Comment by virtualritz | Hacker News Reader

Comment by virtualritz | Hacker News Reader

Parent Full thread

Ofc the human visual system does not work at discrete frames.

However, there is a threshold on how much information your brain can process and tests indicate this maxes out at the temporal detail you can fit into 60 'discrete' frames per sec. For many people it is actually much less.

That is: in general.

Specifically this threshold is differs based on certain variables; the most important one being available light (number of photons per unit of time).

I.e. the less light, the more motion blur there is because there is more temporal integration happening in your brain's visual system. Estimates say your brain goes down to a temporal information density of less than 10 FPS in very low light circumstances [1].

Your brain does perceive motion blurred frames differently. How do I know? I worked in VFX on many blockbuster movies. We do preview stuff using realtime graphics (aka what game engines do) w/o motion blur at equal frame rates as the final frames (which are with motion blur, ofc).

Even on projects where we used 60 fps there is visible strobing w/o motion blur. And as I said: even when you preview stuff at 120 fps or more there is visible strobing with geometry that covers big distances in your FOV.

Motion from game engines w/o motion blur does not least look like game engines because of this. There is also a night and day difference between post-process motion blur, based on 'smearing' the image based on a motion vector pass and true 3D motion blur.

"The Hobbit" triology was done at 60FPS. But it still had motion blur, for obvious reasons.

[1] https://www.sciencedirect.com/science/article/pii/S004269890...

EDIT: typos/grammar

The Hobbit was recorded at 48fps, not 60.

And as I said: even when you preview stuff at 120 fps or more there is visible strobing with geometry that covers big distances in your FOV.

Exactly. The game has no idea what is and isn't moving in my FoV because it doesn't know what I'm looking at, only what the camera is looking at. Subjectively, in my experience, games do a terrible job at predicting what I'm looking at and I'd prefer they stop messing up my experience by trying. Strobing is better than smeary mess.

> The Hobbit was recorded at 48fps, not 60.

True, but it doesn't really change the point.

TLDR; gamers hating motion blur are not hating motion blur. They hate the way its implemented. It's far from the real thing.

The actual misunderstand here is that you are comparing apples to oranges. Motion blur for games is just as good and well-placed as it is for movies.

But only if it is actual true 3D motion blur that mirrors what happens in the real world (as in the parent article of this discussion).

In practice almost all games only blur the camera which blurs everything which leads to gamers then complaining about motion blur (and some even getting motion sickness/headaches).

Simple example: an object moves left accross the frame and the player tracks it while they're strafing fast to the right. Real motion blur means the object has almost zero blur since the player is tracking it (keeping it approx. in his FOV's center) while the BG is heavily blurred because of the strafing move the player is making.

When you only have camera blur, everything, including the tracked object is heavily blurred. That's what most games do and what gamers rightfully hate. But it is not the motion blur you see in film. Some games seem to do better now, I think this is called 'per pixel motion blur' in the games context (but I may be wrong).

> Exactly. The game has no idea what is and isn't moving in my FoV because it doesn't know what I'm looking at [...]

That is valid point if you had true motion blur and wanted to make this even better in a gaming context. See above.

I used to own and play around the FOVE VR headset (their SDK was absolutely terrible at the time and Windows-only, unfortunately, I sold it to a uni eventually) [1].

It had eye tracking. And that is indeed what you'd need to do the motion blur "better" for games where a player tracks fast moving objects accross the frame. Because you will have a slight discrepancy between the tracking of the eyes and the tracking of the look-at direction from motor latency and under-/overshoot.

I.e. calculate the difference in movement of eyes against final transform of geometry (including camera) to calculate how much motion blur you actually need.

For lack of eye-tracking hardware: I wonder if the game could guess what you're looking at and compensate the look-at vector with that to simulate fake eye tracking and get motion blur that is better received by some people.

That is the theory. In practice most games just do the "motion blur" wrong for starters. See above.

[1] https://en.wikipedia.org/wiki/Fove

The Hobbit is interesting in that they made the choice to keep the shutter fully open, essentially maxing out the motion blur slider. It was a controversial choice, I'd argue the wrong one given the many complaints about the imagery during camera movement looking swimmy and indistinct.

Reply on news.ycombinator.com