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.

Hi d3,

> Can I join all in one time or do I have to go thru all one by one?

You can join a bunch all at once, just select everything that you want and run Join.

Edges have to be close enough together to be joined though, at a regular scale level the edges should be no further than 0.005 units apart in order for them to be joinable.

- Michael

Shades V10 looks good but isn't this a poly modeler? I'm not a poly expert but in most poly modelers if you model using splines doesn't the surface update when you tweak the spline around?

-

Hi d3,

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

You mean have solids and surfaces automatically drawn in different colors?

No, there isn't anything for that because colors are already used for something different - you can apply Styles to objects so you can make visually distinctive groups for organizing your model and also set up materials to be used when exporting to a rendering program.

If objects were colored only by whether they were a solid or a surface, that would be in conflict with using colors for the style system where you are free to apply styles as you wish.

But a quick way to see if you are working with a solid or a surface is to select it and then look at its type indicator in the Properties panel in the upper right area of the window, here:



That will say "Solid" there if the selected object is a closed solid, or "Joined srf" if it is not a solid and made up of more than 1 surface joined together, or "Surface" if it is not a solid and just a single surface.

You can also use the Scene browser to select all solids, or hide solids, show only solids, etc... - to do that go to the Scene browser Types section here:



Click on the text that says "Solids" to select all solids, they will then be highlighted in yellow. Click on the eye to hide all solids, or right-click on the eye to hide everything else and only leave solids visible.

Also if you really really want different colors for solids and surfaces you can get that by selecting stuff with the scene browser there and then assigning a style. Like select all solids, and assign them Style = Orange, now your solids are displayed in orange.

- Michael

Hi Roger,

> 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.

Yeah in this case it would be hard to do a boolean since the indented part is so smooth with the neck, it's not a distinct enough part.

But that basically puts it into a more difficult/finicky/advanced type area of surface modeling with continuity...

That's just not really a fully implemented area in MoI yet, there's some beginnings of it but I think in v3 it should make some good progress.

One reason why I have not focused on that area so far is that I kind of expect that style of modeling to be done with a sub-d type tool instead of MoI - I've kind of put more focus on the solid modeling tools early on since those tend to be easier to use, quicker to learn, and also actually leverage more of the strengths of NURBS modeling and are more in contrast to things like sub-d tools.


> 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 have a vague memory of something I think was called Pixel3D, could that be it?

- Michael

Hi Michael,

I understand what you're saying. Sub-D's are fine for continuity but not so easy when integrating into the cad world. I often get requests from my client for STEP of SAT files from bottles I've built using Sub-d's and I have to either go down the T-Slines route, which makes for mega heavy patch meshes, or completely rebuild in Nurbs. This is why I'm trying to lean more towards MOI/Rhino from the start so I can have less rebuilding to do. It's all good fun really!

The modeller with splines was definitely shade. See here:

http://en.wikipedia.org/wiki/Shade_3D

Only poly based though so no good for me either!

cheers
Roger

Hi Roger, have you actually run into difficulty with a T-splines model that was just exported as a set of NURBS patches not being acceptable because it made a really large file or something?

I mean, that is actually the main focus of T-splines, to give a sub-d workflow but make a NURBS result...

Did you maybe get something like a client that considered the t-splines output to be unacceptable because it was different from the kind of structure that they were used to?


But yeah if you want to have a final output that is structured like a more typical CAD model, then building it in NURBS from the start would help get you that result... But also for really sculptured / non-2d-profile stuff it will mean operating with a more advanced (and difficult to use, and sometimes kind of headache inducing) kind of toolset instead of the simple solid modeling toolset.

The one you have here is actually not bad at all, but if you start to have broader pieces of the model that you're trying to surface in that way with multiple simultaneous transitions and branching type stuff, all while maintaining high continuity, that's when sub-d/t-splines starts to really become a lot more efficient.

- Michael