Textures, textures, textures.

posted in Cypher's Journal
Published February 01, 2006
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Well, first off, the introduction to aniso filtering that I promised Yemen. In the past graphics only had textures that were filtered with just nearest point magnification (many pixels for one texel) and minification (many texels for one pixel). For magnification, we can now simply do linear filtering, which smooths out the textures, and makes it look less chunky. For minification we need to use mipmaps (smaller versions of the base texture) to choose when we're going to be using a specific texture. The idea behind mipmaps is that since we could have, say, a 256x256 texture dumped on a pixel-sized triangle, and the average of all of those texels would have to be found. Since that's beyond impractical for realtime use, a mipmap chain is created, full of smaller and smaller versions of that texture, all the way down to a 1x1 texture (which, in the case suggested above, is the one that is sampeld). By linearly filtering across the mipmap chain, transitions between mipmaps can be quite smooth, and greatly helps reduce shimmering artifacts due to bad minification sampling. Aniso filtering I don't know the exact details, but the end result, bascally, is that the highest possible mipmap is chosen for any pixel. This is determined (again, basically) by the angle of the triangle in relaiton to the camera and the distance of the triangle from the camera, whereas simply doing a linear filter between mipmaps seems to only use distance from the camera to determine what mipmap to use. The result of aniso filtering is that textures end up looking very crisp and aliasing free when minified, which is a far cry compared to point filtering:

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(point filtering is on the left, aniso is on the right. This was a 2048x2048 texture rendered to a 300x300 display)

Anyways, now that that's out of the way, I've decided to abandon RFBTexture (in its current form) for awhile, as something far more interesting has caught my attention. I'm not going to talk about now or for awhile, as I would like to surprise my peers [smile].
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0 likes 2 comments

Comments

jollyjeffers
Quote:I'm not going to talk about now or for awhile, as I would like to surprise my peers

*stamps feet*

I want to know now!

Jack
February 01, 2006 11:11 AM
MustEatYemen
Sorry for the delay in me getting to your article :D

Cool, now I understand, thanks alot :)
February 02, 2006 02:55 PM
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