TL;DR: A virtual try on glasses demo is a best-case recording. I run seven checks on a live camera before I believe one: real-world scale, temple occlusion, head turns, lens rendering, jitter, bad light, and how a frame gets into the catalog. This post is a checklist. I have not published measurements here. I look at a lot of virtual try on glasses demos for client projects. Most of them look fine in the first ten seconds, because the demo is a frontal face, good light and one hand-tuned frame.
