Dave Tapsell
Vanishing Points Radii
Sketch showing the principle of using two pairs of radii, each pair centred on the distant vanishing points – for 2-point perspective – both horizontal and vertical. As long as these radii can be drawn it doesn't matter how far the VPs are away from the drawing centre. Using visual angular interpolation to work between the nearest points is not difficult, obviously the more angle points there are the easier it is. This method, I find, is far preferable to making (and numbering) marks on straight lines, because those marks are not equi-spaced, whereas those on a radius are.
This method is easily extended to cover 3 & 4 point perspective drawing
Vanishing Points Radii
Sketch showing the principle of using two pairs of radii, each pair centred on the distant vanishing points – for 2-point perspective – both horizontal and vertical. As long as these radii can be drawn it doesn't matter how far the VPs are away from the drawing centre. Using visual angular interpolation to work between the nearest points is not difficult, obviously the more angle points there are the easier it is. This method, I find, is far preferable to making (and numbering) marks on straight lines, because those marks are not equi-spaced, whereas those on a radius are.
This method is easily extended to cover 3 & 4 point perspective drawing