By Leonardo’s time, artist’s perspective had become an established tool in Florentine workshops. This was a system that created the illusion of space based on the principle that the scale of all elements in a painting was governed by their position in space.

The Annunciation indicates that Leonardo clearly knew about artist’s perspective by the early 1470s. The tiled floor pattern on the right is diagonally orientated, indicating that the lateral point system has been applied. This was based on two vanishing points placed on the horizon line, and had long been in use by Florentine artists (one roughly where the distant town is seen and the other on the upper right edge of the picture). 

Leonardo’s perspective has a distorting effect due to the sudden transition from near to distant space. He wanted to make the figures as large as possible, (the Virgin’s palace is huge), while simultaneously including a panoramic view into the landscape. As such, the painting can be seen as the product of the ambitions of a young artist, albeit one who was still learning the subtleties of his craft.

In Leonardo's words
Perspective is nothing else than the seeing of an object behind a sheet of glass…these things approach the point of the eye in pyramids, and these pyramids are cut by the said glass.