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  1. #1
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    Ambient Occlusion in Real Life - Lighting Question

    Hey people. I wanted to do some short tutorials for a beginners forum I frequent and one is going to be about ambient occlusion.

    The problem is that ambient occlusion is a 3d term, even though the effect can be seen in real life as well (for example, in the corners of a room), and I'm aiming the tutorial more at 2d artists. I was wondering what the real life term for that kind of light effect is. Diffuse reflection has been mentioned, but I don't think that encompasses AO's effect fully.

    Any of you magnificent bastards know what it's called?

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  3. #2
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    What!? There's no such thing. Ambient Occlusion only exists in the video game world to cover the inadequate power of a system to display lots of polygons.

    Actually, I don't know. Wouldn't it be similar to atmospheric perspective?

  4. #3
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    Are you talking about reflected light? I don't know what else needs to be covered beyond direct light, reflected light, and ambient light.
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  5. #4
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    With ambient occlusion, you'll get something like this:
    Ambient Occlusion in Real Life - Lighting Question
    where there are soft shadows in the corners.

    You can see the same shadow type in real life in many places and I want to know if that type of shadow effect has a particular name, or if it's just a shadow without any formal description. It would be cool if there was a description for that effect because then I could do some research and see exactly why it happens.

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  7. #6
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    How about if you think about it not as a shadow effect, but as a lack of reflected light?

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    hey dfacto this going on BBS? good memories

    ok ive only just started studying lighting but i thought that the soft shadow effect that is shown in ur picture was the result of reflected light on the normal 1 2 3 values , so if u like the the darker part of the shadows is in fact the orginal 1 2 3 values and the reason they fade and soften is because they blend into the reflected light, whether theres a special name for that however, i dunno.

    just a students understanding though, and could be wrong,

  9. #8
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    The cause is a mixture of the interference caused by a light wave meeting a reflected lightwave (which is now at a different wavelength), and that almost all light coming out of a corner to the viewer is atleast a double reflection, the tighter into the corner you go the more light gets reflected away.

    This is only my understanding of the physics from about seven years ago.

  10. #9
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    I think it's a little too fine detail to be mentioning on a tut for beginers to be honest. The subtleties of bounced light in corners isn't really in the basics of light and shadow is it?
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  11. #10
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    I think the word "occlusion" by itself would cover the phenomenon, but it isn't something that I've often seen mentioned except for its extreme form, the "crevice shadow". Maybe it should be pointed out more often.

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    Isn't it just a collection of diffuse shadows cast from multiple lightsources (i.e. ambience).

    As for (indoor) corners being dark, it may also be because they're further from the lightsource(s) in general.

    I can also imagine some corners actually becoming brighter because of reflected light (i.e. a boob clevage with light bouncing back and forth, lighting the shadows up aswell as saturating them).
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  13. #12
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    I've never seen this occure in real life, unless i am looking at photographs from an electron microscope. I don't believe natural light in real space (ie, from human perspective) actually makes those sort of shadows. At least, i've never seen it.
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    Bounce light?

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    Basically if you view a object on an overcast day it happens in real life, where the light is bounced from numerous sources in absence of a strong light source like a sunlight or bulb.

    A 3d term is global illumination where instead of the computer calculating the path of light cast (ray tracing) the computer calculates all the angles of light bounced off surrounding objects, which can take much longer to render as a result.

    You can emulate this effect in realtime for games. Think Mario Galaxy and a few others.

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    Quote Originally Posted by Blue
    I've never seen this occure in real life, unless i am looking at photographs from an electron microscope. I don't believe natural light in real space (ie, from human perspective) actually makes those sort of shadows. At least, i've never seen it.
    You've never been a room with corners?
    Seriously, look around. There's all sorts of stuff going on that you've never seen, because you didn't know to look.

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