Vanishing point or three mutually orthogonal directions can be found. Vanishing point A vanishing point is a point on the image plane of a perspective drawing where the two-dimensional perspective projections (or drawings) of mutually parallel lines in three-dimensional space appear to converge. When the set of parallel lines is perpendicular to a picture plane, the construction is known as one-point perspective, and their vanishing point corresponds to the oculus, or "eye point", from which the image should be viewed for correct perspective geometry. Traditional linear drawings use objects with one to three sets of parallels, defining one to three vanishing points.
Point-to-point transit or connecting flights so baggage must be collected and rechecked even to transfer between flights booked at the same time on the same airline. Although there are many point-to-point airlines, most have at least a "homebase" airport where most flights originate or depart. The United States airport system was point-to-point, controlled by CAB, until deregulation late 1960s/early 1970s, and eventually the 1978 Airline Deregulation Act when they switched to the hub concept, until the advent of low-cost carriers, when point-to-point air transport increased. Some full-service network carriers operate the point-to-point model alongside the hub-and-spoke system for certain high-density routes between