Freehand Ellipses In Perspective
I found this amazing trick yesterday: a Youtube video by darthfurby (https://www.youtube.com/watch?v=INTcLy18Tms) in which it explained how to create 12 points on a circle, in perspective. I've since worked out that it is an approximation, but a very good one.
You start with a perfect square and draw diagonals fron opposite corners. This gives you the center point. And you draw the horizontal and vertical line through that center point, dividing the square into four equal squares, also giving you the first four points on the circle: