# How do I translate an extruded elipse to Pepakura?

Discussion in 'Tips, Tutorials & Tools' started by BazookaJo, May 31, 2006.

1. ### BazookaJoMember

Hi there

Starting the epic journey of translating my 3DS model into a Pepakura kit.

Having problems straight away getting simple round shapes (e.g. simple wheels) to translate properly into Pepakura.

The problem is that the sides of the extrude seem to be made up of a large number of polys which really should be be nothing more than one continuous side peice (to be cruved around the flat circular top and bottom sections).

Any ideas how to approach this problem

Joe.
2. ### buzucNew Member

Do you have a screen shot of your development ?

So whe can see clearly your problem. When I make rounded part (cylinders, ellipsoides...) I try to make them with only a few poly. For example a simple cylinder with 6 sides will be seen the same in pepakura as a 24 sides cylinder.

Am I clear enough ?
3. ### BazookaJoMember

Hi Buzuc

Going to post some pics of the development when I've tidied it up a bit:grin:

Do you mean that you would multires as 25 sided cylinder to a 6 sided one?

To be fair, I think it may be a problem with the original model. Objects I've extruded straight from 2D vectors seem to go in as one continuous peice whereas flat extrusions from the polys of existing 'softer' shapes seem to shatter on contact with Pepakura.

Maybe I need to rephrase the question with emphasis on 3DS.

Best regards

Joe.
4. ### wunwinglowActive Member

Any software that creates a 'mesh' model 'corrupts' the initial 'pure' shape by converting it to triangles. If the shape is angular and made from flat faces, no problem. However any curved edge will get converted into a series of straight lines. Welcome to the major limitation of using meshes!! With an extruded circle, the circular faces get converted into polygons, and the extruded face becomes a ribbon of triangles alternating point to base, their base edges matching the length of the straight edges of the end polygons. If you make the polygon edges shorter and shorter, the difference in overall length becomes less and less and the unwrapped parts will approach the shape and size of the unwrapped 'pure' surfaces. But if you want a perfect unrolling, you need to work with a NURBDS modelling program, like Rhinoceros (www.rhino3d.com) although here is a little secret; Rhino uses precisely the same process to calculate its unrolled surfaces! Don't tell anyone who told you though.....

Tim P
5. ### BazookaJoMember

Aw damn!

Guess it's a manual job then, unless I can figure something else out.

As I said before, it seems to be okay when you extrude from an imported vector, as instead of triangles you get what looks like a series of rectangles.

I'm also guessing it should be okay extruding from a spline, as the same thing happens.

I will continue to play...

Thanks again.

Joe