers to his channel. The supersampling he described is in my opinion very appropriate for discussion on this forum as its related to VR and Pimax.
Not really bragging imho. Folks posting their specs is quite usefull.
Others with similar setups can help one another
Saves us asking for specs to debug problems.
Some forums users have their setup(s) as a tagline.
Now the idea sounds good to me and i think should be workable but with the liklihood of a performance hit when compared to base 8k.
I would think maybe after the game is finished rendering the PiMax driver can likely request the gpu to upscale image either before VR rendering or after.
A good prestesting might be to see about trying this on the 5k model as i believe it has no scaler like the 8k-X. And might be an idea to possibly add a lower spec gpu option(maybe). Perhaps a 1080p/eye that is upscaled by the gpu to 1440p/eye. It will also i beleive increase load/stress/pressure on Gpu.
On VRMark with Advanced mode I can do runs at 5120x2880 which is 14.75M Pixels vs the resolution the pimax will be running is 7680x2160 which is 16.56M Pixels, so about 10% more.
This is on my 1800x @ 3.95 (4.0 gets the odd crash no matter what I do when I try to do encoding etc ;x) and 1080ti OC’d to 2000mhz & 6050 memory clock (it can’t hold 2000mhz in the testing though
For whatever reason the results for below ones wouldn’t upload, and I can’t link images as a new user, can link one however! so the blue room results below
5120x2880 Blue room (Very graphically intensive scene) 89FPS Average Orange room (Less Graphically intense) 133FPS Average
and for contrast scores at Vive Settings
Vive 3024x1680 Blue Room 152 FPS Orange Room 204 FPS
Now looking at these in contrast, the vive has only 5M effective pixels showing on screen, obviously there may be some CPU bottlenecks present and for this reason I’ll be primarily looking at the Blue Room Results.
Roughly speaking the Above test has 3x the effective number of Pixels then the Vive, the 5120x2880 vs the 3024x1680, more percisely 2.9x the # of raw Pixels.
Now you’d expect then 3x less performance, but that obviously isn’t the case. In this test we saw only a drop of about 41% in performance, which clearly means you cannot calculate VR performance by raw Pixel density, else we’d expect to see fps closer to around 40.
I’m completely fine with this. Ordered X version as i want a “High tech” headset, i want to see on my own if it really looks better than upscaled and if the next generation of nvidia cards (which i was waiting since maxwell 970gtx) is capable to handle that. In addition to this i’m a little bit sceptical about all this, but it doesn’t make me stop wanting it
p.s. i dont feel sick from fps drops and reprojection in work. I dont have big hopes on X, mentally i’m with pimax 8k regardless the version, but still with a limited edition, call me a tester if necessary It’s not like they really trying to sell it, rather our own request to them (in fact there was no X version until pimax customers demanded it).
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