Full Version: import SubD with crossing creases - any solution?

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Even this always Blender (Blend) --> export OBj --> Native SubD / Create from file
no crease again!
https://moiscript.weebly.com/uploads/3/9/3/8/3938813/another_one.3dm

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Hi Tom,

re:
> I'll also attach the blender file and the obj.

One problem is your .obj contains a high poly already subdivided result with gaps in it, it looks like this when loaded into Cinema4D for example:



The .obj file format does not have any method in it for storing edge weighting, so it isn't possible to transfer your edge weighted model directly to another application using that file format.

In the future I do want to support FBX format transfer for the sub-d importer in addition to .obj format, and FBX does have a way to contain edge weights.

Currently you will need to use some other solution than MoI though.

- Michael

Image Attachments:
obj_already_subdivided.jpg 

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The File Blend exported in OBJ (from Blender) then Import by SubDIv / Create from a file don't resolve the problem ?

As Shown in my previous posts ?

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Hi Tom,

re:
> You may be right, but when I remove the modifier in Blender before export, I
> get a different mess, but not a better one...?

Can you post the .obj file that you generated for this one?

When you export to .obj, the .obj file does not contain any edge weighting, there is not any facility in the .obj file format itself to store edge weights.

So there is not a way to transfer an edge weighted model using this file format. The .obj file that you generate where the edge weights have been stripped out will not generate your same shape in any application. There isn't a way for the receiving application to automatically know what your edge weights are, they are effectively discarded during the .obj export.

- Michael

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Hi Micheal about the storing edges in file format you can add in the next release the ability to convert also FBX that has the feature to store edges creases? or maybe at latest the use of edges sharp as edges creases in OBJ that store that data?
Thanks :)

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Hi pafurijaz, there is not any method in OBJ format for storing edge weights. It's not part of the format spec. I do want to add support for FBX imports in the future though.

- Michael

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Hi Michael,

you guys were right, I did it wrong the first time, but like I wrote, the "correct" (?) way also creates a mesh that seems to need a lot of additional work with manual clipping (not in this simple example, but in the production object).

Pilou, thanks, but your version creates a mesh with tons of control points and is very hard to deal with in the further process - and also not what I need in this specific case.

As for the endless mantra of "obj does not contain crease information": There are many ways around that limitation.
Either one can use "sharp edges" like pafurijaz wrote, use a different file format or have an editor on import where the user can add the weights manually.
But what I get from this discussion is a basic non-understanding of SubD and it's benefits when fully implemented, or at least a very limited interest in it.
We had that same discussion several years ago and got to the same point.

That is fine with me.

It's also somehow funny, since I heard the same from Rhino (and other CAD-) people for ages while they fumble around with crazy complicated workflows to create simple organic shapes with NURBS and now in Version 7 they rave about how SubD is a major breakthrough and "changes the way you work".
Yes, indeed...
The CAD world is just about 10-20 years late as usual...
Maybe one day MoI will do the same as Rhino does now, implement SubD as a native object format.

I personally am the other way around, I find NURBS a kludge that I only use when I have to. They have some specific technical benefits, but also massive drawbacks for organic design.
But that's a whole other can of worms...

As you were,

Tom

Attachments:
SubD_OpenEdges3.obj

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Nice for fbx, about obj the file format doesn't store creases but what I mean is the use of edge sharp as a trick because OBJ store in it the normal information for the smoothness shading like this image below, is something assimilable for the creases information inside that anyway Moi3D doesn't use in importing process. As can see in the images below these edges on the model are marked only because they are marked in the obj file format.
Anyway that aren't the right way,is only a compromise.
Anyway I'm happy with new feature in Moi3D I have the ability to convert complex hull without much works already with the v4 Thanks!

Image Attachments:
Schermata del 2021-03-03 11-32-06.png  Schermata del 2021-03-03 11-32-29.png 

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HI Tom, ok but you are aware that MoI is a NURBS modeler, right? So that's what it is primarily focused on.

If you're not interested in NURBS modeling then I find it confusing why you are here.

Sub-D is definitely useful and has its place particularly for organic shapes but for example the shape you
posted earlier is very easily constructed using NURBS modeling:







The strong area of NURBS is with models that are well defined using 2D profile curves.With mechanical shapes
it's sub-d that becomes a horrible kludge, instead of just being able to drill a hole through something you have
to manage a sea of points and become an expert in topology. And even if you fight your way through all that at
the end you don't have any kind of precision control over how exact of a circle you've got. With NURBS you just
do this:




Sub-d has a significantly higher learning curve, it requires developing spatial awareness skills that are
more like sculpting and wrangling points in 3D space. Forming shapes from 2D profile curves in NURBS
modeling is significantly easier for people to learn when starting from scratch. That's the reason why MoI exists.


re:
> Maybe one day MoI will do the same as Rhino does now, implement SubD as a native object format.

Yes, that is something I'm slowly working towards. That's the reason why I added a SubD to NURBS converter
in for MoI v4, to open the door for a using a hybrid modeling approach using SubD to create some organic
elements like say the base form of a helmet and then continue working on it using the regular NURBS toolset
to construct other components from curves and add details using booleans.

The Sub-d converter is a step towards that, in the future I do expect to add some sub-d modeling tools directly
into MoI as well, at a kind of basic level for doing fairly lightweight base shapes.

- Michael

Image Attachments:
tom_nurbs1.jpg  tom_nurbs2.jpg  tom_nurbs3.jpg  tom_nurbs4.jpg 

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<<< like in Blender a weight per edge between 0.0 and 1.0 for in-between semi-sharpness).

Seems this "weight" is something in Nurbs variable fillets...

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What was the method used for the start volume ?

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Hi Pilou, I did an extrude followed by boolean intersection:







- Michael

Image Attachments:
pilou_shape1.jpg  pilou_shape2.jpg  pilou_shape3.jpg 

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Funny as the position of the vertical section changes the result!

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Michael wrote: "... open the door for a using a hybrid modeling approach using SubD to create some organic
elements like say the base form of a helmet and then continue working on it using the regular NURBS toolset
to construct other components from curves and add details using booleans."


Exactly. I'm working on my 3rd MoI car model tutorial at the moment. Built 100% within MoI. The car body is SubD, the interior is partial Sub D & partial Nurbs, and the wire spoke wheels and external chrome trim pieces & bumpers are Nurbs.

I like working within one program, and a hybrid approach works well for those times you need it. After seeing demos of the latest Rhino SubD tools, I considered buying Rhino for that purpose. Then I realized I don't need SubD for my business use, just my hobby use, so I decided against buying. So while the current SubD tool set is limited, you can do some very useful work.

My opinion is MoI has most the essential SubD tools and just a few more basic ones would make a very nice toolkit. As with any software, you'll want the high end complex packages if you're a professional, but MoI gets the job done for me.

Ed Ferguson

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Also for me Moi3D is sufficiently good if you know how use, the SubD, Moi3D gave me now the possibility to make complex hulls, that I can edit and make these better inside Moi3d in less time, but I have an experience in both type of software Nurbs CAD and mesh modelling such as sub-div software, I can also predict dimensions of surfaces also diameters and for me is a dream this bridge between these worlds not only for organics types, because often is very harder obtaining a Nurbs shapes with surface continuity in a CAD modeler.
these images are all converted from subdiv geometry, edited inside Moi3D in various mode with boolean and surfaces joined and made them solid.

Image Attachments:
Schermata del 2021-03-04 01-44-01.png  Schermata del 2021-03-04 01-45-01.png  tn.png 

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Hi pafurijaz,

I do agree at 200% but i'm really comfortable with my new workflow since 2 years now : Moi3D + Blender

Cheers

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