Design Nomenclature / Form & Geometry
G1 continuity
Also called tangent continuity, tangency, g0 continuity, positional continuity
This entry has not been translated yet and is shown in English.
Two curves or surfaces meet G1 when they share a point and a tangent direction there, but not necessarily curvature. The join reads as smooth in outline and in a matte render, and shows a hard kink under a specular highlight or a zebra stripe, because the reflected direction jumps. G0 below it is contact only: position, no shared tangent.
In practice
'Tangent' is the CAD word and the default a fillet gives you. Enough for a machined bracket, not enough for a Class-A surface, where a tangent-only join reads as a crease the moment a strip light crosses it.