Full Version: Polygon to Moi what are some best practices?

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Good day...
When exporting from Polygon to Moi3d what should I look for to get the best results?
What settings to use?

Thanks!

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Hi Matadem, for the general case the best practice is to not try to import polygon mesh data into Moi.

Usually polygon mesh data is best handled in a polygon mesh editing program and not in a CAD program.

The main exception to that is if you have a mesh configured for having sub-d smoothing applied to it. In this case you can export the subd control cage and convert it into a smooth surface in Moi using SubD > Create > From file.

So there isn't exactly a single answer that fits all polygon meshes, it can depend on the particular characteristics of the mesh.

A mesh from a 3d scanner with 10 million triangles is a lot different than a sparse all quad sub-d model control cage.

Do you maybe have an example mesh that is representative of the type of thing you would like to convert?

- Michael

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And there are often some defaults and / or errors in the original polygon mesh...
So you can use the free MeshMixer for repair it automatically!

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Good day...
Looking to do something like this

He is making the robot shield in Nvil and then to Moi for further details...
https://www.youtube.com/watch?v=ZjU31ij6BzA&t=1h04m28s

In Moi https://www.youtube.com/watch?v=ZjU31ij6BzA&t=2h07m47s

Thank you!

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Hi Matadem, so it looks like that is using the sub-d method.

For that method after modeling the sub-d mesh you would save it to an .obj file and them you can convert it into Moi surfaces by using SubD > Create > "From file".

Some info here on how the sub-d model should be configured:

https://www.engineering.com/what-is-subd-modeling/
https://www.flyingshapes.com/designing-with-subd
https://www.youtube.com/watch?v=ckOTl2GcS-E&t=126s

- Michael

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Hello,

About this video with pieces coming from NVil and refined in MOI : what is the MOI feature used to align the small circular parts to the surface of the face, at 2h08 ? I just tried Orient (for the first time), but I can't seem to figure out how it operates.

Thanks !

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“”””””” what is the MOI feature used to align the small circular parts to the surface of the face, at 2h08”””””

PastePart

If you want to kit bash, you can setup the part on 0,0,0 then copy it with Ctrl+C

Then pastePart as you describe.

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Hi Pior,

re:
> what is the MOI feature used to align the small circular parts to the surface of the face, at 2h08 ?

One of: Orient ( if object is in the same file), PastePart ( Ctrl+Shift+V if object in clipboard ), or ImportPart ( Right click File > Export if object is in its own separate file).

There's some more info on Orient here:
http://moi3d.com/4.0/docs/moi_command_reference8.htm#orient
http://moi3d.com/forum/index.php?webtag=MOI&msg=3424.13
http://moi3d.com/forum/index.php?webtag=MOI&msg=3424.14

- Michael

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Excellent, thank you both !

I was confused by the order of operations of Orient, but the way PastePart skips the setup of the pasted element (inferring it from 0 0 0) clarified it. I now understand the first steps of Orient.

This is a very powerful workflow, partly bypassing the need to reorient the Cplane in case of freeform modeling. Very nice !

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Maybe also sometime verify if the size of the import parts is at the good scale...
Depending of the progs used...

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Another question...what about if it is not a sub D object?
Like just polygons and I want to bring it into Moi for let say Boolean operations?

Should it go thru meshmixer like Pilou indicated?

Tnx!

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You have also the Obj23dmWireframe
http://moi3d.com/download/Obj23dmWireframe.zip

then you planar any selection you want...

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Hi Matadem,

re:
> Another question...what about if it is not a sub D object?
> Like just polygons and I want to bring it into Moi for let say Boolean operations?
>
> Should it go thru meshmixer like Pilou indicated?

For non sub-D meshes, I would recommend to not try to import that type of data into MoI.

Generally it's better to edit polygon mesh data in a poly modeling program, not in MoI.

There may be exceptions for specific types of models, it would help if you would give an example file.

- Michael

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Not to hijack a thread, but I often find myself needing to import a polygon mesh into MoI just to use as a 3D reference. I'm often given 3D files by clients that I need to make a part to fit accurately in MoI, or to remodel the whole thing as NURBS, and currently there's no easy way to do this. It would be great for me if I could just import a polygon mesh even as a pretty much un-editable, otherwise useless object, just to use as a 3D reference for remodelling. There's only so much you can do (and so much accuracy you can achieve) with screenshots from each side, or extracted 2D curves imported from a polygon modelling software

Or I've modelled 2 parts of an object, one in Blender and one in MoI, that need to fit together and I just need to check fitment and scale etc

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Hi DanC, for use as a visual reference you can use the OBJ23dmWireframe converter utility program, from here:

https://moi3d.com/wiki/Resources#Obj23dmWireframe_converter

That will convert an .obj file containing polygon mesh data into a wireframe .3dm file which can then be opened by MoI.

- Michael

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Good day..
I am working on something like this...not sub d
I was thinking of importing and perform exact booleans in Moi

I am still getting used to this kind of modeling...

Image Attachments:
demo.JPG 

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Hi Matadem, if that's not sub-d then I would not recommend trying to bring it into MOI.

Your model data will be made up of a lot of little planar fragments.

If you then apply exact booleans your result will be a weird mix of a faceted main body and smooth only on the cuts you apply in MOI.

The main way that it could work would be if you constructed the body as a sub-d model in your poly modeling program. Then the main body would be a smooth surface in MoI after you convert it from sub-d.

- Michael

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Understood.

Thanks!

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Thank you Michael, I'll check out that converter

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For future reference and if I am not mistaken, here are the commands (some custom/third party) used in that video :

- "_importobj" (third party) to bring in a .obj control cage without subdivision. If it fails because of unsupported geo, subdividing the object once before import can bypass the issue.
- "_Subdiv_beta9" (also third party) to control the smoothness of subdivision
- "ImportSubD" (stock) to import a .obj with subdivision and reconstructed surfaces
- "pastepart" (stock) to place parts on surfaces.

For the third party import and subdivision scripts : https://moi3d.com/wiki/MaxScriptArchive

I hope this helps !

Image Attachments:
_importobj _subdiv_beta9 pastepart tests.png 

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