Full Version: Solid in 2 parts !

Hi everyone,

Look, a solid made up of two elements. It's a bit surprising.

It's double glazing for a window. It comes from a collective housing project I did with Revit (a long time ago!). I exported the Revit file to MoI and also to Blender.

Below is the .3dm file for the glazing.

Attachments:
Solid-in-2-parts.3dm

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Funny : if you separate then Boolean Union you obtain 2 solides!

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Well, apparently no one has an explanation. It will remain a mystery.

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Hi Zooen, that's called a "disjoint brep". Most commands where that could occur do some work to separate those into individual objects. You can do that to fix it by using Edit > Separate followed by Edit > Join.

To fix what happened in your particular case here I would need to repeat the steps that created it instead of only seeing the end result.

Do you remember what command you were using that produced it?

- Michael

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Bonjour Michael,

From Revit, I exported the 3D view of the completed building in .sat format. I chose this format because MoI 3D and Blender can import .sat files.

Then I looked at the window panes in the Blender file to apply a transparency property to them for rendering; and that's when I realized that the window panes were made up of two elements. Intrigued, I checked to see if the same thing happened in MoI 3D, and it turned out that it did, as you can see. That's it, nothing else.

For your information, many 3D building construction elements are created by manufacturers in DWG, DXF, RVT, etc. formats for use by architects, engineers, and building design office technicians. This is the case, among others, for the windows and French windows that I used.

It intrigues me, but it doesn't hinder my project.

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Probably have to do a bit of work in Revit first

Being a BIM modeler and app, things like these windows are setup as “Families” and various other elements that interact in IFC and shares with autocad and large scale projects.

Look at converting families to parts. Exporting the parts you want out. You woulnt want to start with exporting your “building” to look for good single working models all perfectly individualized components and parts. Probably run into lots of issues with stuff

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Hi Zooen, can you post the .sat file here or e-mail it to me at moi@moi3d.com?

But if Revit has created a single brep made up of disjoint faces, then MoI is just reading in what Revit has generated.

Since I'm not developing Revit I don't know why they would want that, you could ask them I guess?

What happens if you load the SAT back into Revit, is it separated there?

If you can send me the file I can see how some other programs interpret it.

- Michael

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For those following this post, I sent Michael the .sat file for one of the windows in the project, as well as the .rfa file created by the window manufacturer selected for the project.

Michael@ "But if Revit has created a single brep made up of disjoint faces, then MoI is just reading in what Revit has generated". Yes, I agree, that makes sense to me. But these are not disjoint FACES, it is a "double solid" of sorts.

If anyone knows how to make a "double solid" in MoI3D like the one I posted above, please explain to me how to do it. And I think Santa Claus will give him the gift of his dreams!

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Hi Zooen,

re:
> If anyone knows how to make a "double solid" in MoI3D like the one I posted
> above, please explain to me how to do it.

In most places where that could occur it gets broken up into separate objects.

But one way to do it currently is with the new move face, if you move a face far enough that it divides the solid into 2 pieces you will get a brep object with a disjoint shell:






Sometime soon I'll be fixing it up to separate those into 2 separate solids.

re:
> But these are not disjoint FACES, it is a "double solid" of sorts.

Yes actually it's called a "disjoint shell". In CAD topology there is usually a topological container called a "shell" that has a list of faces in it. There isn't anything about the topology's structure that ensures that all faces are connected to each other.

- Michael

Image Attachments:
zooen_disjoint1.jpg  zooen_disjoint2.jpg 

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Hi Michael,

Thank you for this information.

> But one way to do it currently is with the new move face, if you move a face far enough that it divides the solid into 2 pieces you will get a brep object with a disjoint shell:

I have not yet fully integrated these latest developments into my daily practice.

I think "le père Noël" will grant your wishes for Christmas! (Note: corrected on Larry's advice, read the following posts below)

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> I think Santa Claus will grant your wishes for next Christmas!

Aw, Zooen, I think he deserves to have his wishes granted THIS Christmas!! ;-}

And to the topic/question you raised, I think Michael's answer is both surprising and quite interesting. I really appreciate these little tidbits explaining the "why" of how things work!

--Larry

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Hi Larry,

Larry@ Aw, Zooen, I think he deserves to have his wishes granted THIS Christmas!!
Of course you're right. I'm on the old continent, and in my mind I was thinking of Father Christmas (translation error). Right, I'll quickly correct that (he's still asleep, le père Noël he's an old man, like me!!).

Larry@ And to the topic/question you raised, I think Michael's answer is both surprising and quite interesting.
I agree with you on that point. And above all, we must always remain curious.

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