Design Nomenclature / Form & Geometry
Sphere
Also called uv sphere, icosphere, ellipsoid, ball
This entry has not been translated yet and is shown in English.
The set of points equidistant from a center — the only closed surface with constant positive Gaussian curvature. An ellipsoid is a sphere scaled unequally along its axes and is no longer constant-curvature. No mesh represents either exactly: a UV sphere approximates it with latitude rings and two poles, an icosphere by subdividing an icosahedron into near-uniform faces.
In practice
Choosing between them is a topology decision, not a shape one. UV spheres unwrap cleanly and pinch when deformed; icospheres deform evenly, unwrap badly, and hide twelve five-valence poles instead of two bad ones.