Scale of imported curves

by DMG

So a simple example of my problem is this:

* Say I have a 10mm square frame in Affinity designer, and I export it as an .eps.    

* When imported into 3DCoat as a curve, it is now a 28.346mm square.  Why the different size?  Why such a random amount? (And why can’t I see a ‘bounding box’ size for a curve in 3DCoat so I can just tell it to be the right size?)

The answer lies in the fact that Affinity Designer (and probably plenty of other vector art programs) work internally in postscript points. 

72 postscript points makes up 1 inch.  It is also equal to 25.4mm.

If you divide 72 by 25.4 (to get the dimension of 1mm in points), you find that 1mm equals 2.8346 postscript points.  And that’s the reason for the scale discrepancy, and the exact amount.

So to scale a curve correctly in 3DCoat, it just needs to be reduced to (1/2.8346) or 35.28%. 

The easier solution by far if to work in points instead of mm in Affinity Designer, and 3DCoat will import points as the default unit measurement, and it’ll work out right without having to endure any maths.