paraline drawings

Scaled orthographic drawings, such as plans, elevations and sections disclose the relative measure of only two dimensions at a time on a 2-d drawing surface. The viewer/user can put a ruler anywhere on the page to obtain information about the virtual object. Only 2 dimensions at a time can be related.
Machinists, cabinetmakers, architects and planners use paraline drawings to represent a third dimension on two-dimensional paper, while retaining the measured precision of 2-d orthographic plans, elevations and sections. Paraline drawings, while depicting objects "from above" or "from below," don't implicate any particular observer. Paraline drawings retain scalable lines useful to construction. Sets of lines that are parallel in the virtual object remain parallel in the 2-d paraline depiction.
Linear perspective drawings describe 3-d volumes and spatial relations on a 2-d surface as they appear to the fixed gaze of an observer --- the audience looking at the drawing. The observer is implicated in the virtual scenario.