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Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

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Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#71

Post by Daub »

I teach 3D modelling and rendering and also drawing and oil painting.

Many time in my traditional media classes I will use the term ambient occlusion (AO) and describe it in exactly the same way as I would to my 3D class. Specifically, I ask them to imagine being surrounded by a sphere of even light. In such a case, where would the shadows be? I follow this by discussing contact shadow (e.g. the dark line between your hands as they are placed together) and core shadow (e.g. the darkness of your nostrils). In 3D rendering, both these classes of shadows are served by the AO pass.

Certainly, I would say that AO is a natural phenomenon, but it is also an effect that can be used to sweeten the naturally flat effect of a raster engine like Eevee.

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#72

Post by zlsa »

cosmic_cheese wrote: post #28
nananana9 wrote: post #24

Earlier quoted context omitted.

The jitter is because it's usually rendered at 50% resolution - you can render it at full framebuffer size and it doesn't jitter but it's kind of hard to justify.

That might be part of it, but the effect I’m describing includes the shading changing shape. So for example if a bust on a pillar is sitting in a corner, as the camera pans around the bust, AO behind the bust shifts to “wrap” around the edges of the bust which looks strange because no shadow in the real world acts like that.

This is largely because early screen-space AO techniques weren't able to accurately estimate whether the pillar is freestanding (and shouldn't darken the wall) or if it is against the wall (and should darken the wall.)

Modern real-time ambient occlusion techniques can estimate the depth far more accurately and produce correspondingly more believable results, at the cost of performance.

https://www.researchgate.net/figure/Visual-comparison-of-dif...

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#73

Post by avereveard »

Terr_ wrote: post #42
astrobe_ wrote: post #39

Earlier quoted context omitted.

Tangential, but sometimes real images can also seem unreal. I remember seeing a photo of Earth and the Moon with the Moon on the foreground that looked like a bad CGI. But it was actually a photograph taken by a space probe. Or, one can think about those photos of the Apollo lunar module that looked "wrong" (and probably helped some conspiracy theories spread), but were obviously correct - just there's no atmosphere…

Condensed rant: Humans are blind to the most common gasses on our atmosphere (N2, O2) and sometimes have difficulty perceiving its most common liquid (H2O). This is sensible, since otherwise we'd be helplessly wandering through "visible" fog to fall off cliffs or be eaten by giant carnivorous bats. Our "colors" are mostly a quirk of where we're from. Now suppose some aliens arrived at our planet and said: "Wow, your…

these materials are transparent to light it is not a property of the human vision system that light goes trough N2

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#74

Post by thaumasiotes »

Terr_ wrote: post #53
dcrazy wrote: post #20

Earlier quoted context omitted.

I’m not on the ARC Raiders art team, nor have I even played the game. But I can say with some confidence that what people react to in computer graphics isn’t realism per se, it’s verisimilitude .

Right, too many games pitch the "realism" of "really like a Hollywood movie", reproducing effects which are really telltale flaws in cameras, microphones, or the theater-experience. This is in contrast to the realism of "if you were there in person". If you step outside and look towards the sun and see lens-flares, consult an eye-doctor. If you see polyhedral lens-flares or bokeh... consult a roboticist.

> If you see polyhedral lens-flares or bokeh... consult a roboticist.

It's not just games. I just saw an episode of a TV show in which two people were sitting in a car, talking to each other.

Whichever one of them was speaking was in focus. The other one was dramatically blurred. This traded back and forth rapidly, because that's how conversations work. It was incredibly bizarre.

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#75

Post by Terr_ »

thaumasiotes wrote: post #74
Terr_ wrote: post #53

Earlier quoted context omitted.

Right, too many games pitch the "realism" of "really like a Hollywood movie", reproducing effects which are really telltale flaws in cameras, microphones, or the theater-experience. This is in contrast to the realism of "if you were there in person". If you step outside and look towards the sun and see lens-flares, consult an eye-doctor. If you see polyhedral lens-flares or bokeh... consult a roboticist.

> If you see polyhedral lens-flares or bokeh... consult a roboticist. It's not just games. I just saw an episode of a TV show in which two people were sitting in a car, talking to each other. Whichever one of them was speaking was in focus. The other one was dramatically blurred. This traded back and forth rapidly, because that's how conversations work. It was incredibly bizarre.

[dead]

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#76

Post by 7jjjjjjj »

avereveard wrote: post #73
Terr_ wrote: post #42

Earlier quoted context omitted.

Condensed rant: Humans are blind to the most common gasses on our atmosphere (N2, O2) and sometimes have difficulty perceiving its most common liquid (H2O). This is sensible, since otherwise we'd be helplessly wandering through "visible" fog to fall off cliffs or be eaten by giant carnivorous bats. Our "colors" are mostly a quirk of where we're from. Now suppose some aliens arrived at our planet and said: "Wow, your…

these materials are transparent to light it is not a property of the human vision system that light goes trough N2

These materials are transparent to some light. They absorb a lot of infrared and ultraviolet. The human vision system can see the light that isn't absorbed and as a result is abundant in our environment.

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#78

Post by account42 »

ahartmetz wrote: post #66
0x1ceb00da wrote: post #63

Earlier quoted context omitted.

> as many games did 10-15 years ago Examples?

I didn't play much at the time because of the lack of games on Linux, but I've played some Far Cry 3 (from 2012) recently where I did turn down SSAO in the settings.

Amnesia: The Dark Descent is the example that always comes to mind for me (2010, also available on Linux at the time).

https://www.youtube.com/watch?v=vBZ7NEyPUDw

https://frictionalgames.com/2014-01-tech-feature-ssao-and-te...

Re: Corners Don't Look Like That: Regarding Screenspace Ambient Occlusion (2012)

#79

Post by nunodonato »

Geee wrote: post #30
overgard wrote: post #7

I agree with his overall point, but I would point out: realism is not usually the point, the point is to look good. The problem with realism is once you get past "wow the computer can do that now", it's not very interesting -- most of reality is pretty dull looking!

I don't think this is true at all. I've been experimenting with a physical sky / atmosphere modeling, and it really seems that the most physically accurate sky is the most beautiful. I think this applies more generally to all light and shadows, and all natural effects which people perceive as beautiful, and at the same time difficult / expensive to recreate on a computer.

Not to disagree with you, but I've noticed that many people have very little clue about what nature looks like. I see that in CGI/games a lot, trees, clouds, atmosphere, grass, moon... totally wrong from what actually happens in the world. But it looks good! :D
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