An official website of the United States government
Here's how you know
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Initial mesh with eight crease edges and a crease vertex (a), results after bi-linear sub-division (b), and centroid averaging (c), and after 2 (d), 3 (e) and 4 (f) subdivision iterations, respectively.