In the side view we are looking at the side of the "drawing". The line labelled "plane of the drawing" might be the right edge of a piece of paper.

For convenience, let's place an x-axis along the bottom of the "drawing" and a y-axis along the left side. Consider the points, P and Q, where rays from points A and B (on the first railroad tie) intersect the "drawing" (as shown above). We can measure the values of x1, x2, and y . . .

. . . and then plot the points (x1,y) and (x2,y). These are the coordinates of the points P and Q on the "drawing".

Repeat the procedure for the other railroad ties.

by Jan Garner
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