While a good personal experience sample -- I just want to point out that you missed a very important point about widest-population satisfaction (which is definitely not opinion, but actual research).MCLV wrote: ↑29 Mar 2021, 15:52I think it really depends on the application. I'm not sure that it's so clear cut and that uncanny value is always that wide. 24 fps has definitely it's own look but I have to say that I've never considered it good looking in certain situations, e.g. panning shots. I made my own comparison of 24, 30, 60 and 120 fps video few weeks ago. 24 fps looks great when camera is static but falls apart during panning. Higher framerates look progressively better during panning. However, it was not completely apples-to-apples comparison since I recorded 24 and 30 fps in 4K and 60 and 120 fps only in 1080p. Unfortunately, I don't own any device capable of recording 4K at 120 fps.
For engineering the entire display experience for the population, this is not one of the situations where you can use only one person's personal experience. This is a human population based matter.
Consider the use case of staring at a huge IMAX screen. Consider the people who get motion blur nausea.
To get as much five-sigma comfort as possible (least numbers of motion sick from the widest numbers of human population), you have to push the framerate really low OR really high.
The % of motion sickness cases increases with wide-FOV intermediate-framerate sample-and-hold HFR because you're getting a wide reallife FOV, but you're still getting camera motion blur or display motion blur enforced upon your human eyes.
This was traced the fact that motion is now smooth (no stutter / edge flicker) to help you suspend disbelief, but now you're eyetracking still-blurry motion.
It doesn't mean the satisfaction rating of a one-person sample (like you) when it comes to sample-and-hold HFR. Motion-blur-nausea and motion-blur-induced motion sickness is getting more well known in the last few years, and is Elementary VR Comfort 101 now -- any good VR researcher know about this already.
Since people started wearing the first Oculus Kickstarter VR headsets and got puke/sickness from sample-and-hold, but magically disappeared when Oculus strobed the display.
For the Motion Blur Uncanny Valley Effect, Set Variables To The Following
Size = Wide Field-Of-Vision (FOV) Displays (VR, IMAX, simulator rides, sit close to screen, etc)
Tech = Sample and Hold (LCD, OLED without strobe/flicker/BFI/PWM-free/impulsing)
Resolution = Retina (4K and up)
Sample = Human Population
Goal = Satisfy Widest % Without Motion Blur Nausea
When these variables are configured, the motion-nausea uncanny valley effect appears. The best display comfort (lowest % of motion sickness) occured at these:
- Low frame rates (i.e. 24fps)
- Ultra high frame rates (i.e. 500fps or 1000fps+)
Unless you changed the "Tech" variable to strobing the display (e.g. 120fps at 120Hz), to fix persistence motion blur of 120fps HFR.
Reports of dizziness, headaches, nausea, were pretty common during head turns on the original Oculus Kickstarter DK1 VR headsets (sample-and-hold VR), until the Oculus Development Kit 2 (strobed pulsed OLED) and the first Oculus Rift CV1 units, where strobing added another order of magnitude (or two) reduction in population discomfort of VR. The same effect is also observed for other kinds of wide-FOV displays other than VR, too.
Some will always get motion sick, but smaller % of population does at the ultralow and ultrahigh ends, with these variables, reduced motion sickness from the immersion-disengage-effect of low frame rates, and reduced motion sickness from blurless flickerless motion (from ultra high frame rate low-persistence sample-and-hold).
This is why 24fps and 1000fps has fewer headaches than 120fps sample-and-hold HFR (where you still had a mandatory 1/120sec = 8.3ms of display persistence = 8.3 pixels of guaranteed minimum motion blur per 1000 pixels/second = 64 pixels of motion blur during one screenwidth per second panning on 8K sample-and-hold display for 120fps HFR.
When you need to design something you need to sell to the wide-FOV market (VR, IMAX, ride simulator, etc) and you don't want your population to become dizzy, then what I am saying here is exceedingly critical -- it's already mandatory VR Engineering 101.
Today, thanks to switching from sample-and-hold to strobed/pulsed operation, modern VR has now become much comfortable than cinema 3D glasses, and almost anybody can put on a VR headset for an Oculus "Comfortable-rated" app (i.e. virtual lounger on virtual beach, rather than sitting on a rollercoaster), and have far less discomfort than watching a 3D cinema movie with traditional polarized glasses. The motion blur (even of 90fps or 120fps HFR) was the bigger motion-sickness poison relative to the flicker of strobing.
This stuff is so recently studied that new research papers are still being written for the first time on this, but needlessto say, it is currently now widely known in the VR-headset researcher community.
So for large-population comfort for wide-FOV use cases:
- Extremely low frame rate sample-and-hold (like 24fps cinema/IMAX/ridesim screens)
- Ultrahigh frame rate sample-and-hold (low persistence without strobing)
- Strobed framerate=Hz beyond flicker fusion threshold (low persistence via strobing)
There will always be people who always gets motion sick, but a smaller % of humans gets motion sick when you push framerates lower or higher on sample-and-hold displays, due to "motion is smooth but still blurry" odd effect.
Remember, also, not every human eyes or brain sees the same. Prescription glasses. Color blindness of varying degrees. More sensitivity to stutter than blur. More sensitivity to blur than flicker. More sensitivity to flicker than blur. Brain-processing quirks such as dyslexia (or the motion-sensitivity brain processing flaws such as the varying degrees of Akinetopsia). Different color primaries (e.g. one human seeing brightest red at +10nm different primary than the next human; remember color gamut standards are based off an average human's primary color abilities, but even non-colorblind humans sees colors ever slightly different from next human, like no two snowflakes are perfectly identical). Vertigo (eye-hand-coordination problems). Brightness oversensitivity. Headaches from excess contrast or bright colors. Etc. Etc. There's so many quirks by humans from displays being imperfect simulations of real life.
Sometimes, we have try our goddamndest best to five-sigma display comfort. (Five-sigma tends to be impossible, it's more like three-sigma, but always perpetually refineable)
Wide-FOV blends a display into real-life, and when a display does not match real life (i.e. display persistence blur above-and-beyond human vision/brain limits), a larger percentage of humans gets dizzy/nausea. The low frame rate makes it easier to decouple dispay-vs-real-life. But once frame rates starts going high enough (60fps) where the stutter-to-blur continuum becomes blur instead of stutter -- the human brain starts processing a wide-FOV display as if it's real life. But sample-and-hold HFR (even at 120fps) still has stupendous amounts of motion blur (also amplified by Vicious Cycle Effect), which becomes a major problem for high resolution wide-FOV displays. Thus, "motion is perfectly smooth" + "motion has motion blur" = very oddly different from real life. Not good for VR/IMAX/ridesim/cinema first-row-of-seats/etc use cases -- cue the mandatory barf bags for roughly 10x-100x more population than would otherwise be with optimized motion.
Although it's very complex with lots of interacting causes, these are confirmed:
- There are some who gets discomfort from flicker
You need sample-and-hold, but that adds blur
. - There are some who gets discomfort from motion blur
You need low persistence (either via flicker/impulsing, or via ultra high framerate sample-and-hold)
Sample-and-hold 120fps HFR still has guaranteed display motion blur
. - There are some who gets discomfort from both (sensitive to flicker, AND sensitive to motion blur)
You need low persistence sample-and-hold via ultra high framerates (e.g. 1000fps at 1000Hz)
Also, there are even cases where adding motion blur fixed some people's display discomfort too -- such as by sheer low frame rate combined with long camera exposure per frame (24fps...). It was recently noticed that the comfort curve has a valley at intermediate sample-and-hold HFR frame rates where you maximize % of display discomfort for wide-FOV displays.
Many researchers I know have actual population-sampling experience in this motion blur headaches topic matter of Blur Busters naming fame -- not so coincidentally, almost a decade ago, I chose the name "Blur Busters", based on science/research/study.
Do you have any nirvana bliss modern-VR low persistence experience (i.e. Rift, Vive, Index, Quest 2 or modern comfortable-VR headsets) and have also compared it to say Zelda VR with Labo VR (large amounts of motion blur nausea from sample-and-hold Nintendo Switch) or iPhone Cardboard VR (large amounts of motion blur nausea too)? In these, do things like head turning (which forces a VR screen to pan).
You don't want to get dizzy during head turns because real world went screwy/odd (extra blur beyond human vision/brain) during head movements. The same problem also occurs for non-VR wide-FOV situations, though becomes progressively less of a problem the smaller FOV you go (less immersive situations). At 30-degrees FOV (arm's length from gaming monitor) or less (couch-far-from-average-TV), sample-and-hold HFR is far less of a problem (smaller population differences in motion sickness ratings).
Obviously there's vertigo causes (e.g. sitting on a virtual roller coaster but not feeling G-forces), but many VR apps are just perfect 6dof sync (e.g. walking around a virtual table that doesn't exist, and leaning down to inspect the bottom surface of the table), and those perfect 6dof sync'd VR apps create no nausea (on 120Hz strobed VR headsets), even for most people who get dizzy watching 3D films at the cinema. The strobe rate is high enough to be beyond most flicker sensitivity, the stroboscopic effects aren't too objectionable, the motion blur is gone, and the vertigo-solve of perfect 6dof sync (1:1 real:vr sync), etc. But a few % still get nausea from the VR flicker (even at 120Hz) but more % get nausea if we turn off the motion-blur-killing VR flicker, we get more nauseating sample-and-hold blurring (120fps HFR blur), whether for head turns (e.g. turning head left/right), or for staring at moving scenery (e.g. looking out of a window while sitting on a virtual train in VR).
Google Fu on academic search engines will still sometimes fail as this is a very new area of research but terms can include "virtual reality motion blur" as well as "virtual reality sickness" and you'll notice the due diligence that is consistent with my writings.