Filippo Brunelleschi  (1377–1446 CE) was an Italian architect, designer, goldsmith, innovator, and sculptor. Around 1410 CE, Brunelleschi rediscovered linear perspective by conducting an experiment at the Cathedral Baptistery of San Giovanni in Florence, Italy.

Brunelleschi created a hole in a realistic perspective sketch of the Cathedral Baptistery. A mirror was held at arms length in front of the painting creating a site line. He matched the pattern in the mirror to the building, documenting that parallel lines converged to a single point. This experiment demonstrated that by using a mathematical system artists could re-create a three dimensional effect on a flat surface, giving an illusion of distance and depth.

There are three elements to create linear perspective:

• Horizon Line - represents the viewer's eye level.

• Vanishing Point is a single point on a horizontal line where all parallel lines appear to converge.

• Orthogonal - parallel lines recede into the painting and meet at the vanishing point.

Linear perspective is achieved by creating a mathematical grid of orthogonal lines to the vanishing point. Objects appear smaller as they get farther away from the viewer and closer to the vanishing point. 

Da Vinci's Ginevra De' Benci is the only Da Vinci painting on display in the United States (Washington, D.C. National Gallery of Art) and is an example of portrait realism using newly discovered painting techniques. In the portrait, Da Vinci used gesso techniques with slow drying oil paints to create depth. He positioned De'Benci facing forward, compared to side portrait profiles from the early Renaissance, in three-quarter format to add to the realism. Da Vinci experimented with light reflections off De’ Benci’s skin, adding a natural effect to the subject. He even used finger painting to create delicate features throughout the artwork.

The focus on individualism and realism embodied the humanism movement. Portraits’ became widespread during the Renaissance with three-quarter, three-dimensional, front-facing views to produce perspective into personal characters. Experimentation occurred with bold pallets to create realism and enhance depth, especially true of Venetian artists. Innovations’ included oil paint medium, techniques as the use of gesso, and bold pigments. 

Oil painting became a dominant medium because of its slow-drying, transparent quality which allowed artists to create greater realism, depth, and subtle color effects through layering and blending. The use of gesso, a white primer such as calcium sulfate dihydrate prepared with parchment glue, provided a smooth surface for painting and layering. Pigments used included arsenical sulfides, realgar for brilliant golds and oranges; lapis lazuli for blues and greens; copper acetate for bold greens; and Venetian red for warm earth tone.

Giovanni Bellini and Titian’s Feast of the Gods (1514-1529 CE) can also be found at the National Gallery of Art in Washington, DC. The painting represents a mythological image, with gods realistically represented in human form. Bold colors of the Venetian paint pallet were used to create depth and realism. These included indigo, the arsenic pigments of orpiment and realgar, and the copious use of the deep green copper acetate. It is notably one of the few paintings to use orpiment and realgar to create the vibrant oranges and yellows, both substances being extremely poisonous.