Anti_Aliasing, MSAA, OSAA, others..
Author
I'm trying to see my options here. I'm mainly going to either OSAA and render to an FBO that is 2x the screen size or:
MSAA. MSAA seems fast and it just requires a buffer the size of the screen, but I'm looking for results. Does anyone know of a document that shows 2 images: 1 non-AA, and one MSAA?
Other ways you know of?
I guess, from your description, with OSAA you mean FSAA (FullScreenAntiAliasing)?
MSAA is doing the same, having internally a twice as big framebuffer, the difference is that shading is not done for every sub-pixel, but just once and just the rasterization (zbuffer-depth and triangle-shapes) are checked on subpixel basis.
subpixel are usually close together, you barely see a difference between MSAA and FSAA, and IF you really do, you either
- have texture aliasing that can be tackled with mipmaps and/or Anisotropic filtering
- have shader aliasing and in that case, having twice or quad the subpixelcount will just slightly improve the issue until you go to crazy, 16+ AA settings.
MSAA is doing the same, having internally a twice as big framebuffer, the difference is that shading is not done for every sub-pixel, but just once and just the rasterization (zbuffer-depth and triangle-shapes) are checked on subpixel basis.
subpixel are usually close together, you barely see a difference between MSAA and FSAA, and IF you really do, you either
- have texture aliasing that can be tackled with mipmaps and/or Anisotropic filtering
- have shader aliasing and in that case, having twice or quad the subpixelcount will just slightly improve the issue until you go to crazy, 16+ AA settings.
The term you're actually looking for is "SSAA", or "Super Sampled Anti Aliasing". MSAA and SSAA are a subset of FSAA. In SSAA, every pixel of the screen is sampled more than once - this means a double requirement of fillrate, bandwidth, and such.
MSAA only applies to polygon edges, which achieves mostly the same thing but at a much lower cost than SSAA. For the same performance cost, MSAA typically looks better - you might be able to do 4x or even 8x MSAA for the same performance cost as 2x SSAA. However there are some things that MSAA can't deal with, for example texture and shader aliasing.
If performance isn't a concern, SSAA will produce better results overall.
MSAA only applies to polygon edges, which achieves mostly the same thing but at a much lower cost than SSAA. For the same performance cost, MSAA typically looks better - you might be able to do 4x or even 8x MSAA for the same performance cost as 2x SSAA. However there are some things that MSAA can't deal with, for example texture and shader aliasing.
If performance isn't a concern, SSAA will produce better results overall.
Super-sampling *usually* isn't a practical option. A 2X increase in resolution usually puts a lot more pressure on the GPU. Plus remember that as far as geometry edges are concerned, they won't look any better than they would look with 2x MSAA.
The only other option in use is depth-based post processing to try to smooth edges. This is usually done by using an edge-detect filter to detect polygon edges, and then using the results of that to control how much the pixel is blurred. Crysis does this when you have MSAA turned off.
The only other option in use is depth-based post processing to try to smooth edges. This is usually done by using an edge-detect filter to detect polygon edges, and then using the results of that to control how much the pixel is blurred. Crysis does this when you have MSAA turned off.
Author
Thanks, Yea I just love seeing super-sampling when I render in Blender. And I want really nice "soft" images, but I don't think I will be able to render at double resolution. I mean there are lots of amazing games like crysis, but that "softness" of super-sampling I think is just amazing in feel.
Oh here, meant to post this before but I forgot:
http://www.tweakguides.com/images/Antialiasing.gif.
It shows a scene with no MSAA, and then with 4xMSAA.
http://www.tweakguides.com/images/Antialiasing.gif.
It shows a scene with no MSAA, and then with 4xMSAA.
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