"Stuff like this is hard to validate. For most renaissance artists, their self-portraits are far from photorealistic."

Author here. Agreed, it's definitely not a science.

I suspect the author of this article I link to in the post might disagree though: http://www.laboratoiredanthropologieanatomiqueetdepaleopatho.... He is making an actual claim to scientific validity, complete with tables of measurements of the distance between Benvenuto Cellini's "lateral nasal point" and pupils in various potential self-portraits. I'm skeptical, but it's interesting to note that the author seems to know what he's talking about (director of a university paleopathalogy lab and "Expert en Anthropologie d'identification" for the French legal system).