Final answer:
Chiaroscuro is the method used to create the illusion of a three-dimensional form on a two-dimensional surface by applying contrasts of light and shadow.
Step-by-step explanation:
The method of applying value to a 2-D work in order to create the illusion of a 3-D form is called chiaroscuro. This artistic technique, which was developed during the Renaissance era, involves the use of light and dark contrasts to give a sense of depth or volume in two-dimensional work. Chiaroscuro plays with shadows and highlights to simulate three-dimensionality on a flat surface, making the subject appear more lifelike and three-dimensional. Artists like Raphael employed this method in works such as La Donna Velata to convey a realistic depiction of the human form.