Which filtering method provides the best texture quality at oblique viewing angles?

• A. Nearest: uses the closest texel with no interpolation.
• B. Bilinear: blends between four texels.
• C. Trilinear: interpolates across mipmap levels.
• D. Anisotropic filtering improves quality at oblique viewing angles.

Answer: (D)

When a surface is viewed obliquely, its texture footprint on the screen stretches along a particular direction. Nearest sampling grabs just a single texel, which creates blocky, pixelated appearances. Bilinear blends four nearby texels in the same level, smoothing a bit but still blurring along the stretched direction. Trilinear further smooths by mixing between mipmap levels, which helps with aliasing during minification but doesn’t adapt to the directional elongation of the footprint. Anisotropic filtering addresses this by sampling along the major axis of the texture’s footprint, using more texels where the stretch is long. This preserves detail and reduces blur when textures are viewed at sharp angles, making it the best option for texture quality at oblique viewing angles.