Is it important to build surfaces with single span curves?..because it can introduce knots or added isoparms? Is this important when creating surface that are attached together to maintain good curvature?

What was confusing to me using Alias..was if I ensure all my curves g1...why do I have to set, through another option box that the surfaces are g1 also. Shouldn't this be automatic or simplified? Maybe Moi could be more intuitive that way.

Hi dejule,

> Is it important to build surfaces with single span curves?

Not necessarily... It totally depends on what your goal is and what you are trying to do.

Many kinds of primitive surfaces for example a sphere or a cylinder are made up of surfaces made up of multiple spans.

Just having multiple spans does not in itself automatically mean there is a problem.


There really isn't a good answer to your question without putting it in some more context - what are you intending to do with these surfaces, what is their final goal, are they going to be turned into polygons or sliced into sections for manufacturing that will render any worries about super high degrees of continuity to be meaningless?

Is there some particular problem with multiple span curves that you are trying to avoid?


- Michael

Hi dejule,

> What was confusing to me using Alias..was if I ensure
> all my curves g1...why do I have to set, through another
> option box that the surfaces are g1 also.

Are you talking about a tool in Alias or a tool in MoI here?

If so, then which tool?

It is hard to know what you are mentioning here without some more context.


Due to the nature of how NURBS surfaces work, it is not unusual though for there to be different qualities to a surface in the U and V directions.

For example a surface can be of degree 1 in U and degree 3 in V.

Just because you have a certain structure in one direction does not necessarily mean that the other direction which is formed during construction must have the exact same kind of structure to it. That's why there can be some options like that in some construction tools - they are basically referring to the new direction that is being created, not to the direction of the existing curves.


> Shouldn't this be automatic or simplified? Maybe Moi
> could be more intuitive that way.

In which tool?

- Michael

Michael thanks for this infos...i'm new to nurbs world and Moi is my first nurbs based program....so...i'm learning them with Moi and with all the notions that i'm learning here on the forum :)
;)