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Thursday, 23 December 2010

Anti aliasing

I've wanted to implement  some form of anti aliasing for a while now so I took a break from playing through the recent Humble Indie Bundle and looked into it. There are several different options when it comes to AA in deferred rendering so I've started with what seemed to be the easiest. The method I've used here is the one outlined in GPU Gems: Deferred Shading in Tabula Rasa and I haven't really deviated from that article with regards to AA.

I also took the opportunity to look into applying a post process sharpen to the overall image. The method is known as unsharp masking and it's an effect a lot of digital artists use to spruce up their images. It goes back further actually and I was surprised to learn that the technique was pioneered in conventional photographic darkrooms.

You can see some examples of AA and unsharp masking below. Be sure to view them full screen without any scaling as the difference is hard to spot when the images are down sampled. In some areas the sharpen effect over sharpens fine details and increases the aliasing problem although for the most part the effect is an improvement.






















Fullscreen examples (click for larger versions)


With AA
No AA


With AA

No AA




With AA
No AA


Well that was fun, back to playing Cortex Command... sniping the engines off drop ships never get's boring ;)

5 comments:

Vrav said...

I know it's really just an issue of style, but I feel like sharpening at half this would look a lot better. Or something, I don't know, 60-70%. Guessing you just turned it up to make the effect more apparent. Shots are looking nice, in any case!

Stefan Kamoda said...

The effect is a little too strong in these shots. I think it's a case of 'just implemented an effect'-itis. It's sort of like SSAO in that it works best when you can barely see it, at which point the temptation is to crank it up because you can barely see it :)

Vrav said...

Haha, yeah. Totally know what you mean. (:

jarkko said...

If your still interested in improving AA quality I would recommend on reading about SRAA.
http://research.nvidia.com/publication/subpixel-reconstruction-antialiasing

Stefan Kamoda said...

Thanks for the tip Jarkko.That looks like a great technique :)

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