It’s called Illusionistic ceiling painting,
which includes the techniques of perspective di sotto in sù and quadratura, is the tradition in Renaissance, Baroque and Rococo art in which trompe l'oeil, perspective tools such as foreshortening, and other spatial effects are used to create the illusion of three-dimensional space on an otherwise two-dimensional or mostly flat ceiling surface above the viewer. It is frequently used to visually suggest an open sky, such as with the oculus in Andrea Mantegna's Camera degli Sposi, or a fictive architectural space such as in the illusionistic cupola, one of Andrea Pozzo's frescoes in Sant'Ignazio, Rome.