Great circles transform to straight lines via the gnomonic projection. This route shows as curved on any map except for one using a gnomonic projection. A straight line drawn on a gnomonic chart would be a great circle track. Popko notes the projection can be gnomonic too. The Vertical Perspective is related to the stereographic projection, gnomonic projection, and orthographic projection. The gnomonic projection is used for charts intended for plotting of great circle routes. The gnomonic projection is used extensively in photography, where it is called "rectilinear projection".