In a linear perspective drawing , orthogonal lines are the diagonal lines that can be drawn along receding parallel lines (or rows of objects) to the vanishing point . These imaginary lines help the artist maintain perspective in their drawings and paintings to ensure a realistic view of the object.
In mathematics , orthogonality is the relation of two lines at right angles to one another ( perpendicularity ), and the generalization of this relation into n dimensions; and to a variety of mathematical relations thought of as describing non-overlapping, uncorrelated , or independent objects of some kind.
VANISHING POINTS , which we have drawn in BLUE , are dots on the eye-level where parallel lines seem to converge and disappear. Both illustrations on this page use a single vanishing point and demonstrate the simplest form of perspective drawing: One Point Perspective.
1570s, from French orthogonal , from orthogone , from Late Latin orthogonius , from Greek orthogonios "right-angled," from ortho- "straight" (see ortho- ) + gonia "angle," related to gony "knee" (see knee (n.)). Related: Orthogonally .