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Faking SSAO
http://horde3d.org/forums/viewtopic.php?f=7&t=220		 Page 1 of 1
Author:  swiftcoder [ 16.01.2008, 14:32 ]
Post subject:  Faking SSAO
So I am having some fun trying to fake some SSAO using only the depth buffer (as described in the Journal of Ysaneya). As is to be expected, my results so far are somewhat less than I would have desired :?

Here is a (very preliminary) screenshot of just the AO term that is to be multiplied with the scene - At the moment it looks more like an edge-blur than an AO term, but with time:
larger image
Image

Currently I take the depth buffer, take the absolute difference of a pixel's depth and its neighbours, and use that factor to set the radius of 12-sample Poisson disk blur, multiplying the sample distance by the radius, and running 2 passes. This is giving fairly decent results, with out a huge performance hit, but I think a better blur might be possible, so if anyone has suggestions on that, they would be most welcome...

Also, I really need a more complex scene to test with this - but I am no artist :)
If anyone has an indoor scene I could borrow for these tests, I would be overjoyed!
Author:  marciano [ 16.01.2008, 14:58 ]
Post subject: 
Nice to see that you are working on that!
In fact the results resemble an edge detection filter at the moment but this doesn't necessarily have to be wrong since the model is relatively convex and so you wouldn't have much ambient occlusion.

For my quick SSAO test I have created a simple but useful test scene with several boxes lying on a heap. If you want I can send you the scene and also my SSAO shader version.
Author:  swiftcoder [ 16.01.2008, 18:59 ]
Post subject: 
marciano wrote:
For my quick SSAO test I have created a simple but useful test scene with several boxes lying on a heap. If you want I can send you the scene and also my SSAO shader version.

The scene would be very handy — I haven't quite got the kinks out of my Blender -> Collada -> Horde workflow yet :) — and it wouldn't hurt to compare shader approaches, especially since I am fairly new to all this.

Do you want to email it to me? swiftcoder@gmail.com
Author:  Mikmacer [ 22.08.2008, 05:28 ]
Post subject:  Re: Faking SSAO
Ive been working on a SSAO with horde3D!

Its a "work in progress" and I'm currently trying different idea about how to realise it:


Some images rendered with the Deferred lighting:
1) With SSAO
2) Without SSAO
3) Occlusion
Image
Author:  Volker [ 22.08.2008, 06:52 ]
Post subject:  Re: Faking SSAO
Impressive!
Author:  marciano [ 26.08.2008, 20:15 ]
Post subject:  Re: Faking SSAO
Great! Personally I love ssao for its simple idea, although it is still very tough to make it look really good.

From time to time I'm also experimenting a bit with my implementation. I really hope that we will get a nice reference implementation for Horde through a joint community effort.
Author:  DarkAngel [ 27.08.2008, 02:19 ]
Post subject:  Re: Faking SSAO
The Advances in Real-Time Rendering in 3D Graphics and Games paper has some good SSAO tips from blizzard in it - might be worth a look over ;)
Author:  Mikmacer [ 27.08.2008, 02:57 ]
Post subject:  Re: Faking SSAO
The article about SSAO in SC 2 is really good since Ive already used a lot of their tips in my work about SSAO. Since the picture in my previous post, Ive been working a lot and Ive got a better result now. Ive been able to deal with self-occlusion, but Ive got an another problem at this time. I'm working on it, and I expect to get something really great one day! :p

A screenshot from my early SSAO ( with some self-occlusion issues ):

Image
Author:  zoombapup [ 04.07.2009, 18:18 ]
Post subject:  Re: Faking SSAO
Have a look for a slight improvement on SSAO, called screen space directional occlusion. Its a really neat little idea and builds on SSAO code pretty simply. Plus its not a whole lot more work (perhaps 3% time, without the additional light bounce). It adds directionality to the occlusion so you get a bit more "shadow" in your occlusion shadows. Plus it can produce light bleed where one object bounces coloured light to another object.
Author:  Orm [ 26.09.2009, 23:59 ]
Post subject:  Re: Faking SSAO
Incredible work, although I can see in a game situation the performance hit would be game breaking... if Crys's implimentation is any indication. :lol:
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