Unrapt a 3d object

 From:  Michael Gibson
2654.4 In reply to 2654.1 
Hi Gaston, only certain kinds of surfaces called "Developable surfaces" can be unwrapped into a flat pattern like that.

Basically the surface must have a completely straight edge in one direction as you move across it.

Anything that is curved in 2 directions at any spot on the surface cannot be unwrapped without distortion. Like for example if you try to flatten a sphere you can't make a proper flat version that you can reconstruct the sphere from by only bending the flat version back again (with no stretching).

If you do have a model that only has developable surfaces in it, then one possibility is to import your model into Rhino, which has an "unroll" command that can make the flattened version for you.

There is another tool available for making unwrapped patterns called Lamina design: http://laminadesign.com/ - but it takes polygon data and then calculates a flat pattern of the polygon data.

MoI does not by itself have any functions for that kind of unwrapping - it is somewhat of a specialized area so it may take some time before those functions can happen directly inside of MoI.


From your description, maybe instead of an automatic unwrap function you may instead need to kind of manually break your model up into some strategic pieces (for example if generally cylindrical maybe into octants) by cutting it with boolean operations, then arrange each of those pieces in a way that will be easier for you to cut, then reassemble the pieces afterwards.

- Michael

EDITED: 25 May 2009 by MICHAEL GIBSON