Solid union problem: "1. Boolean Union set is empty."

[Vigardo]

Dear experts,

I can´t merge several Breps. The Solid Union component dumps this error: “1. Boolean Union set is empty.”. Please, would you help me?

As you can check in the image, the Breps set exist. In the file UnionProblem.gh (89.9 KB), you can play with the slider to see that the Breps seem ok (the blue shapes). I also tried to flatten the set without any success.

Several threads here indicate that there must be some problem with overlapping faces or surfaces when performing boolean operations, but this seems not to be the problem since I succeeded in merging several boxes with overlapping faces in this simple test case: BoxesUnion.gh (19.3 KB).

Using meshes is not a solution for my particular case, as it is indicated here:

Joining a list of numerous Closed Breps doesn't work

[image] Thanks for your help, but the BooleanUnion is returning Null (the help for the fonction mentions that it’s supposed to merge surfaces, not breps.) Is that what you meant? Edit: I tried the second method: i converted the breps in meshes, and used the same plugin as you to join them and weld vertices. Problem is, the result is still a big mesh with a lot of faces and points on the inside. I’d like to get a mesh, brep or surface that is the outer enveloppe of the stack of cubes. Sorry…

I´m really lost here…

[Jakinta (Jasmin Cubic)]

In your particular case this can work, not general solution…

or like this with Anemone sequential “unioning” (i had in mind a case with random ordering)

UnionProblem_RE.gh (152.5 KB)

[Vigardo]

Hi Jakinta, thank you very much for your instantaneous workarounds!!

They work, but I can´t understand why just changing the Union order solved this issue. Would you explain?

PS: I generated the “sectors” with Convex Hull 3D.

[Jakinta (Jasmin Cubic)]

In 1st case i was looking for minimum overlapping, but I am not very sure how to explain in words why Solid Union operation is so unpredictable. Probably somebody else on forum can do it.
From my experience, whenever i had trouble Anemone sequential approach did the job. As long as Breps are correctly ordered, meaning that every sequential pair is touching, so the chain is not broken.