Post news Report content RSS feed [w]tech - Antialiasing and Ambient Occlusion

First news pack of two which are about post processing of [w]tech. Get short overview and see what they are good for.

Posted by unrealer2 on Jul 17th, 2011

("Screen Space AntiAliasing")

Supporting AnitAliasing has become a serious problem for game-developers in the last years. Most of them use some kind of Deferred Rendering now, which does not support Hardware-AntiAliasing. But since everyone likes to have antialiased scenes in games anywas, developers have to come up with some little tricks.
For [w]tech we're using a post-processing effect which we call simply "Screen Space AntiAliasing":

Screen Space AntiAliasing

This effect is very low-costly, and we’re quite happy with the results. Though, it looks best on round things.

("Horizon Based Ambient Occlusion")

Another new PostProcessing-Effect in [w]tech is “Horizon Based Ambient Occlusion”, which was originally invented by Nvidia.The results are very pleasing for a screenspace approach of AmbientOcclusion. Of course those will never be as accurate as the non-screenspace versions, but those can’t be handled pretty well in realtime on current hardware.
Here are some pictures of the HBAO-Effect, rendered at a resolution of 800x600 on ATI Radeon 4890:


A little animation which should give you an impression how HBAO can improve the illusion of reality:

As SSAOs always are, this effect isn’t lightweight. Luckily a drop from 300 to 140 FPS isn't that bad, since FPS are non-linear. A drop from 30 to 20 would be much worse!

Bermuda - Generator

For more information, visit:

Post comment Comments
Jokerme Jul 18 2011 says:

Ambient Occlusion is on the best atmospheric effects out there. It creates wonders if you ask me. Pity it's such a costly effect.

+3 votes     reply to comment
Kamikazi[Uk] Jul 18 2011 says:

I have always been a fan of ambient occlusion rendering but i feel it's always a big performance hit and generally i always turn it off as you get 20 fps+ most of time.

+1 vote     reply to comment
Metalspy Jul 18 2011 replied:

That's why there are high-end graphics cards on the market ;) Of course I udnerstand that not everyone can or wants to spend that much money on a graphics card. But yeah, AO is great, I love how it generally adds a lot to scenes.

0 votes     reply to comment
cryora Jul 18 2011 says:

I'm not sure what it does besides adding blobbish shadow effects where two surfaces are at close proximity to each other. While in some situations it makes the image look more realistic, in other situations it creates excessive darkness where darkness doesn't belong.

+1 vote     reply to comment
Kamikazi[Uk] Jul 18 2011 replied:

It adds shadows on edges of everything. It gives the scene more definition which generally makes it look better, it can sometimes back fire though and then everything looks dark and blurry.

+1 vote     reply to comment
[WuTz]! Jul 18 2011 replied:

That's what AmbientOcclusion is supposed to do. It simulates the light coming from the sky, which comes from almost all sides in the world.
Imagine you see some car on the street. There will be a very soft shadow underneath it because it blocks the light from the sky. Just using a shadow-casting light won't do the trick to get that shadow. It would be too hard and would feel unrealistic.

Sure, no screen-space approach can get even close to the real ambient occlusion, but current hardware isn't really capable to compute that in realtime (Well, it works, but it isn't really fast). So you're right, it will create shadows where a shadow doesn't belong to sometimes. One of the problems you have with SSAO.

+1 vote     reply to comment
RedTailTeam Jul 18 2011 says:


+1 vote     reply to comment
Post a comment

You are not logged in, your comment will be anonymous unless you join the community. Or sign in with your social account:

Post news
Related Engines
[w]tech Creative Commons TBD
Related Groups
[w]tech team
[w]tech team Developer with 3 members