Creating an isometric drawing from an isometric projection

Useful shortcuts, tips and techniques
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Zlyx
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Joined: Thu Jun 15, 2006 3:56 pm
Location: Sundre, AB, CANADA

Creating an isometric drawing from an isometric projection

Post by Zlyx » Wed Apr 16, 2008 5:23 pm

Some CAD apps. (eg., SketchUp) export isometrics as projections instead of drawings. What's the difference, and why should you care?

Well, if you're hoping to take dimensions off of a merged isometric, you'll find the numbers wrong. That's because an isometric projection uses an isometric scale, not a true scale. Happily, the two are related by the simple formula:

isometric scale = (sqrt (2/3)) x true scale

Solving for true scale:

true scale = ((2/3)^(-1/2)) x isometric scale = 122.4745% x isometric scale

In practice, this means that you can use HighDesign's scaling tool on a selected object, scaling it by 122.4745%, to get an isometric you can pull dimensions off of.

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