We need sub-millisecond persistence (<1ms) strobe backlights

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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by Chief Blur Buster » 21 Apr 2014, 19:44

vturksoy wrote:I'll try to do hardware based, refresh syncronized strobing.
Check out the research released publicly at Electronics Hacking: Creating a Strobe Backlight. If you have not read this up, you should read this very thoroughly, in order to understand what is going on.
vturksoy wrote:I'll acsess to hardware and get signals from there and use it to strobe back light. I'll try this on a 65hz screen. More than 65 strobes for each refresh. Do you think that it might work?
Read above. You must strobe only once per refresh.

Explanation Why You Must Strobe Only Once Per Refresh: As you track moving eyes on moving objects on a screen, your eyes are a different position at the beginning of a refresh than at the end of a refresh cycle. This creates the motion blur you see in the demonstration animation at http://www.testufo.com/eyetracking. Your eyes are continuously moving. But the frame is static for the whole refresh cycle. Your eyes are not digital stepper motors, so there's always a disconnect between your continually moving eyes (as you track moving objects on a screen) and the discrete stepping forward of a series of static images on a screen (e.g. series of refresh cycles). This creates the optical illusions you see at http://www.testufo.com/eyetracking (Tip: try the "Checkerboard" illusion). Eliminating this type of motion blur requires you to reduce the amount of time each frame is visible for, all the way from the first visibility of the same frame, to the last visibility of the same frame. So it is critically important, that you must make the frame visibility contiguously brief, aka one strobe per refresh, to minimize motion blur. You could flash multiple times in a short time period, but that would be a waste of brightness with a LED backlight; For efficiency's sake, might as well shine it contiguously for the whole target persistence, since strobed-LED and strobed-OLED persistence is equal to the time from the first visibility of a refresh to the last visibility of a refresh (And multiple strobes means persistence is effectively all the way from the beginning of the first strobe, to the end of the last strobe of the same refresh). If you strobe multiple times for the same frame/refresh while your eyes are moving (while tracking moving objects), your eyes will be in different positions during each strobe, and you get the dreaded multiple-image effect:
30fps@60Hz CRT, creates a double image effect
60fps@120Hz LightBoost creates a double image effect
60fps@180Hz PWM-dimming creates a triple image effect
etc.
EXAMPLE: View http://www.testufo.com on a CRT or LightBoost. You'll instantly understand why you want one strobe per frame.
vturksoy wrote:on a 65hz LCD it strobes 65 times as default.
Your LCD does NOT strobe by default.
It's a continuously shining display, flicker free, strobe free, sample and hold.
See Understanding LCD Refresh Behavior Via High Speed Video.
vturksoy wrote:it equals to 15.4ms motion blur. If I tweak it to strobe 130 times 7.7ms blur. if it strobes 260 times 3.8ms motion blur. 520strobes to 1.8ms motion blur. 1040 strobes to 0.9 ms motion bulur.
It doesn't work that way. You must strobe only once per refresh. Read above.
vturksoy wrote:My LCD is around 400 cd/m² so 325 strobes should give me 3ms presistance and fairly enough light.
Light output of a strobe backlight (without overvoltage boosts, often found in LightBoost) is directly proportional to persistence.
So to reduce motion blur by 75%, you will be limited to 100cd/m2.
And to reduce motion blur by 90%, you will be limited to 40cd/m2.
Based on the CREE X-Lamp specifications, you can usually safely use approximately a 3x-5x overvoltage boost to create approximately 3x brightness, so you could theoretically get 120cd/m2 while eliminating 90% of motion blur.
vturksoy wrote:Should I always multiply hz with X to have a proper strobe number? or can I set it to any value?
One strobe per refresh. Read above.
vturksoy wrote:What if I remove the reflective surface on the back of the LCD and add more strobing leds on the back of the LCD ( a proper small box can be made with proper difusers to have even light.)
I do not recommend this. Efficiency of a backlight is extremely poor.
Instead, I recommend boost voltages instead, already found in a section of http://www.blurbusters.com/faq/creating ... -backlight

For your experiment I recommend a good target is approximately 80% motion blur elimination, which will give you 80cd/m2 out of 400cd/m2, then using boost to raise the 80cd/m2 back to 240cd/m2. This is still dramatic motion blur eliminaton on a smartphone, as it will suddenly look like a (65 x 5) = 325fps@325Hz motion clarity when viewing 65fps@65Hz scrolling at 1/5th persistence (1/5th of 1/65sec equals 1/325sec persistence, an 80% motion blur reduction -- using 65 strobe flashes of 1/325sec each, voltage-boosted to 3-5x wattage, for an approximately effective 240cd/m2 average brightness with 80% motion blur reduction.

"OPTIONAL (Advanced): Use boost voltage during flashes. If you have advanced knowledge of electronics, use boost pulses to overvolt the LED backlight so it flashes brighter during pulses. You will be able to gain at least 2x or 3x brightness, but with some accelerated wear and tear on the LED’s. Good study material for reading is CREE: Pulsed Over-Current Driving of Cree® XLamp® LEDs: Information and Cautions. LightBoost monitors actually also do this (albiet to a lesser extent) to compensate for the darkness between strobes, as discovered by Marc Repnow’s reverse engineering of LightBoost. Optionally, you can also add adjustable capacitor softening of strobes for CRT-style phosphor decay, to make the 60Hz flickering slightly less harsh.
vturksoy wrote:Second plan is just to open reflective surface from led light side just enough to add another 12 set of leds with same specs. (double led row)
Intensifying an edgelight is a lot easier than converting an edgelight to a backlight. However, I suggest the simpler voltage-boost method first, to see if you can get satisfactory performance. Remember, the 65Hz->"equivalence 325Hz" upgrade (even at 240cd/m2 voltage boosted) will be a much bigger upgrade than "60Hz->65Hz". You don't have to target ultrashort persistence such as 0.5ms or 1.0ms, when just merely having 3ms or 4ms persistence gives you the world's lowest-persistence smartphone.

If you succeed in your modification, we'd love to feature you on Blur Busters. This talk is definitely "Area 51" worthy.
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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by vturksoy » 21 Apr 2014, 21:20

Thank you very much for your informations. I'll be happy to share If I can sucseed. But it's "Area 51" untill sucseeded. I can't tell you more on here but I can PM to you.
Let me do the math for 60hz to see If I got it.
lets use %90 motion blur elimination on 60hz this gives me 600fps@600hz motion clarity 1/10th of 1/60 = 1/600sec 1,6ms strobe lenght 1,6ms presistance.

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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by Chief Blur Buster » 21 Apr 2014, 21:45

You're welcome to send me a PM, or email [email protected] --

Is this a hobby project or a commercial project? I also offer consulting services (regarding my low-persistence knowledge) to vendors needing to understand the art of eliminating motion blur, if this is a commercial project that you are currently doing.

If you are aiming for 90% motion blur elimination, using voltage boosting on the existing LCD edgelight, you'll be targetting 100-120cd/m2(averaged) on a 400cd/m2(steady) backlight. (400cd/m2 then a 90% loss to 40cd/m2 during eliminating 90% of motion blur, then overvoltage boosted back upwards to 100-120cd/m2). That would be 1/650sec strobes at 65Hz. I would however recommend 1/600sec strobes at 60Hz, because that will look a LOT better for video games, because 60fps@65fps looks terrible, while framerate==stroberate==refreshrate during 60fps games and videos, will look a LOT better. On the other hand, if you can easily switch refresh rates on the fly between 60Hz and 65Hz, provide that option too. Flexible refresh rates and flexible persistence is very desirable among power users.

I highly recommend you make it adjustable strobe length (adjustable persistence). It should be as easy as writing a register or command. An example is BENQ Blur Reduction in Z-Series monitors -- http://www.blurbusters.com/strobe-utility -- have strobe flash lengths adjustable from 0.5ms through 5.0ms. Obviously, 5.0ms is about 10x brighter than 0.5ms, so it's a brightness versus clarity tradeoff.

Even if it doesn't already succeed, merely talking about this is still worthy of discussion in the "Area51" forum here on Blur Busters, so there's a thread redirect added there already.
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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by vturksoy » 21 Apr 2014, 23:46

This is do the best you could project, which could turn to a commerical project. If it becomes such a project I'm more than happy to get your help further.
I'll share the results when done.

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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by Chief Blur Buster » 21 Apr 2014, 23:54

Buying a high speed camera and pointing the smartphone web browser at http://www.testufo.com/flicker (Full Screen) could give you important data on whether the LCD is cleanly strobeable or not. See example videos -- they're just high speed videos of http://www.testufo.com/flicker

Another potential issue you may run into, is the too-small blanking interval between refreshes, relative to a slow LCD pixel transition time. Study the BENQ Blur Reduction forum and the "Vertical Total 1350" tricks (VT1350) which is the technique of accelerating the LCD scanout, to create longer pauses between refreshes, in order for more time for LCD GtG pixel transitions to settle before strobing the backlight.

If you have a slow smartphone LCD that takes 8ms, you might have a hell of a lot of strobe crosstalk (double image effects), unless you can accelerate the scanout to create large 8ms pauses between refreshes. During 60Hz, that means scanning-out of the LCD in 8ms, followed by a long 8ms pause between refreshes, during a 16.7ms (60Hz) refresh cycle. Doing all of this might be challenging, as you were only able to overclock to 1/65sec scanout rather than 1/120sec scanout. Good strobe backlights on fast LCDs have almost no strobe crosstalk for the center band across the screen, and still has some strobe crosstalk at the top/bottom edges of the screen.

At the very minimum, you should already own at least one modern-era 120Hz computer monitor with a strobe-backlight (e.g. LightBoost, ULMB, Turbo240, or BENQ Blur Reduction) in order to gain an understanding of how high-efficiency strobe backlights function. I am assuming you already own one of those.

Also, you should be aware that the OLED in the Oculus VR goggles is already a low-persistence OLED, run as a rolling scan (e.g. info #1). From what they said in a media interview, it is a "smartphone industry leftover", so you should also investigate modifying an OLED smartphone to do a rolling scan. Essentially running a chasing "off" pass scan following behind an "on" scan pass on the OLED. Low persistence can be pixel-based (one strobe flash per cycle per pixel), or global-based; it doesn't have to be all pixels all at once, as long begin-to-end illumination time period of each pixel is shortened.

Strobes don't have to be global (all at once like a strobe backlight), but sequentially scanned from top to bottom. Just avoid multiscanning (that creates stationary tearline artifacts), illustrated as disjoints in scrolling marquee banners in the Charles Poynton paper at http://www.blurbusters.com/references/ (most specifically this 1996 paper).
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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by 90180360 » 07 Jun 2014, 06:32

I finally got my VG248QE (still waiting for the DIY KIT) and one of the first things I did was play HL2 120fps@120Hz with LightBoost (10% brightness).

Completely amazing experience obviously, if only I didn't have to look at a monitor, but could step into this world! (Luckily DK2 is coming soon!)
Chief Blur Buster wrote:We need sub-millisecond persistence (<1ms) strobe backlights
Chief Blur Buster wrote:Fast flick mouse turns at several thousand pixels per second panning.
To be honest I don't think the 1.4ms (or even the 2.8ms at 100%) persistence are the big problem. The 120fps@120Hz are!

Correct me if I'm wrong, but motion blur due to persistence only applies to objects your eyes track across the screen.

Let's say I do a 180 degree turn in 0.5 seconds. Assuming 1080p and 90 degree FOV that's 4320 pixels per second if my math if correct. My eyes aren't tracking anything during that turn. Truth be told, they already struggle to track the UFO at 3840 pixels per second.

What my eyes see instead, are several 100% blur free images of the rotating scene at 36 pixels (4320/120) distance or of the UFO at 32 pixels (3840/120) distance respectively. So we have the problem of individual images being dozens of pixels apart yet we worry about 1 or 2 pixels of motion blur?

Obviously we need 10,000fps@10,000Hz :lol:

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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by Chief Blur Buster » 07 Jun 2014, 12:26

90180360 wrote:What my eyes see instead, are several 100% blur free images of the rotating scene at 36 pixels (4320/120) distance or of the UFO at 32 pixels (3840/120) distance respectively. So we have the problem of individual images being dozens of pixels apart yet we worry about 1 or 2 pixels of motion blur?
Yep, that's the stroboscopic effect of the discrete refreshes, which is actually still visible all the way to thousands of Hz. Michael Abrash also talked about this in Down The Vr Rabbit Hole: Fixing Judder. I discussed this in Area 51, in the What Refresh Rate Do We Need? thread. It is commonly known as the "mousedropping effect" too, when spinning mouse cursor around in circles on a black background while staring stationary. Many vision researchers are very familiar with this issue. The most relevant post describing the exact effect you describe.
Mark Rejhon wrote:Excellent observations!
Your first post is definitely "Area 51" worthy, and also welcome to Blur Busters Forums!
For other readers reading this, I consider this post "Chief Blur Buster" approved -- the kind of stuff we like to talk about!

You certainly did your homework, and all your observations are pretty accurate (I should ask you to be a guest writer for Blur Busters).
.
There are some additional factors where one may require well beyond 75Hz, and possibly far beyond (e.g. 1000Hz), include the stroboscopic effect. (See Why We Need 1000fps @ 1000Hz This Century).

Several sources of what you wrote already explains this, but here's a good demonstration:
View http://www.testufo.com/photo#photo=eiffel.jpg which I've embedded below using the [testufo] tag.

Stare at a stationary point in the middle of the top edge of this moving animation.
------------------------------------------------------v--------------------------------------------------------------


1. Put your finger at the top edge of this animation. Keep the finger stationary.
2. Stare at your finger (or next to your finger). Keep your eyes and finger stationary.
3. As the antenna part of Eiffel tower scrolls under your finger, you will see multiple antennas appear
(the stroboscopic effect -- kind of like the reverse version of the phantom array effect -- stationary eye but a series of static images that represent moving object at a finite refresh rate)
4. This problem is most pronounced at 60Hz (e.g. antennas 16 pixels apart at 960 pixels/second)
5. This problem still exists at 120Hz (e.g. antennas 8 pixels apart at 960 pixels/second)

This will work even on the slowest laptop LCD panels, too.

Same kind of situation occurs when you spin your mouse pointer in a circle on a black background, it's not a continuous blur, even a 1000Hz mouse will show up only 120 'copies' of cursor per second (at 120Hz refresh rate) when you spin the mouse pointer rapidly in a circle on a black background while you stare stationary in the middle of your monitor (this is also known as the 'mousedropping' effect).

The only way to eliminate all stroboscopic effects like this, without adding motion blur back, is to do flicker-free persistence at ultrahigh frame rates (either by interpolation, but preferably real frames), so that there's continuous motion rather than static frames that can cause stroboscopic interactions (phantom array, mouse dropping effect, wagonwheel effect, etc).

You can add (1/fps)th millisecond worth of intentional/artifical motion blur to mask this effect, much like movies do (35mm film), in order to fix the strobing, filmmakers add intentional motion blur. For example, at 1000 pixels/second and 16 pixel step per frame (60Hz), you could add 16 pixels of intentional GPU-effect motion blurring, to eliminate this stroboscopic effect.

However, adding motion blur is very bad when you want to simulate virtual reality (as both you and I already know, from John Carmack's talks, and Oculus). For this use case, you want 100% of all motion blur to be 100% natural, created inside the human brain, if possible -- no externally added motion blur as a band-aid. Also, motion blur is undesirable by a lot of readers on Blur Busters, who come to this very site, in the pursuit of elimination of motion blur. So someday into the future, we'd want to attempt to do strobefree low-persistence. To do 1ms persistence without flicker/strobing/phosphor/etc, you need to fill all 1ms timeslots in a second, and that means 1000fps@1000Hz to achieve low-persistence with no form of light modulation. That, as you can guess, is quite hard to do with today's technology, so strobing is a lot easier.

75Hz completely solves the motion blur problem by allowing low persistence above flicker fusion threshold. However, it doesn't solve 100% of the problem of making virtual imagery completely indistinguishable from real life. Certainly, it's often "good enough", and it will have to be good enough for the next decades (or few), probably.

There is a Law of Persistence: 1ms of persistence (strobe length) translates to 1 pixel of motion blurring during 1000 pixels/second. Decay curves (e.g. phosphor) complicate the math, but strobe backlights such as LightBoost, ULMB, BENQ Blur Reduction are essentially near-squarewave and very accurately follow this Law, to the point where I've begun to call this "Blur Busters Law of Persistence". This does make some assumptions (no other weak links, stutter free, frame rate matching refresh rate, perfect smooth VSYNC ON motion such as stutterfree TestUFO motion, motionspeed that are slow enough that random eye saccades are an insignificant motion factor). I find I can track eyes accurately on moving objects on screen (i.e. ability to count eyes in the TestUFO alien, which are single pixels), up to approximately 3000 pixels/second from arm's length away from a 24" monitor. Different humans will have different eye tracking speeds, but this kind of defines the bottom end persistence that we need, since 1ms of persistence at 3000 pixels/second blurs the eyes to 3 pixels wide rather than 1 pixel. This is the reason why I told BENQ to support 0.5ms strobewidth in their new firmware (they listened; now we just have to wait for the fixed XL2720Z firmwares to ship), since I apparently can just about barely detect the motion clarity difference between 0.5ms persistence (strobelength) and 1.0ms persistence (strobelength). For 1080p 24" at arm's length away, most people track reasonably accurately at 960 pixels/second. Others, track at 2000 pixels/second before eye tracking can't keep up. I find I cap out approximately at that motionspeed. During 3000 pixels/second TestUFO animations, this means the difference between 1.5 pixels of motion blurring (insignificant blurring at http://www.testufo.com/ghosting#pps=3000 or http://www.testufo.com/photo#pps=3000 ) versus 3.0 pixels of motion blurring (alien eyes blurred at http://www.testufo.com/ghosting#pps=3000 as well as windowframes of buildings blurred at http://www.testufo.com/photo#pps=3000 )... I have this beta firmware installed on my XL2720Z, and it confirmed my findings: 1ms persistence is not the final frontier. So, I recommend manufacturers start considering 0.5ms persistence, and not stop at 1.0ms persistence. This will become even more demanding in the VR era, during panning during fast head-turning speeds, and 4K screens (twice as many pixels to track across), so 0.25ms might actually produce a human noticeable improvement over 0.5ms. (e.g. 8000 pixels/second during slow head turning -- creating 2 pixels versus 4 pixels of motion blur during 0.25ms persistence versus 0.5ms persistence). For now, 1ms persistence (LightBoost 10%) is sufficiently low to satisfy the majority of population, as you still get a lot of brightness loss trying to achieve lower persistence, and compensating with brighter strobes gets expensive (oe.g. custom backlights/edgelights). That said, you can still just do 75Hz, with say, 0.25ms persistence and call it a day, unless you were concerned about stroboscopic effects.

We are stuck with stroboscopic effects, ever since humankind invented the concept of frame rates / refresh rates when we came out with zoetropes and kinetoscopes of the 19th century, we have never yet been able to successfully record and playback continuous motion naturally in a framerateless manner, so we have the artifical invention of the frame rate for now -- since it's the easiest way to virtually represent motion.

The lighting industry has done several studies about human detection of stroboscopic effects of flickering light sources (it's a good reason why fluorescent ballasts have gone electronic and often use >10KHz rather than strobing at 120Hz). The stroboscopic-effect detection threshold (phantom array detection) can be quite high, even 10,000Hz for a portion of human population -- see this lighting industry paper, so that will define roughly the refreshrate we need, although we could get by with just 1000fps@1000Hz + 1ms of motion GPU-effect blurring (fairly imperceptible, but enough to prevent wagonwheel effect).

Image

I totally agree with the individuals such as those in Valve Industry and Oculus, about the elimination of the vast majority of artifacts during low-persistence >75Hz -- this is definitely the sweet spot, as you've described. By all means, it doesn't completely eliminate all differences between virtual imagery and real-life imagery, we still will need >1000fps@1000Hz to pull off the "real life indistinguishability" feat, or some kind of future framerateless continuous-motion display, even a display that refreshes faster only where the eye is staring at, etc. By going to low persistence via strobing, we solve a large number of VR problems, just that low persistence using today's technology necessitates strobing and that problem is unsolvable without going to ultrahigh framerates. (0.5ms = 2000fps@2000Hz needed for flickerfree low persistence with zero strobing, zero light modulation)

Corollary/TLDR: As you said, low-persistence 75Hz+ is definitely the sweet spot that solves a lot of problems. However 75Hz is still not enough to pass a theoretical Holodeck Turing Test, "Wow, I didn't know I was standing in Holodeck. I thought I was standing in real life.", because there still remain side effects of finite framerates, that cause motion to not fully mimic the completely step-free continuous motion of real life (no judder, no stutter, no wagonwheel artifact, no blur, no strobing, no visible harmonics between framerate vs refreshrate, no phantom array, no mousedropping effect). To do so via finite refresh rate, we need ultrahigh framerates synchronized to ultrahigh refrehsrates, 4-digit, in order to completely solve all possible human-detectable side effects of a finite frame rate, achieving low persistence via continuous light output, without strobing/phosphor/light modulation, to achieve simultaneously completely stepfree, strobefree, and blurfree motion necessary to mimic real life.

Very interesting talk though -- and we need more people like you, visiting this brand new forum which launched barely more than a month ago!

Also, here's photos of the Eiffel Tower Test. You stare stationary at the screen while the eiffel tower scrolls past. Less strobe effect. The same problem occurs on any finite-refresh-rate display (CRT, LCD, plasma, whatever).

Image

Image

The same problem occurs for CRT and LCD, strobed and non-strobed, flicker and flickerfree, phosphor and phosphorless.
90180360 wrote:Obviously we need 10,000fps@10,000Hz :lol:
That would certainly eliminate the visible stroboscopic effects / wagonwheel effects.
Unfortunately, it probably won't happen this century, but 1000 Hz is realistic. The ability to do true-500Hz and true-1000Hz is already occuring in vision research laboratories, and Viewpixx already sells a true-500Hz projector. Although this really pushes diminishing points of returns for human side effects of finite refresh rates, stroboscopic effects of refresh rates (even on sample-and-hold displays -- due to the gapping effect during stationary-eye-moving=image situation). still prevent perfect "real-life immersion".

Adding artificial motion blur (GPU effect) to fill the stepping between refreshes also fixes the stroboscopic problem at the cost of added blur. But additional motion blur (above-and-beyond human vision limits) is quite undesirable for virtual reality applications where you need 100% immersion all the way to natural human vision limits, in every single artifact department (including strobe artifacts that still exist even on a 1000Hz laboratory display). At 1000fps@1000Hz, you could add just an ultra-tiny amount of motion blur to fix the stroboscopic/mousedropping effect. But even this 1ms blurring is still noticeable during head turning in virtual reality!
90180360 wrote:Correct me if I'm wrong, but motion blur due to persistence only applies to objects your eyes track across the screen.
That is definitely correct. Persistence-related blurring only occurs when eye motion is out-of-sync with image motion. It's well demonstrated at the motion blur animation at www.testufo.com/eyetracking where you don't see the blurring when staring stationary.

That's why LightBoost/strobing doesn't help you if you only stare stationary at crosshairs at all times. So LightBoost/strobing only helps certain gameplay tactics that require tracking eyes, e.g. killing many enemies in fast-twitch manner, circle-strafing, high-speed low flybys over camoflaged areas, platformer game scrolling (Super Mario style), and any situations that gives you an advantage during eye-tracking situations.
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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by 90180360 » 07 Jun 2014, 16:50

Thanks for the detailed response.
Chief Blur Buster wrote:Adding artificial motion blur (GPU effect) to fill the stepping between refreshes also fixes the stroboscopic problem at the cost of added blur.
Would it really fix it, though? From what I understand, even stationary objects can strobe, on a low persistence display, if your eye is tracking something that moves past them.

What we need for CV1 is eye tracking and low persistence only for what's currently being tracked and full persistence with some artificial blur for everything else :D

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Re: We need sub-millisecond persistence (<1ms) strobe backli

Post by Chief Blur Buster » 07 Jun 2014, 17:25

90180360 wrote:Would it really fix it, though?
At 1000fps@1000Hz, you don't need strobing. 1ms persistence via 1ms strobe is the same amount of motion blurring as 1000fps@1000Hz strobe-free.

But even if you strobe, it depends on how the eye moves independently of the display plane. But in the stationary-eye-moving-objects, artificial motion blur in the moving objects, will definitely "fill in the gaps" even with LightBoost. For example, just play VSYNC ON 120fps@120Hz Source Engine game, with GPU motion blur effect enabled, and you won't see the stroboscopic effect anymore even with LightBoost enabled (assuming full 120fps@120Hz VSYNC ON perfect synchronized framerate double-buffered, not triple-buffered, and the eye is not moving).

Now, if you started moving eyes (e.g. moving eyes upwards, while objects moved towards to the right), then the stroboscopic effect can come back during LightBoost. However, with GPU motion blur effect enabled, the stroboscopic effect disappears during LightBoost for the stationary-eye-moving-object situation during perfectly synchronized framerate-refreshrate situations.
90180360 wrote:What we need for CV1 is eye tracking and low persistence only for what's currently being tracked and fully persistence with some artificial blur for everything else :D
Unfortunately, probably not practical to adjust GPU motion blur effects "on the fly" based on eye tracking. Adjusting GPU motion blur effects based on eye tracking could help, but the problem with that is you need very low latency (e.g. 0.1ms eye tracking input lag), otherwise, you get motion blur distortions.

Besides, if you're tracking, then low persistence solves the problem -- and if your eyes are stationary, GPU motion blur effect filling the gaps between refreshes solves the stroboscopic problem. Unfortunately the blur problem and the stroboscopic problem, are separate problems, and is unfixable without a high refreshrate / high pollrate.

Even Oculus agrees too about the 1000fps@1000Hz (or beyond) being needed to simultaneously solve the stroboscopic problem AND motion blur problem (at the same time) from Palmer Luckey:
Palmer Luckey wrote:...You couldn’t have a made a low-persistence VR headset five years ago at all and certainly not well. It’s going to be mandatory for a good VR experience going into the future until we can get displays that run so fast that a single full-persistence frame is as short as our low-persistence flash. You’d need to get up to 1000 frames per second to do that. Until we have 1000 Hz displays, 1000 fps rendering, and some hypothetical, crazy video link with hundreds of more bandwidth than HDMI, we’re going to be stuck with other solutions.
...from Popular Mechanis interview with Palmer Luckey of Oculus
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