Getting confused about Ambient Occlusio

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5 comments, last by MJP 12 years, 4 months ago
Hey!

I would like to play a bit with Ambient Occlusion but i'm in trouble since there are a lot of implementations and even googling i was not able to have a clear idea about this technique.

For now i've found:
ScreenSpace Ambient Occlusion
Horizon Based Ambient Occlusion
High Definition Ambient Occlusion


There is also a tutorial on gamedev about ambient occlusion, i can't make a clear idea and understand differences.

May someone give me some hints?
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These are all just various techniques to achieve screen space ambient occlusion--just like there are many algorithms to achieve shadow mapping. Each of them have their strengths and weaknesses. I would encourage you to do some research yourself into which method you find the most attractive. If you're just learning, try a simpler approach before tackling the more improved versions. I know nVidia has some good papers on SSAO.

Good luck!
Screen-Space Ambient Occlusion seems to be the preferred choice for most developers, probably because it's straightforward to apply to existing rendering frameworks, and it is not at the mercy of the geometric complexity of the scene. Hence, why it's done in screen space and not world space. The prerequisites are that you need at least a depth map, and usually a normal map, which is available through deferred rendering.

Out of all the examples I have found, this article has the easiest to understand explanation and tutorial I have read about SSAO. It briefly covers the "Crysis approach" which is the pioneer of the SSAO technique, and then explains a modified version of that for better looking ambient occlusion maps.
Electronic Meteor - My experiences with XNA and game development
Thank you for the link!
All screen-space techniques have the same primary advantages and weaknesses. The main advantage is that it "just works" for all static/dynamic geometry, and can be mostly-orthogonal to how you do your rendering + lighting. The main disadvantage is that you have little information to work with using just a depth buffer, which makes it difficult or impossible to simulate a lot of occlusion (particularly large-scale occlusion).
Thank you, now i have a little bit cleaner idea.

P.S: Congrats for the book, i've purchased it and waiting!
Thanks! I hope that you find it useful.

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