 Convex Triangular Subdivision Surfaces with Bounded Curvature by Charles Loop

Primary text: www.microsoft.com/en-us/research/wp-content/uploads/2016/02/tr-2000-71.pdf

Cited passages: section 2, Loop's algorithm and original masks; sections 3–4, especially Remark 1, original central weight alpha, lambda0=5/8 and lambda1=3/8+(1/4)cos(2pi/n); introduction, regular and extraordinary vertices.