Design Nomenclature / Form & Geometry
Topology
Also called edge flow, mesh topology
In mathematics, the properties of a shape preserved under continuous deformation: a mug and a torus are the same object, and every quad mesh of a sphere has genus zero however its edges run. In modeling, the word means something else entirely — the quality and direction of edge flow across a surface.
In practice
Both senses are current and neither is wrong. 'Bad topology' on a forum never means the genus is wrong; it means the loops fight the form or the deformation. Say 'edge flow' when edge flow is what you mean.
Not to be confused with
- GenusThe number of handles on a closed orientable surface — holes you could thread a string through, not dents or openings. A sphere is genus 0, a torus 1, a two-handled cup 2. Euler's formula fixes it exactly: V − E + F = 2 − 2g, regardless of how dense the mesh is or how its edges run.
- Edge loopA path of edges that continues straight through every four-valence vertex it meets, turning neither left nor right, and usually closing on itself. Loops run along the surface's structural direction and terminate at poles, boundaries, and n-gons. They are the unit of insertion: adding one adds an entire band of geometry at once.