HOW TO WORK IN OBLIQUE PERSPECTIVE WITHOUT DRAWING A PLANE IN SQUARES
First of all, locate on the horizon line all vanishing and depth points and the measurement points 1 and 2.
Note that in oblique perspective, the edge of the first plane (measurement line of 1st magnitude) is the one that distributes the measurements. The same applies to the depth and width measurement lines.
The cube drawn in the space results from the square executed on the floor and from the measurement calculated on the measurement line of the 1st magnitude. The dotted line that runs to the vanishing points 1 and 2 transfers the measurements to the desired width and depth.
See figure nº 44 (next page).