Geek Corner: Ansiotropic Filtering for the Masses

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Date: Thursday, November 7th, 2002, 01:55
Category: Archive

An Archive reader posted this to comments yesterday — everything you wanted to know about ansiotropic filtering but were afraid to ask! Thanks, Archive and Extremetech! This should save us from Jon Rubinstein explaining the concept at the next keynote! -PK

Extremetech sez: “Anisotropic filtering (AF) is used to address a specific kind of texture artifact that occurs when a 3D surface is sloped relative to the view camera. Before we drill too deeply, here’s a working definition of the word itself. Isotropy describes when an object’s vectors are of equal value along its different axes, like a square or a cube. For instance, bilinear and trilinear filtering are both isotropic filtering techniques, since their filtering pattern is square. Anisotropic filtering occurs when the filtering pattern exhibits different values along different axes. AF uses a non-square, or an-isotropic filtering pattern, hence the name. The pattern used by AF is typically rectangular, though it can at times be trapezoidal or parallelogram-shaped.” Examples and more here:,3973,559035,00.asp

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