Hi All, I'm Glenn.

I'm new to Moi and new to nurbs modeling.
I finally found some time to start to get to know Moi a bit.
The tutorials and the forum already helped me with some of the basics, so we are getting there step by step.
I guess that working out the correct strategy to model is the most difficult part.
So be sure to hear from me again on this forum,because I will definitely need some tips in the near future! :)
By the way, most guys on this forum and tutorials make it all look to easy!!! respect for you guys! ;)

So to get down to my topic/

Today I noticed that when I zoom in on my model, that there are spaces between the arcs I drew and the actual curved surface.
When I draw an arc in Sketchup for instance, I know that I can increase the number of segments to get more accurate and smooth result.
Since I'm new to this nurb modeling, I'm not sure if that is also the case here?
I think it's not.
Also the actual arc that I drew doesn't show the same segmentation, and there are no options to specify the amount of segments..
I must say that the segmentation is only visible in close up, its not visible when i look at the entire model.

So my real question is..
Am I just looking to close at my model and there is nothing wrong?
Or did I do something wrong in the process (change a setting?) and my model is in fact not detailed enough to give a smooth surface.

I'm asking because eventually I hoping to export and CNC carve and/or 3D print some of the models I make.
So I would like know if I'm doing anything wrong from the start.

Ok, I think I just figured it out.
When you export you can change the amount of polygons to get the smooth finish without segments.
So it's just a visualisation thing and i'm being to precise...

Am i right?

Hi Glenn, welcome to MoI and to the forum!

> So it's just a visualisation thing and i'm being to precise...
>
> Am i right?

Yup, you're right! In order for a surface to be displayed it has to be broken down into triangles. You can sometimes see evidence of this triangulation in the display, especially if you zoom in closely and it can also be fairly more pronounced on surfaces that are sort of wide and only shallowly curved.

That particular kind of thing is just a display artifact and does not indicate any actual problem with the surface. The real surface is actually smooth there and as you already discovered when you go to do an export you can choose a high mesh density at export time if you want a smoother result.

The real-time display is more oriented around doing things quickly, so that you don't have to wait any extra time to see your model when you've just made a change to it.

Curves though are drawn in a pretty different way - they are dynamically broken down to be smooth looking at the view's current zoom level so you won't see curves or edges with that kind of thing, only the shaded surface part.

So yes what you are showing there is totally normal and is just something to ignore. There are other kinds of artifacts that can actually indicate a problem, but they look different than that, more like stuff sort of "leaking" out beyond the boundary rather than looking like line segments inside of the edge.

When you have 2 surfaces joined together at a common edge, they will have a common triangulation at that juncture so it's harder to notice this particular side effect on joined areas as compared to open edges.

- Michael

Also if you're new to NURBS modeling but have previous experience doing sub-d polygon modeling, check out here for some links to discussion and tips for people who are coming from that kind of background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

NURBS modeling has a pretty different approach from polygon modeling and it can be problematic to try and use poly modeling strategies instead.

One of the main differences is that booleans and intersection methods are a primary way to do stuff with NURBS modeling, and instead of manually drawing every single final edge of your model to start with you usually instead want to draw primary profiles that make extended basic shapes and have other portions of the end 3D model come from intersections with other objects or profile curves.

I've noticed that often times people from a sub-d modeling background try to draw in a big network of curves to start with rather than using booleans.

- Michael

Hi Michael,

Thanks for your quick reply.
It sure is some getting used to after sub-d modeling, but we are getting there. :)

Thanks for the advice, i will give the other discussions a look!

I'm experimenting with the FLOW command for now!
Love it!!