[bsenftner]

Only one photo is needed. I've not looked deep into this specific project, but speaking as an early developer of likeness transfer trained algorithms, only one image is needed, and it can even be a crude sketch - but if one's true likeness is captured by an image it can be recreated in full 3D. The catch is an individual's specific facial expressions, such as the real individual has a slightly lopsided smile, or they have smile dimples, or simply their characteristic at rest facial positions are absent, so they don't look like themselves to those that know them.