There is a twelve and a half minute TED Talk by Hany Farid that was given in Vancouver on April 10, 2025 and posted at YouTube on July 18, 2025. It is titled How to Spot Fake AI Photos | Hany Farid | TED. He discusses using vanishing points and shadows:
“If you image parallel lines in the physical world they will converge to a single point, what’s called the vanishing point.”
“Surprisingly shadows have a lot in common with vanishing points. Here what I’ve done is I’ve annotated a point on the shadow with the corresponding part on the bottom of the rail that is casting that shadow, and I’ve extended those lines outward. And they intersect, not at a vanishing point, but at the light that is casting that shadow.”
There also is a ten-page article by Hany Farid at PNAS Nexus on July 29, 2025 titled Mitigating the harms of manipulated media: Confronting deepfakes and digital deception. Reference #35 from that article is a 13-page pdf preprint titled Perspective (In)Consistency of Paint by Text which discusses vanishing points, shadows, and reflections.
A multiple-exposure spirit photograph from 1901 by S. W. Fallis with a portrait of John K. Hallowell and super-imposed faces of fifteen deceased people including George Washington and Queen Victoria came from Wikimedia Commons.
