Some of Leonardo drawings show the "sfumato" technique to render realistic effects. It is in this period that Giotto's realism lessons ( and also Cavallini's, , Duccio's and Masaccio's ) are enhanced to even more spectacular levels.
Leonardo da Vinci, Study of Arms and Hands. c. 1474.
Pen and Ink with white chalk on brown paper
Leonardo, cartoon, national gallery (c. 1499-1500)
Head of a Young Woman , Accademia di Belle Arti, Venice
Head of the Vergin, 1508-1512, MET New York
The Chiaroscuro is a technique which manipulates the shades. It was known in the ancient Greece (Apollodoro, Polignoto of Thasos).
Leonardo modified it in a "sfumato" technique which renders the passing from light to dark softer.