ATI was the first 3d hardware vendor to introduce some anisotropic filtering optimizations- some would say shortcuts- in their cards which allowed much higher performance. And the performance penalty increases with resolution. Proper anisotropic filtering is computationally expensive, even on dedicated 3D hardware. These are detail elements cropped from the full-size 1024x768 screenshots: standard, anisotropic. Here are some screenshots I took from the PC game FlatOut which illustrate the dramatic difference between standard filtering and anisotropic filtering: And that's what anisotropic filtering does:īecause you're typically viewing most of the polygons in the world at an angle at any given time, anisotropic filtering has a profound impact on image quality. Much more detail should be retained into the distance. The problem with simple mip-mapping and bilinear filtering is that they're too simple. if we didn't mip-map into the distance, the image would look extremely noisy: Now, some detail loss with distance is intentional. As you rotate a texture-mapped polygon away from the viewer, simple bilinear filtering and mip-mapping cause the texture to lose detail as the angle increases: But I do want to highlight one particular peculiarity of bitmap scaling in 3D graphics. This is done via bilinear filtering.Ī full discussion of 3D graphics is way outside the scope of this post- plus I don't want to bore you to death with concepts like trilinear filtering and mip-mapping. When a texture is applied to a polygon, the texture may be scaled up or down to fit, depending on your screen resolution. Bicubic filtering before in the context of 2D images, but bilinear filtering is a key ingredient in 3D graphics, too.
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