CONSTRUCTION OF THE SYSTEM

1 —	Construct square A drawn to scale.
2 —	Calculate the distance of 17cm from the middle of square A base downwards. Determine point a.
3 —	In the upward direction, draw a vertical line of 1.70m from bottom to top of point a and mark point b.
4 —	Construct a square with the same dimensions of square A on the line constructed between points a and b. See square B in figure 4.
5 —	Draw a horizontal line crossing the two squares at point b height.
6 —	Draw a diagonal line from point c to point d (see figure 4).
7 —	From the vertices of square A, draw lines that vanish in point b.
8º —	Determine point f at the intersection of the lines that join points e, b, c and d.
9 —	By joining points f and g with a horizontal line we will have a horizontal plane.

NEW BASIC CONCEPT

The horizontal plane results from the overlapping of two images 17cm. apart from each other.