Sphere Mapping

Uniform Sphere Mapping

Uniform sphere mapping textures a sphere linearly in both longitude and latitude directions.

Mercator Style Sphere Mapping  

Mercator sphere mapping non-uniformly maps latitude to apply more texture resolution toward the poles.  Style is more conformal to a spherical shape and reduces distortion that occurs at the poles with uniform sphere mapping.  Mercator style is commonly used for earth globe maps.

Note: A modified Mercator mapping known as Miller-Mercator is used to better maintain map scale around the equator area.

Left: Uniform mapping, Right: Mercator style mapping

Triplanar Sphere Mapping

Triplanar mapping uses both vertex position and normal vector to choose a planar texture projection that matches primary surface direction.  Triplanar mapping is able to render appearance of a continuously mapped sphere without any distortion at poles. 

Note: Mapping style is best used with textures that do not have a definable tile pattern.

Triplanar mapping using a rock style texture

Triplanar mapping using a brick style texture, due to tile pattern change in texture direction is evident between central and pole regions of sphere