User's Manual

User Guide for Chrome 400 Series Graphics
SG192-C.1 10/17/2008
Page 121
more MIP maps to better approximate very distorted
textures. Anisotropic can be used in conjunction with
bilinear or trilinear filtering as well as MIP map filtering.
While trilinear filtering is capable of producing fine
visuals, it only samples from a square area, which is not
the ideal sampling area for all cases. Anisotropic filtering
averages sixteen texture samples, or taps, in a non-
square, rectangular or parallelogram shaped texture
sampling pattern whose length varies in proportion to the
orientation of the stretch effect. This sampling rate is four
times the sampling level of bilinear filtering and twice the
sampling level of trilinear filtering.
Textures applied to a sloped surface will not look fuzzy,
which is especially useful when rendering shapes with a
high degree of surface tilting in the X-Y-Z planes. Full
use of the anisotropic filtering capabilities may impact
performance.
Setting options include:
By App (default) – Select By App if you want S3
Graphics software to use the anisotropic filtering
level requested by the application. Not all
applications request anisotropic filtering, and S3
Graphics software does not perform anisotropic
filtering unless requested. This is the default.
OFF – Select OFF to force anisotropic filtering to be
always off.
2X – Select 2X to enable anisotropic filtering at its
lowest level. With this setting, 16 texture samples
(taps) selected from a non-square pattern will be
averaged to generate one texture element (texel)
that is then applied to a single pixel.
3X, 4X, …, 15X – Select intermediate sampling
levels to match your preferred balance between
quality and performance. The higher the sampling
level, the greater the degree of filtering. Visual
quality will improve at the expense of performance.
16X – Select 16X to force use of classic anisotropic
sampling using 128 taps in a non-square sampling
pattern. This level of filtering will produce very high
quality visual output, usually with a decrease in
rendering speed.