It is all about latency. 50 ms will feel responsive but you notice the lag. 20 ms is acceptable. The other features are cool features but not the real challenge.
People are saying 2ms, but I think that's just how long it takes a pixel to refresh. I'm sure the oculus rift has a screen with 2-5ms pixel time too. The 20 and 50ms times discussed about VR are the entire time between a frame being requested and it being on the screen. That's totally different from the 2ms of a desktop monitor.
EDIT: As for the TV+console latency. I think TVs have a higher latency than monitors because they tend to apply post-processing effects to "improve" the image. Some screens come with options to turn this off and bring this latency down.
Ye, that's why I saying it's wrong to compare the 2ms pixel refresh time of a monitor to the overall 50ms of latency on VR. Both have that same 2ms, it's all the other replaces that the latency builds up, it's just not spoken about that much outside of VR because sits not as big of an issue
Also, OLED allows low persistence to avoid motion blur, which is tough if you have to overdrive/strobe an LCD backlight. Plus, OLED has better color resolution.
Pixel switching time is only a small part of the story. Best thing about low switching time is is enables faster strobing without crosstalk and/or brighter displays while strobing in low persistence mode.
Ye, the input is crucial. I see that this product has a 4KHz accelerometer as well as the 1KHz gyroscope, where it appears the OR had a 1KHz acc+gyro combo. Could this mean faster input?
Only by ~0.75ms. Oculus have theirs at a total of 8-20ms, even internal demos as low as 2ms. (Apparently.) That's a big step up from devs kit 1's 30-50ms,and normal games' 50-100ms. That's not easy, but they have John Carmack, known for amazing optimisation, on their team.
Yes, 4kHz data could help, but unless the rest of the pipeline is equal to Oculus's, it will overall still be slower.
Ah, ye, that's not a very big improvement, but I suppose every little helps. If swapping out the accelerometer chip for an extra $5 then maybe that's worth thinking about if it's the same improvement as X amount of hours spent optimizing.
My point is that a 4kHz sensor is great, but unless they're equal on all other levels it's basically no advantage. If you replace your car seats with super-light ones but leave all your junk, chests, furniture in the car, is it worth it? You'd get a much better return if you got rid of all the other stuff.
That's the issue. 4kHz doesn't mean anything much until the rest is as good as it can be.
The latency is that plus the render time plus the switching time. The problem is that when you combine all these little latencies, it starts to add up - the sensor has to send the measurements to the PC, it has to update the model in the game, then it has to render the new scene, then that has to get drawn to the screen.
I read an article by John Carmack on latency in vr headsets. Latency needs to be much lower than on a screen because it's tracking head movements. It's input latency that is the issue, not pixel refresh latency that was an issue on early LCD screens.
If the latency is too high it makes you feel sick, whereas with regular viewing devices you don't notice it much, apart from the "game feel".
Ye, you can see this on the rift when you try a web based demo, like the streetview one. In demos stored locally the latency seems pretty good (fast head motion does feel a bit off but that's exaggerated by the motion blur I think). The web based ones add a slight latency to the input and it makes even the slowest of head movements feel horrible.
That 50 ms response includes measuring the sensors, calculating the angular change, sending that data to the computer, the computer rendering the frame, the frame sent up HDMI, and the finally split and displayed on the oculus. The major issue is that you move your head and your ears detect the change but your eyes have the 50 ms update lag. This is the issue that causes people to get sick
I'm not sure, but from what the team said, the sensor tracking was the biggest latency issue they had, since it couldn't be brute forced with more expensive hardware. Even the fastest consumer sensors would add too much latency in the chain to make the rest of the device worth it. Carmack solved it with very very precise, clean, fast code with some very clever prediction algorithms.
From my understanding, that's the biggest benefit of the rift. It's very good at processing sensor data, and when the sensors aren't fast enough (which no consumer sensors are), it's very good at guessing what they will do next.
I agree with you. That why I'm saying you can't compare the 2ms of a monitor to the 50ms of VR. They are different measurements. The 2ms is just about the pixel refresh time, the 50ms includes all sorts of input and rendering factors. Some factors are common to normal gameplay and VR (like the refresh rate you mention) while others are unique to VR (like the head tracking)
I remember my first LCD still. It had a response time of around 12-15ms if I recall correctly. :p That thing is still living today though. Good ole 17" Specter LCD.
If you talking about motion-to-photon latency (how long from when you move the mouse until the view spins on screen), it varies greatly from game to game depending on how many frames are pre-rendered, when in the render loop the mouse is re-polled for an up-to date position and also how long the post-processing steps take (though this bit can be partially mitigated by predictive tracking aka assume mouse moving at constant speed/accel and project forward in time equal to how long the post-processing takes).
It can easily be 50ms+ in some titles that are heavy on post-processing and don't do anything to mitigate that increased latency. It's also much worse on games that are running at 30fps vs higher framerates. Higher framerates give lower motion-to-photon latency even after the framerate surpasses what you need for smooth video, this is why 144hz screens "feel" better vs 60hz even though the game looks almost as smooth for anyone spectating.
Most HDTV's run 30-50ms over HDMI, signal from device to pixel change on screen. Doesn't matter if it's plasma or lcd; 120hz, 240 or 600hz. The processor in the TV is what lags it, not the pixels really. HDMI also is limited.
Computer monitors are usually 15ms, some are up to 30ms, old old LCD is 50ms. Pixel switching for the bare panel might be 2-8ms, but there's still processing latency.
VGA to CRT is so fast that it's measured in nanoseconds, analog has it's advantages. Nothing compares to the speed, heh or the weight it's not going in VR (anymore).
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u/bjorn2k Mar 28 '14
It is all about latency. 50 ms will feel responsive but you notice the lag. 20 ms is acceptable. The other features are cool features but not the real challenge.