Hi Michael,

Here's a problem that's been driving me nuts. I lost most of yesterday trying to figure out how to do this in MOI, I'm sure there must be a nice elegant solution but I couldn't do it, although I have a cold so it's probably my brain that's at fault!

Here's a bit of a bottle I'm building for a client.




As you can see there's a 'flat' in the shoulder that allows the positioning of a round label. The round area is flat but has to blend smoothly up into the neck as the label hangs down kind of like a medal. Anyway, the blend up into the neck wasn't a problem. My difficulty was getting the edges indicated to blend smoothly into each other. Because glass can't form sharp edges the indents have to be 'soft' so I need to create a draft surface in there that's tangent to the flat and the shoulder of the bottle. Hmmm. I tried joining all the edges into two curves but they wouldn't blend together at all. I tried lofting but they wouldn't retain G2. I did manage to sweep a line around using the curves as rails but again, no G2, just sharp edges.
I can get it to work in Rhino at a push using 'Blend surface' with some added controls (see picture showing nice G2 blend)



but I'd really like to be able to do it in MOI because I just love working in it! It's running like a dream in Parallels as opposed to Rhino, which has awful mouse spin problems.
So, after all that ramble, can you think of any way of achieving this in MOI? I've attached the file.

Many thanks,
Roger

Further to those last pics, here are a couple of images showing a version made in modo and brought into MOI using T-Splines. It's not a very elegant mesh but I can't imagine how you'd make such beautiful curves and blends in a nurbs package. (or at least I couldn't). These are just to show what it should look like. I can't use them as they are way too 'heavy' for the client. Ho Hum...

Hi Roger, currently MoI's blend tool is not as sophisticated as Rhino's - MoI's is only set up to blend between 2 edges and won't really handle a "chain" of edges like you need for this case.

In some cases you may be able to split up edges into matching pairs to get the job done in MoI, but really your best bet for this would be to move your object over to Rhino (you can use Copy/Paste to do this quickly), do the blend in Rhino and then bring the blend back into MoI.

It won't be unusual for you to find instances like this right now especially when you are trying to work at a "surface modeling" level of building a patchwork of individual surfaces rather than using more of the solid modeling toolset.


I do plan on enhancing the blend tool in MoI in the future to handle this case, but you should generally keep in mind that Rhino has been around for a lot longer than MoI so some of the tools in Rhino have had longer to mature.

It's still fairly early in MoI's lifetime right now, so it will not be unusual to find things like you have in this case where you need to use an alternative tool like Rhino in combination with MoI.

As time goes on and MoI gets more mature and has more things filled out in different areas (like more continuity tools and a more refined Blend tool for this case), then there will be less and less of a need for that.

But right now I'd really recommend to make use of other tools that you have available to you particularly when it's for one surface or a specific task or something like that - just Copy and Paste, get the job done, then copy and paste back into MoI.

Particularly if you're trying to do tasks that are related to building surfaces in a "patchwork" type manner and you are focused on continuity issues, that's an area that is handled better in Rhino currently.

That does not mean that you can't use MoI for your project, you can still stay in MoI for much of the work and just move things into Rhino to accomplish some specific task and then come back into MoI.

If you're working more at the solids modeling level with things like cutting objects and doing boolean operations, that is more of the area where MoI has been focused more specifically on so far, because it generally makes things happen very quickly for simple kinds of objects. In your case here you are trying to use a much different kind of modeling technique than the solids modeling toolset though.

- Michael

Hi Roger,

> Further to those last pics, here are a couple of images showing
> a version made in modo and brought into MOI using T-Splines.

Yeah, there are definitely cases where a sub-d modeling toolset like you find in Modo or T-splines is easier for a particular case than a NURBS modeling toolset.

If you find yourself worrying a lot about continuity and trying to make a patchwork of surfaces smooth to one another, that's generally a sign that a sub-d modeling toolset could be a better fit for that particular model than a NURBS modeling toolset.

Really the area where a NURBS modeling toolset becomes particularly strong are when the models are well defined by profile curves so you can do things like cut a solid by a profile curve and shape your model by boolean combinations possibly followed by fillets rather than going in a "patch by patch" type approach like you were trying in this case.


But it is not unusual that certain kinds of models will be better for sub-d and that other kinds of models will be better for NURBS. There is not one single kind of modeling technology that is universally better for every single kind of modeling task. It sounds like that is kind of what you are hoping to find? But that is just not something that exists.

Maybe in your case here it would be possible to do more of a boolean + fillet approach instead though, I'll take a look at your model which I have not examined closely yet.

- Michael

Hi Roger
Hi Michael,

The task at hand is still achievable in MoI though, but with low level modeling techniques and about 15-20min work including a bit of model clean up, but as mentioned if you have the tools at hand to do it instantly, yeah, I'd be using them too until MoI catches up.

Cheers

Hi,

is the attached closely near what you asked?









Thanks,

-d3-

Hi Michael,
Thanks for the reply. I guess you're right that I should just use what I have to get the job done. I just wondered if I'd missed a function or something. And of course after working in MOI's lovely smoothness, going back into Rhino is just so clunky :-). Using Sub-d's is ok in certain circumstances but it's never ideal as you can't trust the dimensions of radii to be perfect or the circularity of circles like the indent here to be perfect. Sub-d's always distort the mesh a little, that's why I'm venturing into the nurbs universe in the first place.

I did have an idea while lying awake mulling this over last night: Assuming I've created a sharp loft between the existing curves, I could offset a nice rebuilt curve into the shoulder by 1mm, then offset same curve down the 'slope' surface by 1mm, tweaking the ends where the get closer to a point near the neck. Then I could trim away the surface between the new curves and blend a nice fillet between them. That may just work. I will give it a go tomorrow...

D3, Yes, that looks exactly like what I want. I will examine your model and try and work out how you did it. (any hints?). Thanks.

R

Hi,

I try to explane what I did later this evening.
(I started from top with blends and continued to first rounds then used guide lines and sweep and trim.)

For me it`s easier to explane with sample pictures.


Thanks,

-d3-

Here's a version where I used low level surface modeling tecniques like I mentioned before, I worked on one half of the bottle then mirrored it.
I basically seperated the model, lofted edge to edge and applied fillets, this included a bit of trimming here and there.

I did try the method d3 had posted but the area circled in the picture loses tangency to the ajoining surfaces and there were a few naked edges avoiding the bottle to become a solid.

Hi Danny,

That looks very nice! I tried to fillet my edges like that but they wouldn't work. I've had a close look at your version and I see you'v added a tiny edge where the fillet fades out. That's a good idea!
I'd never have thought of it. There does seem to be a slight kink if you zoom in super close to that tiny edge, but I suppose if the object type shows as 'solid' then it must be a watertight object.
I'm going to have a go at reproducing your version myself so I can see if I can get the same result.

Thanks for your help on this problem guy's. I'm learning new stuff all the time from this forum.

cheers
Roger

Hi Roger, also one thing you might try if you are having difficulty with filleting is to break the model into individual surfaces and then do some filleting by picking 2 surfaces at a time and running Fillet.

When you have 2 individual surfaces picked and you run Fillet, it does a somewhat different surface/surface fillet calculation which can sometimes avoid difficulties that the edge-based filleter can run into.

But the surface/surface filleter won't do things like build corner patches where multiple edges are coming together.

- Michael

How you turn surface to solid in MoI?
Ok,, the model have to be watertight, but after that?

Hi d3,

> How you turn surface to solid in MoI?
> Ok,, the model have to be watertight, but after that?

Use the Join command - once all edges of a model are joined to other edges forming a watertight closed skin, that makes the object enclose a volume and that is what makes a solid.

There is no difference between being watertight and being a solid - the way that CAD programs define a solid is by a watertight skin. This is called the Boundary Representation or B-Rep method of defining a solid, for more info see:
http://en.wikipedia.org/wiki/Boundary_representation

Often times people seem to think that there must be something else in addition to that, but that's not the case. Once something encloses a volume it can be used to define a solid where that volume is considered to be a filled region.

- Michael

Also, the model doesn't have to be water tight every time, it depends what you are going to do with the model, for most rendering programs a joined surface will be fine, but if want to output the model for manufacture like a into CAM package the model should preferably be a solid body or if it is just a joined surface it shouldn't have any tiny holes in the surface.

It's also quicker to model with solids in MoI, when using the boolean functions the model always stays a solid.
Working with low level modeling techniques, surface by surface, requires high accuracy and alot of practice, not only in modeling the surfaces but identifing why the model isn't a solid and knowing how to correct it.


-

All good and useful info. My problem with this model was that it couldn't be done using booleans. Because of the smooth transition from the curved neck into the flat indentation it had to be made from blended surfaces.
As Michael pointed out, the best method in the end was to break the area down into individual sections and blend them, then sweep the last bit where the profiles came together. Worked like a charm and looks lovely. As this model will be used for prototyping and not rendering it had to be solid. I did a purely sub-d version for the renders as accuracy wasn't necessary and uv-ing for texture maps was easier.

Back in the olden days, (maybe 15 yrs ago now) there used to be a modeller that used a kind of 3d version of bezier splines like illustrator. I think it was Electric Image or early Shade or somesuch. I remember you could edit the splines in 3d just like illustrator and it would constantly update a surface between them. It was very clever. So for a model like this you could literally draw the outline of the indent on the bottle surface and pull it down into it, creating the depth, all the time retaining the editing ability of the splines. No idea what happened to it though. That was back on a mac classic and long before iMac's etc.

I totally agree Roger, that's how I did that area, I broke it down into individual sheets and used filleting as Michael described previously.
I was tagging on Michaels answer to d3's question.
I try and work in solids as much as possible but some cases do require surfacing.


Cheers

@roj - the program you mentioned was Shade. It is still being produced today. I believe the current version is 10 in Japan, 9 in the US. If you're interested I got version 8.5 professional on a 3d world cover disk a few months ago. Let me find the info:

OK - the issue was number 123
you could buy it here: http://www.myfavouritemagazines.co.uk/store/displayitem.asp?sid=418&id=8991&custid=30@01@200958213@09319482

The one at the link is 8 to 10 pounds depending on where they're mailing it:

or I believe on ebay sometimes.

IHTH

"Use the Join command - once all edges of a model are joined to other edges forming a watertight closed skin, that makes the object enclose a volume and that is what makes a solid.
"


I`m not so familiar with surfaces, I have done lot`s of works with solid parts and assemblies so there are still a new area to learn :).
Can I join all in one time or do I have to go thru all one by one?

Thanks,

-d3-

Are there any options for surfaces and solid part colors?
It would be easier to see which part is in surface mode.

>>>>I remember you could edit the splines in 3d just like illustrator and it would constantly update a surface between them.>>>>>


MoI's history does this if the object hasnt been re-edited with another function yet. Look at the "6 legged pod" tutorial in the help or online to see it happen. :o

>>>>Are there any options for surfaces and solid part colors?>>>>>

Version 2 has this.