Hi Steve, yes a Network has to be arranged in such a way that it forms a grid pattern, so that it can be essentially unwrapped to a 2D pattern. It's similar to how latitude and longitude lines on a globe can get unwrapped to a 2D flat map.

Could you post a 3DM file attachment with the curves that are acting strangely? That would let me take a look and describe what the problem is for your particular situation.

Here are some links to some previous discussions and examples of the kinds of layouts that won't work, maybe one of them applies to your example:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1905.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=1778.6
http://moi3d.com/forum/index.php?webtag=MOI&msg=3086.19
http://moi3d.com/forum/index.php?webtag=MOI&msg=3624.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=1484.12

- Michael

Thank you! that is so helpful, I was not thinking it worked like that I was imagining that what ever framework you created the "cloth" would be stretched around it. I am going to rework the model and see if it works.

Still not working here is the model

Hi Steve, so the deal here is that your outer curve is not quite as it seems - it has an extra segment in it that makes it loop around on top of itself.

If you look at this area here closely you can kind of see it's a bit darker:



Then if you use Edit > Separate to break it apart into segments and move this segment over, that will help you to see the extra portion where it was wrapping around on top of itself:



So you'd need to clear that up in order to do a network with it.

But also you're going to have some difficulty trying to build a network with curves like this which have such significant differences between their shapes. You'll get a lot of pinching and bunching type effects trying to collide such different shapes together into a single surface like this.

So for example the curve you have here:



Is very very different in it's overall shape than the other on the other side here:



Trying to build a single surface is going to try to force the surface to incorporate each of those very different shapes being blended together, you're not going to get a good result with that type of stuff.

Also contributing to the problem are the sharp corners in some areas, like here:



Those sharp corners will kind of make sharp areas that sort of radiate out from them as the sharp-cornered curve is being blended with the other curves in order to build a surface - Network involves a sort of blending together of the shapes involved to build a surface.


So instead of trying to build something like this all out of 1 network surface, you would probably want to make a more simplified larger sheet and then trim away some spots with side profile cutting curves to make sharp cutouts and stuff like that, rather than trying to build a cutout directly into the initial surface itself.

I'll try to make an illustration.

- Michael

Wow you work fast! Thanks for taking the time to explain all in such detail, I am starting to understand. I will try a different approach and post the results.

Thanks,

Steve

Hi Steve - so here's a bit of an example for how you could build a more simple extended surface with Network, and then use Trim to make cutouts rather than trying to build the initial surface directly to a more complex outline right all in one shot (which then tends to distort the surface, particularly with sharp corners in the outline curves causing corresponding sharp features in the generated surface).

I've attached the 3DM model file if you want to look at the curves.

So here's the kind of curve structure where it's a more extended and more simple sheet:



Then build a Network with that:



Now to produce the cutouts you actually cut the surface - make a cutting curve in a side view like this:



In the 3D view you can see how the surface and the 2D cutting curve relate to one another:




Then select the surface and use the Trim command, and use the 2D curve as the cutting object - that will project the curve onto the surface and slice it, pick this area to discard:



And you can see how you can get sharp cutouts and details like that, but have a smooth surface:



A lot of times if you have irregular outlines especially with sharp corners on it, putting those details in by trimming can be a lot better than trying to incorporate the irregular outline directly into the initial surface construction.

This kind of strategy of "build an extended shape and then cut it" tends to be pretty frequently used in NURBS modeling, it's one of the things that makes NURBS modeling significantly different from poly modeling.

Sometimes it can help to think of it more like an actual physical construction process where you'll have some piece of stock that then gets pieces of it cut away.

- Michael

Hi Micheal,

Now I understand! thank you for the very detailed example. I assume the same concept would apply to lofted shapes etc. I am going to slog on with the car model and post results and questions.

Thanks,

Steve

Hi Steve, I'm glad that helped!

> I assume the same concept would apply to lofted shapes etc.

Yup, the same thing applies there as well - if you have some kind of irregular shaped boundary you probably don't want to try to loft directly to that boundary initially, instead you'd want to make a larger smooth surface and them trim it to produce the final boundary.

Here are a few previous posts with some similar cases where building an extended shape and then cutting it was the best strategy:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3795.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=3321.17
http://moi3d.com/forum/index.php?webtag=MOI&msg=3105.7


You usually want to do this kind of strategy when you've got some kind of surface shape that has looks all nice and smooth but then has an edge in it that suddenly cuts the shape off. It is easy to recognize this when the cutoff is an internal hole in the surface, but the same thing applies when the cutoff is slicing the outer edges of the surface as well.

- Michael