 Later versions of the text, like Ignazio Danti's 1573 annotated translation, would add a description of the camera obscura principle to demonstrate Euclid's ideas.In the 6th century, the Byzantine-Greek mathematician and architect Anthemius of Tralles (most famous as a co-architect of the Hagia Sophia), experimented with effects related to the camera obscura.Anthemius had a sophisticated understanding of the involved optics, as demonstrated by a light-ray diagram he constructed in 555 CE.