Monday, May 23, 2011

Circles in Perspective - Part One

A circle


viewed from an oblique angle, or squashed (scaled on one axis), becomes an ellipse:


An ellipse is symmetrical on both center lines - all four quadrants are the same shape (some are mirror versions of the others). The long center line of an ellipse is called the "major axis", the short center line is the "minor axis."

But shapes in perspective are not symmetrical - they get smaller as they recede into space, right? For example, a square in perspective looks like this:
So how does our perfectly symmetrical ellipse fit into all this? Answer: the center of the perspective circle lines up with the center of the perspective square, but the center of the ellipse representing it does not:
So the top "half" of the perspective circle is a very different size and shape from the bottom half:
But the ellipse is still... a perfectly symmetrical ellipse:
Kind of odd, but there it is. In the next installment we'll see how to orient and fit ellipses into a perspective drawing - perhaps there will be some more surprises there...

Go to Part Two

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