Interestingly, Leonardo may have experimented with binocular vs. monocular perspective for at least one alternative version of his _Mona Lisa_:

https://monalisa.org/2013/12/15/genius-leonardo-da-vinci-per...

which makes one wonder if there are instances of his having used other perspectives in his drawings (cabinet for drawings for furniture for his home or workshop for a cabinetmaker, or cavalier for a map/diagram for military planning), and wish that the entirety of his oeuvre were available in a digital format like to the Corbis CD-ROM Leonardo's rendering of the Codex Leceister:

https://archive.nytimes.com/www.nytimes.com/library/cyber/mi...