Perspective drawings utilize various methods to create the illusion of depth and space. Among the options presented, the one that is NOT typically used in perspective drawings is:
using a vertical line to establish where the sky and ground meet.
This is because perspective drawing primarily relies on horizontal lines, vanishing points, and the scaling of objects to create depth, rather than a vertical line to denote the horizon line. The horizon line helps in establishing the viewer's eye level and the location of the ground and sky meeting, but it is not represented as a vertical line.