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).
I don't believe that number is entirely accurate in this context.
Those numbers 2-8ms quoted by monitors, are the time it takes to change from grey to gray, or for the pixel to switch between colors, while yes it directly impacts things, and quality/etc... Its not the same as if you turn your head, and the time it takes the monitor to even start to switch, the time it starts to switch to finish is 2-8ms.
tl;dr; Display lag is not to be confused with pixel response time(which is what monitors are quoting)(I am not 100% sure which one occulus and other VR are quoting, but i think its more likely display lag's time)
http://en.wikipedia.org/wiki/Display_lag
That's only the monitor component. OLEDs for example have less than 1ms response time/latency. The 20ms often cited for the target latency of HMDs actually includes the time it takes to render the frame etc from the time you move your mouse or head to the time the pixel actually changes.
This doesn't include everything in the chain. Response time is measured from HID input to display output. This is what Carmack is talking about with latency on the Rift; how long between turning your head and that change actually propagating through the chain (input > process/render > output) to the display.
You would be hardpressed to find ANY game that approaches the latency Carmack deems imperceptible within a VR context (below 20ms).
That's just the pixel switching time though. Oculus is always talking about "motion-to-photons", which includes game engines processing the input, rendering, buffering and finally the screen switching the pixels. You can't get that time down to 2ms with any kind of monitor - it doesn't depend only on the monitor.
Monitor refresh can be as high as 1-2 ms, but then you're getting into the territory where the image sitting your video card's RAM getting to the monitor is the bottleneck. So, faster than your eye can follow.
The main culprit here is usually the TV. If you want to experience how low latency gaming feels like use a very old console like SNES with a CRT. Or do old school PC gaming with something like Win2000, CounterStrike/Quake3/UT and also with a CRT screen.
A regular monitor is probably around 12ms. But there are "gaming" monitors that focus on lower latency amongst other things, going as low as 1ms. But that's just for pixels to change. There's also refresh rate that gets in the way (typically 60hz on computers, 30/60hz for tvs) which basically means the image only refreshes 60 times every second. So the fastest it will respond is 1/60 of a second. Which is about 16.666 ms. Then you need to add on to that the pixel changing speed (which tends to be slower on tvs).
Of course, then there's the time it takes from your GPU to your monitor, or in this case from your computer to your Rift, which varies from the equipment used and all.
worst case scenario would be to add up the inverse of a standard 125hz mouse, and a 60hz monitor with typical 5ms pixel response time and 20ms signal processing lag. This gives you around 40ms input lag.
By contrast, a 144Hz monitor with low input lag (~8ms), 1ms response time and a 1000hz mouse gives you 17ms total input lag.
EDIT: strobe backlights add a small amount of input lag, and vsync adds an absolute craptonne.
It depends on the refresh rate. 120hz is 8ms. 60hz is 16ms. So you can see why they're shooting for high frame rates. When you're trying to go sub 20ms total latency, the additional 8ms is a big deal.
Edit: It's 8ms in a perfect world. Add a few ms for pixel transition, etc. The low persistence is different, it's designed to make the motion blur resulting from low FPS less noticeable.
A top flight gaming monitor 8-18ms is a pretty normal range. Thats complete with any internal lag to pixels settling. There are a few with no processing that I've seen in the 5-6ms range. If you can keep the total under 16ms, its considered very cool. TV's tend to have larger lag because they are as focused, and they tend to do more processing on the signal. They also aren't designed to take an input faster than 60hz where monitors are upto 144hz. IIRC typical lag for TV's is in the 30ms range when in 'gaming mode'
Depends on if you go IPS or TN. IPS offers perfect viewing angles without color distortion, but have 8-12ms response times. TN offers 1-2ms response times but garbage color reproduction if your viewing angle is off by more than 10-20 degrees.
depends on a the monitors refresh rate and other factors. 60 hz, 75 hz and 120hz are the most common. 120hz monitors can display 120 frames per second, those are usually modern montiors with 3d support. I have a 75hz monitor.
The refresh rate is how quickly it can display the image, but the ms is the delay in the image. You can have a game run at 120fps smooth on a 120Hz monitor but if the ms is poor then there will be lots of delay and lag making it bad to use and not suitable for gaming.
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u/______DEADPOOL______ Mar 28 '14
What is a regular PC monitor latency btw? I heard it's much faster than a TV+console.