re:
> maybe it's a bad idea, but I think it could be good for complex surfaces.
It's not necessarily a bad idea, but it's an overall area (complex surface sculpting by control points manipulation) that MoI is not focused on because it's an advanced area of modeling that has a high learning curve.
> and I can add that this surface iso points with "Add pt" but why I can't delete a iso point line?
That's because you can only mainpulate NURBS surface control points by adding or removing a full column or row of points, not just any individual points and there are not tools in MoI for targeting rows or columns of points. Again because that's part of a complex higher learning curve modeling strategy that is not currently a focus area for MoI.
You would generally be better off doing these types of things in sub-d modeling program rather than in MoI. Those programs are focused entirely around this strategy of manipulating control point cages while MoI is not.
However a few car modelers who are also car designers have recommended NURBS over sub-d as they claim that is what is used in the field. And a NURBS based STL model is much preferred over a sub-d produced OBJ in manufacturing.
re:
> However a few car modelers who are also car designers have recommended NURBS over
> sub-d as they claim that is what is used in the field.
Yes it's true that NURBS are used by actual car manufacturers. But those are people who have 10+ years of experience climbing the difficult learning curve for a specialized area of modeling.
For most people it's not practical to take that approach, they need something that doesn't take 10 years to learn how to use.
I find it quite frustrating that there are very few car modeling video tutorials for MOI3D. Yet we see what can be accomplished when in the hands of a very talented modeler like Kuechmeister Swagger. However I am quite perplexed why there is never any audio. I find it rather difficult to have one eye on the screen watching the modeling process and my other eye trying to read the text. Adding an audio track would make the process so much easier to follow and understand.