Whether produced on computer or paper, most 3D design relies on 2D representations for accurate description of objects and their positioning. Maps, plans, cross-sections, and elevations are all examples of 2D representations. Each of these views represents an orthographic view.
Perspective views most closely resemble human vision. Objects appear to recede into the distance, creating a sense of depth and space. For most 3D computer graphics, this is the view used in the final output that the client sees onscreen or on the page.