Focus on this artwork and analyze the Visual analysis.
In this piece there are three angels with wings who have come to meet with Mary. Gabriel is in front of two other angels kneeling while they stand. He is holding a lily which is symbol of purity. The dove flying above is a symbol of holy spirit.
The other two angels are looking off into the distance and not at Mary. The one closest to the audience is looking directly at us, as if acknowledging our presence. They wear woven red socks which are a similar color to their outer garments. Under this red drape they wear light grey outfits tied around their waists by a rope. Mary is wearing a darker grey garment with gold outlining and a light-colored headwear. She is looking down at Gabriel and motioning her hand toward him. She might be reaching her hand out to receive the branch from him, though he doesn't appear to be extending it out to her. There is an object to the right of her which appears to be a placeholder for books or other text.
They all have golden halos above their heads with teardrop-like patterns inside. These don't seem to be floating, but rather just placed on their heads somehow, without obeying laws of gravity. Their robes are all shown with very exaggerated drapery and wrinkles, which gives this piece depth and adds movement to the figures. This is a style of painting clothing that was popular during this era of the Renaissance.
The architecture painted displays a very classic Italian Renaissance style. There are two arches on either side of the subjects, and we look in through the arches to see the scene. Behind the figures there seems to be a garden of small trees and one which is almost as tall as the buildings surrounding it. This tree is positioned in line with Gabriel, who is standing directly in front of it. This may have been used to signify his importance and to make him a main subject, separating him from the other angels. The whole courtyard exhibits symmetry in the rows of trees and buildings that are on either side. The cityscape continues on in the background with churches and tall buildings poking above the skyline. The churches can be noticed by their pointed tower tops which stand taller than the other buildings.
A white bird flying behind the angels is wearing a golden halo as well. It appears to be emitting golden rays from its beak towards Gabriel and Mary. By Mary's feet is a cutout in the flooring just big enough for a vase of water to fit in it. The position of this vase creates a straight vertical line with the palm of Mary's hand. This brings the viewer's attention back to Mary.
The buildings and architecture have a great level of realism in this painting, but the figures' faces aren’t extremely realistic. Their bodies show contrapposto, however, which makes their stance more natural.  
The three scenes in the predella are similar to those in the Barbadori Altarpiece, from 1438.
gravity Italian Renaissance garden contrapposto realism angel Barbadori Altarpiece predella