sight line
Quick Summary
The sight lines drawn from the image in the reality plane (RP) to the artist's eye intersect the picture plane (PP) to form a projective, or perspective, drawing. The horizontal line drawn parallel to PP corresponds to the horizon. Early perspective experimenters sometimes used translucent paper or glass for the picture plane, which they drew on while looking through a small hole to keep their focus steady.
A sight line is a line extending from an observer's eye to a viewed object or area. In mathematics and art, this concept is fundamental to perspective drawing, a method developed during the Renaissance by artists like Filippo Brunelleschi and Leon Battista Alberti.123
This technique uses sight lines to project a three-dimensional scene onto a two-dimensional plane, creating the illusion of depth. The eye of the artist is connected to points in the landscape by these sight lines, which intersect a vertical picture plane to form the drawing. This mathematical approach, known as projective geometry, deals with the relationships between geometric figures and their projected images.2
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