Filtering is a method of antialiasing the bitmaps in mapped materials by averaging pixels. The Pyramidal and Summed Area options provide two methods of pixel averaging. Only one can be active at a time.
Both methods require approximately the same rendering time. Summed-area filtering generally yields superior results but requires much more memory. Pyramidal filtering requires 3ds Max to allocate memory equal to approximately 133% of the size of the bitmap. By comparison, summed-area filtering requires 3ds Max to allocate approximately 400% of the size of the bitmap.
Use summed-area filtering only for smaller bitmaps, and avoid using any more such bitmaps in a scene than necessary.
Pyramidal filtering is adequate for most purposes. However, because it applies filtering as a function of distance, irregular antialiasing might occur on detailed texture maps that are applied to a plane receding into the distance. The effect of pyramidal filtering on extreme perspectives such as this is even more noticeable in animations, where portions of the texture map appear to "swim." If this occurs, choose the summed-area filtering method for the material.
Preferences Rendering and toggle Filter Background in the Background group.