For his Roman Emperor Project, Daniel Voshart (whose day job includes making VR sets for Star Trek: Discovery) used a neural-net tool and images of 800 sculptures to create photorealistic portraits of every Roman emperor from 27 BCE to 285 ACE. From the introduction to the project:
Artistic interpretations are, by their nature, more art than science but I’ve made an effort to cross-reference their appearance (hair, eyes, ethnicity etc.) to historical texts and coinage. I’ve striven to age them according to the year of death — their appearance prior to any major illness.
My goal was not to romanticize emperors or make them seem heroic. In choosing bust / sculptures, my approach was to favor the bust that was made when the emperor was alive. Otherwise, I favored the bust made with the greatest craftsmanship and where the emperor was stereotypically uglier — my pet theory being that artists were likely trying to flatter their subjects.
Some emperors (latter dynasties, short reigns) did not have surviving busts. For this, I researched multiple coin depictions, family tree and birthplaces. Sometimes I created my own composites.