Hi there,

i am working with MOI now for about a week and i am making good progress. But now i am stuck with
a quite speical piece of geometry, which i not get modelled the way i want it. In the picture you see
what i want. The hooks i get done now (also with help of the forum, Thanks guys), but the Y piece
drives me crazy. As you can see in the picture, it ultimateley needs to be connected to the hooks.
I already tried sweep and surface network and did not come to a satisfiying result.
How would you approach such a shape?
Best regards,
Heiner

PS: I attached a file, if you want to see the whole thing in more detail!

Try to imagine making it without the chamfers and fillets. Boolean together the basic forms and then chamfer/fillet as a final step(s). I think of this similarly to 2D vectors where you are trying to approximate a curve and its choppy and bumpy because you have too many points when the solution is to have just the "right" amount of points and carefully controlled Bezier handles. In 3D it can be more complicated because there are more factors than just points and handles you have things like chamfers/fillets and such.

Hi Heiner,

You're really talking about an object that can be quite complex.

Questions to ask...
Does it have to have tangent surface edges with its adjacent structures? Does it have to be smooth in form?

I think the best way to make that shape is with a series of Networks to make the main splits, then some trimming and more Blends until your form takes shape.

I tried the new N-Sided on it (just for kicks). It's great if you're going for that 'rubber-coated' look, but not the best solution for this.



Try constructing each rounded edge between the sides of each opening with techniques you know work, such as Sweeps, then you would have to use Blends or a Network to build up the rest. But it would have to be in sections for sure, because no one single surface can make that.


I know I wasn't much help here... this is the type of object I've struggled with as well. It will be interesting to see other solutions.

Okay... Here's another try:




I did Sweeps to make up the contoured sided, then I made Blends to match the edge regions of each section... I used Trim, of course to get my shorter edge sections.

Just for fun I formed the middle region with the new N-Sided tool.

It's not perfect, but it represents another approach, but with a little more control.

welcome aboard Heiner
i checked your model in ortho wiews:no one spline is flat...messy points,at first sight...
Mike showed you some ways to get your shape
my suggestion is to draw your contour splines in TOP wiew,hooks included,all planar
then use construction tools to get thickness you want and try to use flow tool to bend just the hooks

M

Hi Heiner, an approach could be to to model it in two parts, then slice each one (red lines) and blend the two.

Marc

Hi Heiner, as you get to shapes that are not very well defined by 2D profile curves they can be difficult to create with CAD toolsets and often times polygon modeling toolsets are a better match for things like that.

It looks like you already have this modeled in polygon form - why is it that you're trying to model it again in MoI ?

You might instead want to look at t-splines or nPower sub-d NURBS conversion tools which can convert an existing sub-d model into NURBS form, if you're trying to get your polygon model into something like SolidWorks for example.

-Michael

Heiner,

Maybe you should consider an analytical approach. Or in other words, just build your shape using basic boolean methods:



I made the top and bottom surfaces, which were more broad. In this case, I extruded two curves, but a smooth and simple Network of what you would like to portray as far as the overall shape would do.

From the top view, I made three curves representing the curvy areas, three lines to represent your openings, and an Inset (offset) of the curves to represent the inside.

I trimmed the top surface with the more inner curves and kept that shape.

I extruded the more outer curves downwards, then I trimmed them with the bottom surface. I also derived my bottom surface shape from those curves.

I then Blended surfaces between the edges of the more smaller top shape and the vertical surfaces of the extrusions.

I did some extra trimming, but then I was able to join everything together.

I used the straight lines to trim the openings.

The bottom had a sharp lip and I applied some fillets.


So with some brute basics, I was able to outright create a shape close to maybe what you were envisioning.

But like Michael mentioned, the more organic a direction you intend to take, the more you may have to consider D-Sub like applications such as T-Splines which takes a more organic approach.

Another example:

Hi to all of you,

and first of all a great THANK YOU! With your input, i really have the feeling, as if i can manage to get that thing done!

@Michael: You are right, that thing is there already as a polygon modell, and the model included in the file is a "rough" version for
tracing purposes. In fact, i am quite good in polygon modelling- The piece here is something, which is going to be produced.
The company which we want to do the production asked for a STEP file and a NURBS model for doing the cost estimate.
Besides that i considered the whole thing a good occasion to learn NURBS modeling, which is with MOI a pleasure. Your
mentioning of T-Splines is interesting, because i am monitoring these for quite some time, but was not able to raise the funds
to get them (Besides they are Autodesk now, which is a company i am not too fond of). But while we are at it, i like
the concept of the T-Splines, and I belive it is inspired by the patch modelling of Animation:Master which has a spline
based modelling, which is on a certain level very much like NURBS modelling, but much more flexible. Just look at this
video:

http://www.youtube.com/watch?v=pX3mlGMCagU

At 01:00 or so, they demonstrate the patch/spline functionality. MOI already rocks, but if you could add functionality like that,
and make it possible that the results are solids, you will surpasss T-Splines by far!


@K4IY Mike: Thank you so much for your effords, and it seems as if your last suggestion (the boolean approach) is
the one which gets close enough to the desired solution. One more question: The two stumps at the origin of the "claws"
are curves which can be used in a sweep or a cureve network for constructing the claws onto the base?

@ to the rest of you all: Thank you so much for your support, i hope i can return the favour one day!
Best regards
Heiner

Great deal, Heiner!

>The two stumps at the origin of the "claws"
are curves which can be used in a sweep or a cureve network for constructing the claws onto the base?

I believe so, any edge of any surface should have useable curves.

You could sweep those curves further, or even use Blend to create 'transitional' surface patches to existing claw shapes.

The best course may be to consider the whole object when forming the surfaces that make up the overall curved shape.

Maybe at least with the larger of the two claws, you would have carried the main top and bottom surfaces through the whole course, then worried about the smaller one later.


This way, the overall feel of the shape would be continuous.

Hi Heiner,

> At 01:00 or so, they demonstrate the patch/spline functionality. MOI
> already rocks, but if you could add functionality like that,
> and make it possible that the results are solids, you will surpasss
> T-Splines by far!

In the future I'd like to experiment in that direction, but point cage manipulation and sub-d type tools use a much different toolset than NURBS modeling, and there is still quite a bit of work that I have left to do to improve things just in the area of NURBS modeling alone...

There are already a lot of tools out there for doing sub-d modeling and so that also means that it kind of makes more sense for me to focus in somewhat different areas rather than just trying to do the same as sub-d modeling, if MoI just gave you the same tools that you already have, it wouldn't really be giving the same kind of value- it's more when a tool does something that was very difficult to do in your other tools that it becomes more valuable.

It looks like Mike's approach focusing more on building the body and the arms separately and using more 2D curve techniques for cutting the body is a good way to go.

Basically NURBS modeling is strongest in the area of using 2D curves to build your model - if you're finding yourself doing all swoopy 3D curves all over the place usually that's a sign that you're trying to use polygon modeling techniques instead of really driving things by 2D profile curves which is where NURBS is best at.

Sometimes it takes a while to get used to using 2D curves in your workflow also as cutting profiles, a lot of polygon modelers are so used to forming everything directly by points, but instead in NURBS modeling you often want to build a base shape that is initially extended larger than your final one but then form some of the final areas by cutting that shape with 2D profiles, rather than trying to draw in all 3D profile curves all over the place.

- Michael

Hi Heiner,

** Your mentioning of T-Splines is interesting, because i am monitoring these for quite some time, but was not able to raise the funds
to get them (Besides they are Autodesk now, which is a company i am not too fond of). **

Clayoo is supposed to be very similar to how T-Splines works, but without the Autodesk association.

http://www.clayoo.com/


HTH, Colin

Hi Mike,

i was working on the model yesterday, trying to apply your workflow.
Basicly it works fin, but i can not figure out, how you get the slope applied
to the top surface?
Can you explain that a bit more in detail?
Thanks
Heiner

Hi Heiner,

Moi3D makes curved surfaces easy!

One way is to draw a curve in one of the side views, then use the Extrude tool make the curved surface.



You can of course add or move the control points during this process.




Now if you want to get really fancy, you can make a surface that has a more complicated curviness to it in all directions.

You'll need a simple set of curves, roughly placed together to form a framework.

You can draw them in multiple views, and then adjust the control points of each curve to represent the form in any particular area you wish.

The number of points can vary just as the curviness.



Use the Network command to make a new surface that has a curving form in all dimensions.



And now you can go further and actually manipulate the control point grid within your new network surface to add protuberances!


In my example earlier, I simply used a basic surface Extruded from one curve, but the process can be scaled.