Don't you think 'Join' operation is quite necessary but really low-efficient?

[Anonymous]

Every time I finish my model, I will see lots of overlapping geometries (for example, beams-walls, beams-columns) which cause missing lines, overlapping faces. And I have to join them. In a small project, manually joining operation seems feasible. In a large project I have to use some automation methods powered by Dynamo scripts. However, the joining operation is horribly slow. In one of my large project, with 763 collisions of beam and wall, the automation method took me nearly 30 minutes to finish it.😥

And I found a Revit model without joining operation could cause several errors in quantity calculation. So once an architecture firm want to analyze something with quantity calculation in a large project. Should the firm waiting so long for a joined project?

I tried ArchiCAD several days before. And it just joined all the elements when I created them. And there wasn't any delay. So why is the join operation in Revit so slow? Is there any limit coming from software? And why Revit don't take care about a highly efficient joining method? (I know there's an option for auto joining, but it always cause problems and is recommended not to be uesd) 

[barthbradley]

You sound like an ArchiCAD troll.  😉

I used ArchiCAD once. Had diarrhea for a week afterwards.  

[Anonymous]

Nope. I've thought this problem for a long time. I posted my question here just because the Join operation in revit took me really a lot of time in my last project...nearly 20 hours in joining various elements with Dynamo. (only Revit 2021 provide Join node in Dynamo) And this was necessary because I needed the lineworks for my rendering. (It seems my workflow is not very appropriate) The 20 hours of joining puzzled me deeply😂. So I just wonder why the join operation is so slow in Revit. 

[Anonymous]

And how do project managers deal with this problem once they want calculate quantity? Joining elements for 20 hours or more?

[SteveKStafford]

It doesn't take long for Revit to join geometry between elements and once it is done it doesn't need to be done again unless the model is altered and it can't maintain the join condition. If you're writing your own Dynamo graphs do join elements then I'd start there. The techniques used might be inefficient or looping in such away that it can't break out. It might be attempting to join elements belonging to categories that can't join either.

[Mirko.Jurcevic]

The problem probably lies in your script which (I assume) tries to join everything with everything, if those can't be joined, move to the next etc. Time for this grows exponentially as your number of elements grow, for example:

Joining model of 2 floors and 4 walls will result in: n=2+4=6, n!/(n-2)! = 30 joins

Joining model of 4 floors and 16 walls will result in: n=4+16=20, n!/(n-2)! = 380 joins

Joining model of 16 floors and 100 walls will result in: n=16+100=116, n!/(n-2)! = 116 * 115 =  13340 joins!

That's why it takes so much time.

I suggest trying one of the join tools (Revit add-ins) on the same model to see the results:

https://apps.autodesk.com/RVT/en/List/Search?isAppSearch=True&searchboxstore=RVT&facet=&collection=&...

Good add-ins will look for "local" geometry inside one bounding box and do joins only there and move to the next one, making this whole process very fast.

[Anonymous]

Thanks for all the explanations. 😀I tested it for two times. Your thoughts may only demonstrate my first try.

In my first Dynamo scripts(Maybe the worst script in my joining workflow🤣), I simply put two lists containing all the walls and all the beams respectively.(Some beams were in the tower and not related to beams in the shopping center). Then the 'Join' node was switched to cross product mode. And it took me so many hours.

However, in my second workflow, I learned a method with collision detection. First I achieved the collision report about walls and beams. It told me how many walls and beams overlapped. Then I import the list via a collision report importing tool of Spring nodes. There were 763 overlapping parts in my model.(763 sublists containing a wall and a beam). I separated them into two lists and put them into joining node of Dynamo. It also took me nearly 30 minutes to join all the elements. On average, one joining operation cost 2-3 seconds. Although the automated workflow was much relaxing than joining them manually, the operation seemed still not efficient enough.