« Nodal Point Pan and Tile: Part 3 | Main | One Point Perspective »
November 28, 2004
How to Draw Ellipses
I was intrigued by a tutorial I found on artist Scott Robertson's web site drawthrough.com on how to freehand draw ellpses. I found it extremely educational, and wanted to play around in 3D with what I learned there.
His first main assertion, which I see a lot of people get wrong, is that when a circle in 3D space projects into 2D as an ellipse, the center of the circle and the center of the ellipse are not the same point. That much I already knew.
His second assertion, which I found particularly interesting, is that in such a situation, the minor axis of the 2D ellipse is the same as (or is at least parallel to?) the normal axis of the original 3D circle. In the case of a car, the minor axis of the 2D ellipses is parallel to the axle of the car. In the case of an airplane, the minor axis of the propeller's ellipse in parallel to the drive shaft.
I like to test things. Here's what I got when I did.
My results agree pretty closely with his predictions. Close enough that I think I'll be mindful of whether or not I'm following his suggestions when I draw.
The results of my experiment didn't look "dead-on," however. My own inaccuracy orienting the red axis along a vertical line and in hand placing the 2D test ellipses might be one source of the error.
Another source might be in the way in which the original tutorial depicts objects in perspective. Even when Robertson draws the X- and Z-axes of an object in perspective, he maintains the Y-axis perfectly vertical, as if he were using a view camera, or a kind of draftsman's perspective not produced by typical cameras.
Posted by digital artform at November 28, 2004 02:23 PM