Hi, I was wondering if 90fps is a requirement in HTC Vive or not. Oculus seems that is going to reject projects for Oculus Store that do not hit that framerate, that honestly is a crazy number if you add there the huge resolution and the stereo.
So anybody with a Vive that can share an answer. Can you run HTC Vive at 75fps, and still have low persistence and a good and fluid image output? Or is the low persistence feature locked to 90fps?
Thanks
hi janherca,
from my time developing for the Vive I would strongly recommend not running the Vive under 90 fps, this will cause motion sickness and headaches, it just doesn’t feel very nice. If 90 fps seems too high I would look at optimizing your project to suit.
Hi Chillybody,
Thanks for replying. That is something very curious to me, because I own a DK2 and when I run experiences or games at 75fps I feel them totally right in terms of motion sickness or headaches, and I am an average person, quite sensitive when VR demos aren’t fully optimized. So I’m still wondering why this new number of 90fps. I have had the chance to try a Vive, the first HMD with that framerate I have tried, and the experiences that I tried seemed to me quite close in framerate feeling than the ones I can try in DK2. Not so much difference that the one you have, for example, when you come from high persistence to low persistence.
So if don’t mind I ask you more, have you tried personally both modes in HTC Vive with the same demo? So then can you confirm me that there is a way to have Vive running at both 75fps and 90fps and still have in both low persistence activated? And still having 75fps with low persistence activated you have headaches and issues related?
Excuse me to push more questions. Really appreciate if you can add more light on this.
I’m assuming that @janherca is talking about running it at 75hz refresh as well, not 90hz refresh with 75fps, which it seems you’re referring to.
I hope I understand your questions, I had a bug that locked the Vive at 60 fps and I found that the experience was very unsettling, the 60 fps was based on the refresh rate of the monitor not the HMD so it should be somehow possible to lock it but I think 90 fps with more optimized content would be better.
In reference to the DK2 I couldn’t agree more that the 75 fps seems pretty good however I’m gong to assume that timewarp and direct mode probably play a big part in creating a feeling of higher fidelity fps, if timewarp creates a dummy frame between each frame then we could be talking about a 150 fps feeling.
I’m not sure if the Vive drivers/sdk provides a frame projection solution yet and it looks to me that it is still using an extended monitor styled setup so that could explain many of the differences you were talking about.
Out of all the time I’ve spent developing for VR hitting the recommended framerate always seems important as many other factors rely on that refresh rate, like timewarp etc. Optimization, low draw calls, optimized texture sheets are just a few ways to get that desired framerate.
If you haven’t already there are presentations where Epic provide a number of their optimizations to get their VR scenes running smoothly, I use these and haven’t had too much trouble hitting the desired framerates:
Hope that helps
Yeah, Chillybody, I think you have understand well. Thanks for the long answer. Perhaps I haven’t been very clear on the question. I mean, in DK2 low persistence only switches on when the framerate is 75fps or so, because low persistence is locked to be available at 75Hz mode of the screen. I think the screen can also be setup to work at 60Hz.
So that was my question. If Vive has an option to lock the refresh rate to 75Hz and still have low persistence.
It is an idea that I am having. If we can downgrade Vive from 90Hz to 75, then we can go for 75fps, and it seems not much difference, but in VR reducing 15 frames each second is huge difference. So you have more pixels in Vive than in DK2, and a better lenses, which will improve a lot the current experience we have now with our developments, but maintaining the 75fps as targer framerate and the 75Hz as the refresh rate in the screen, which I think is enough for a good VR experience, will make our requirements as devs a lot much easier without going crazy with tweakings in the optimization part.
Regarding timewrap, didn’t know that Valve hasn’t something there. I was in the idea that they had a similar tech for filling frames when framerate goes a bit down. But I see timewrap more as a secondary help in the mission to achieve the framerate. It is not going to upgrade to 150fps magically.
Anyway, thanks for the help and ideas. I’ll find out everything on this when finally Vive is released and I can grab my hands on it. 
This is a last year 2014 post, Same problem here, dose anyone find a solution to change the fps in VIVE ?
I don’t have one so I can’t check, but is it treated as a monitor, or using a “direct mode” type setup like the DK2?
If it’s the former you could probably assign it a custom resolution with 75hz refresh rate in your GPU control panel. Otherwise, no idea.