How to get faces of Joined Element?

[Anonymous]

Hi, I need to get a surface of element.

It is easy to get a faces of element.(element -> solid -> faces)

But I want to get a exposed face. It means the face except merged part.

I attach pictures for your understanding.

For example, I need exposed face of selected element. 

Exposed faces are like below picture. I fill in walls for faces.

I want to get faces exposed in air like picture.

In my case, I make elements to parts and merge these parts.

From these merged parts, I get a exposed face, like any element.(part -> solid -> faces)

But this method has many problem. So I need another method.

please tell me about your any idea.

thank you.

[Admin.CTI]

I have the same question, has anyone find an answer?

[jeremytammik]

You might try using the Face.IsElementGeometry property:

https://www.revitapidocs.com/2020/be3ad18d-a9d3-25ed-6200-4f71d3cd4754.htm

It indicates whether this geometry is obtained directly from an Element.

Maybe that means that it is the exposed face, whereas the unexposed face is generated by a join with some other element.

Alternatively, with more effort and less dependence on Revit idiosyncrasies, you can simply query the element you are interested in for all of its geometry faces. Then, grab all the neighbouring elements' faces as well. Determine and remove all the overlaps. What remains are the exposed faces.

[Admin.CTI]

Thanks for such a fast anwswer. I tried what you proppose, but all the faces of the element give true to this parameter, both the original faces and the faces created by joining with another element. 

[jeremytammik]

Thank you for your appreciation.

Yes.

Sorry, I am not surprised.

However, my second suggestion is meant seriously and guaranteed to work.

To implement it, you will need to identify overlapping faces in 3D, project them into 2D, and calculate Booleans intersections between them.

[RPTHOMAS108]

Join with slab, hide the slab extract the geometry by referencing the view with slabs hidden. 

Ends of beams would need to be full depth but could easily make those adjustments by checking if the end of a beam coincides with a slab edge.

I've not tested this but I recall the following historic documentation:

However bearing in mind join order. We have this old problem with Revit and integrated pile caps for example. Depending on join order the volume of cap is either the whole cap from top of slab to underside of cap or only the cap volume below the slab it is merged with. You also get double quantities when the cap isn't joined with the slab at all.