Perspective Projection, Pictures for Geometry, Albrecht D羹rer, 1532. D羹rer woodcut of Jacob de Keyser's invention. With de Keyser's device, the artist's viewpoint was fixed by the eye of a large needle inserted in the wall. This was joined by a silk string to a gun-sight style instrument, with a pointed vertical element at the front and a peephole at the back. The artist aimed at the object and traced its outline on the glass, keeping the eyepiece aligned with the string to maintain the correct angle of vision. Perspective, in context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects. Perspective in the graphic arts, is an approximate representation, on a flat surface, of an image as it is seen by the eye. The artist uses intuitive, artistic, scientific, or technical skills to represent the phenomenon of the visual perception of perspective.