Creating a complex shape

 From:  Michael Gibson
5123.4 In reply to 5123.1 
Hi Scott, so one thing to keep in mind is that more amorphous blobby-ish types of shapes are not very well defined only by 2D profile curves and using a lot of 2D curves tends to be the primary type of modeling that NURBS is the most useful and strongest in.

So it's not like you would really see a great advantage in doing this style of model in MoI rather than in sub-d in Modo, it's probably more in the area of stuff where you would want to be doing in sub-d instead.

For models that have a stronger 2D element to them, that's where NURBS modeling will really shine the most as an alternate modeling toolset to sub-d since you can then use 2D drawn curves to construct large chunks of your model really quickly and accurately.

So the very nature of the model that you're targeting here is not really going to show you the main benefits of NURBS modeling, that's something to just generally keep in mind. Instead of working at the sort of "highest convenience level" you'll instead be working in more low level and advanced types of tools right from the get-go.



Anyway, though, for doing stuff like this in NURBS it ends to be better to not try to do too much all at once in one single surfacing operation, especially if there is a major transition in shape happening.

Instead you want to look for the transitions between major forms, and focus instead of building those major forms separately and then they get connected together either with fillets or blends.

To look for transition areas, look for places of the model that have a kind of tighter bend in them, like in your case see these areas here:



Those are transition zones making a connection between different broader forms. The broader forms would be these pieces here:





So generally you would want to try to model those broader form pieces individually (it's ok and even desirable to let them just stick through each other while constructing them), then they either get combined together into a single solid and have a fillet put in between them, or you cut back some empty space in between them and use the Blend command.

EDIT: and Burr above shows a good example of the kind of model that you would shoot for - notice there how he's built the larger forms as separate pieces initially like I describe above here.

In general surfacing stuff does not tend to work very well if you try to force too complex of a form that goes through a lot of different shapes to be the result of one single surfacing operation, basically with too many shapes trying to all apply pressure onto a single surface it will tend to over constrain things and make for ripples and lumps and things like that.

When you're doing surface construction you want to build a surface for each broad shape in the result instead, then transitions are added separately after that.

Another thing that can help is that you often times don't want to try to construct things to some irregular outline initially, instead make a broad shape that continues through the outline and then use a boolean or trimming operation to slice off the broad shape. A lot of times people with a polygon modeling background have difficulty with thinking about building extended parts like that.

- Michael

EDITED: 8 May 2012 by MICHAEL GIBSON