im just playing around and have never really applied myself to nurbs modelling.

i have this cell phone-ish model here and wondering what the best way is of putting a top on it

ive done a planar surface, then ive lofted the top, but i think what would be better is a blend surface
so i could maintain tangency between the top and the sides.

im attempting this with the planar top and the sides but it keeps asking for curves, which i give
then i guess it fails as no surface results

any help appreciated...also is there a general resource page of nurbs modelling tips which people
reference... i often did that im a bit lost as to how to go about a surface...for example i want to do
a filet but i have to deal with multiple underlying surfaces and how to blend them all seamlessly and things like that
then il start just rebuilding things as lofts cause its easier but maybe not as nice a look

Hi blade33ru, what you really need to select for Blend are _edges_ not just plain curve objects.

If you have some of the generator curves still sitting around that you used to create the surfaces, those are probably sitting right on top of the surface edges that you want to select. If that's the case you'll need to select those original generator curves first and either delete or hide them to get them out of the way so that it will then be possible to select the edges that you want to blend.

- Michael

If you are providing it with curves, then you will get a blend curve which you can the sweep around the curves you selected... If you have one edge and a curve then blend fails for me too. Use moi browser and turn off the curves by clicking the eye icon, then try the blend again and when it asks for the curves select the edges of the existing surfaces, you should then get a blended surface.

Martin Spencer-Ford

ok thats interesting....should join all the edges first? the top planar surface is all one edge...maybe it would be more congruent..?

ok got the blends working...had to one by one but looks nice...one other thing...i notice there is a history button...that woudnt allow me by any chance to change the look afterwards would it?...i ended up doing like 6 blends and after making all the selections it would be kind of a pain to go back and do it all again to tweak the look....im a maya user...used to have the history running

Hi blade33ru,

> ok thats interesting....should join all the edges first?
> the top planar surface is all one edge...maybe it would be more congruent..?

Join with edges selected with make a curve object. There is a different "Merge" command that can combine 2 edges together into one edge, but only when there are only 2 edges meeting at a common merge point and they meet up smoothly there.
http://moi3d.com/2.0/docs/moi_command_reference10.htm#merge

It's a little more common to actually need to split up edges in order to match up pieces to blend, you do that by selecting the edge and using the Edit > Trim command with the "Add trim points" button.


> ok got the blends working...had to one by one but looks nice...

Yeah right now Blend is limited to only working between a pair of edges at a time. I am planning on improving that in v3 to work on a longer selection of edges on each side instead of only one on each side.


> i notice there is a history button...that woudnt allow me by any chance to change the look afterwards would it?

The history is pretty limited - it will update if you move geometry around like for example if you make 2 planes and do a blend between them you can then move the planes around and the blend will update.

But it only responds to geometry edits right now, there isn't any UI set up for editing other stuff like parameters.

That is something I want to work on in the future, but it's quite a long ways off. If you need to make those kinds of parameter adjustments later on, you might want to look at a "parametric" modeler instead of using MoI, something like SolidWorks for example. They are much more focused on lots of history oriented stuff. MoI is more focused on making it really quick and easy to do the initial creation of stuff and no so much on altering it afterwards.

- Michael

Also check out here for some other strategies for this kind of a shape:

http://moi3d.com/forum/index.php?webtag=MOI&msg=1002.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=3137.2

- Michael

thanks...useful information and the links are exactly my next question -- how to make a curves screen surface

and the blends worked pretty ok for what i got now




i think solidworks may be more power than i need..im just looking for an easier way than sub d modelling for more technical items...i mainly do commercials....i played around with rhino a few year ago ..is that more of a middle ground maybe?

thanks

Hi blade33ru, Rhino has a lot more commands than MoI for doing all kinds of specialized stuff (including more advanced blends right now), but there isn't really any difference in the particular area of history parameter editing. MoI and Rhino are basically about the same in that area, it's also not an area that Rhino is particularly focused on either.

- Michael

i like parametric...on the other hand the simplicity here is key...this is the most productive ive ever been with nurbs...usually I get clogged down in the interface.

i followed that other thread of curved surfaces you out up to create this shape ...it was really easy.

i cant tell you how pleased I am!.

this could be a good educational product to teach modelling concepts...i teach classes in maya and pretty much no one is teaching nurbs in the visual effects fields anymore, but i know students would dig this a lot...they get pretty lost trying to maintain proper edge flow and adding extra edges for detail. this is so much more direct and logical

also i was thinking, alot of the world has moved to subds for modelling pretty much everything, but there are great advantages with nurbs for this kind of stuff...with number one being its really easy. still it would be useful and maybe marketeable to retain sub d concepts like edge loop and edge ring selections but to tangent curves or nurbs edges as we have here.

great product this

Hi scott, yeah the main focus for MoI is on getting things drawn really quickly and fluidly.

Usually other CAD programs that focus on history have a lot of additional setup stuff that you have to do as part of the workflow, like before you can draw you have to pick a drawing plane, engage certain modes, and stuff like that. There is typically more process involved. That can pay off down the road for making adjustments but it can also tend to really stifle just the basic drawing and initial creation process, sometimes making things complex enough that the whole program requires quite a bit of training in order to operate.

MoI is set up to try and bring the primary beneficial essence of NURBS modeling (which is basically building shapes primarily by 2D profile curves) to be more approachable.

It can be a great companion to sub-d modeling because a lot of man-made objects are very well defined by 2D profile curves, and have cut out areas which can be very labor intensive to model with sub-d techniques where to make even a basic hole you have to be a kind of master of topology. With NURBS modeling to make a hole you just draw a 2D curve and do a boolean.

> still it would be useful and maybe marketeable to retain sub d concepts like edge loop and
> edge ring selections but to tangent curves or nurbs edges as we have here.

Really the NURBS process is strongest when you're using 2D profile curves for the majority of your work other than selecting edges for filleting. The overall workflow is really different from sub-d so it's not really that feasible to try and make it resemble sub-d, it's a completely different kind of technique.

But that difference is also why it can be useful as a companion since it can just do a better job (more quickly and easily and also more accurately) of certain kinds of shapes.

If your model is more organic or semi-blobby in shape then that becomes a better fit for sub-d modeling techniques. The more that your model is strongly defined by 2D profile curves with holes or cut out areas in it the more it becomes suitable for NURBS modeling techniques.

But the overall approach of NURBS modeling is pretty different than sub-d - you want to rely on 2D curves a lot more and also rely on booleans and cutting operations as a primary way of doing things. That can take a little while to sink in for people from a sub-d modeling background who are used to avoiding booleans at all costs. Instead with NURBS modeling often times building things as a simple extended piece and then using booleans should be the main approach.

Check out here for some links to discussions and general tips for people who are coming from a sub-d / poly modeling background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael

hey thanks for all the info ...very useful...

u might be interested that i just installed a demo of autodesk inventor and was pleased to see they extend the idea of edge loops into their nurbs modelling environment. a small detail but it works nicely. still for 8 grand maybe i can live without it, lol

Hi scott, yeah there are a few NURBS modelers that try to incorporate sub-d modeling techniques by giving features to start with a block and then squish it into some completely other shape.

However, that general overall strategy is not really where NURBS truly has its greatest strengths. If you are trying to model that way in NURBS you probably should just be modeling in a sub-d program instead where the whole package is totally oriented around sculpting and organic shaping.

NURBS modeling has its greatest strengths in the area of generating surfaces and cuts from drawn profile curves (I'd compare it more to "illustration" or "construction") rather than in squishing things around (which I'd compare to more like "sculpting"). If you try to do the same kind of process in NURBS as you do in sub-d you're not really gaining that much since you already has that kind of process covered very well in your sub-d modeling tool, in order to gain the greatest benefits of a different tool you have to more embrace that there is a different workflow orientation to it.

If you're looking for no change in workflow the easiest way to achieve that is to just stick with what you've got already rather than trying a new tool in the first place.

So in other words, I'd recommend looking at differences in workflow and modeling strategy to be a good and useful thing, not really a defect! ;)

- Michael

interesting points. thank you!