And the biggest culprits are TAA (Temporal Anti-aliasing), TSR (Temporal Super Resolution), and DLAA (Deep Learning Anti-aliasing)...
... but any effect that accumulates data from past frames is also a problem.
And these effects are becoming standard defaults, often with no way to disable them.
The issue is that these effects cause blurring, subtle shifting, and ghosting, which can be nauseating to people who are sensitive to it (like both my partner and I).
We would love to be able to play games without getting sick.
Alas, they're relatively cheap techniques, processing-wise, with some desirable effects, so I understand why they're used so widely... But maybe they shouldn't be? Or they should have some alternative at least?
I first noticed this while working on an Unreal Engine game
— every playtest completely wrecked me with nausea. At some point, I started spotting the subtle image ghosting and decided to dig into the settings to track it down. After toying with the rendering settings, I accidentally changed the anti-aliasing — it had never registered as a possible culprit, so I never thought to change it.
Lo' and behold tho, the ghosting was gone.
Suddenly, I could last WAY longer during playtests. There were still issues: some other effects still ghosted, we hadn't implemented a setting for view bobbing yet (there was, unfortunately, pushback on this), and we had Field of View distortions going on, but it was a start.
I've been on-and-off looking into the side-effects and claims about temporal effects ever since, and it seems to be a common problem; but it's not obvious, so it doesn't get traction. Instead, so many threads about simulation sickness end with people just giving up because the normal FOV, depth of field, head bobbing, etc... settings cocktails didn't work — and it's left as an exercise for us, as developers, to figure out how many of those were due to temporal visual effects.
Players quit games over this; possibly giving up on entire genres.
Another area where this shows up is reflections: with raycast reflections, and even with some long-standing techniques like cube maps and screen space reflections, you can cut down on their performance impact by rendering different sets of pixels, alternating pixels every frame and combining the frames over time. This also results in ghosting, and when you have reflective surfaces everywhere, it, too, can become a source of simulation sickness.
Is there a fix though?
For the former, I really wish more games would allow for picking between different anti-aliasing methods. If nothing else, disabling them — but many approaches to the latter issue (reflections) rely on TAA to work, unfortunately, so just changing the anti-aliasing mode results in visible artifacts and noise... -That- needs to be fixed.
There's this article by a graphics programmer detailing their explorations here; their conclusion is that you can possibly approximate the quality of TAA with a sharper image by using a hybrid of other non-temporal AA techniques, and get acceptable performance. Specifically for forward renderers, which is limiting.
I think that line of inquiry has merit, however; investigating hybrid approaches would be great for resolving the issue. It doesn't seem like temporal effects are salvageable by their nature - it's the temporal aspect that makes them nauseating, alas.
I'd love to see more honest dialogue around this too
Technical articles either don't acknowledge the problem outside of "ghosting" on its own — which could be otherwise acceptable if only it stayed in the realm of aesthetic aberration instead of veering clear into gut-wrenching torture territory, or such articles outright downplay nausea concerns with claims that "TAA is here to stay, and you have to live with it".
Of course gamers have the best opinions here. Better than any professional. They run the full gamut from denial, to claims about people being too sensitive, "the game just isn't made for you", all the way up to the peak of "git gud". (With the occasional well-reasoned "maybe it should have a toggle")
...
I used to play things like Tribes Ascend in college (a shooter with jetpacks, anti-gravity skates, and hills galore), but now it seems like everything that isn't a top-down isometric game or side-scroller makes me sick. Even after doing all the normal setting fiddling. Now, I wonder how many of these games are using temporal effects (Probably too many, recently...).