Hello, I have a group type loaded into Revit project, I use “add model group” to place multiple instances of this group into the model. Different locations and rotations (using rotated XY planes) is not a problem. Problem emerges when I try to place instance that is mirrored. To do that I have tried flipping axis of a plane that goes into “Point” input of the component. When I do that I get the error: “Element cannot be mirrored or rotated in a manner that changes its angle relative to the ground”. If I mirror same group instance inside revit everything works fine. Is there a way to place group instances mirrored?
Can attach the sample files ?
Have you also tried Element Location component? the location input can be point or a flip plane.
Hello Muhammad, thank you for reaching out. I followed your suggestion and tried using “Element Location” but when trying to set a flipped plane I get the same error (see image attached).
I also attach two files - Revit with two groups and a script where you can switch between not flipped and flipped planes when placing Group Instances.
Groups contain couple of walls, rooms and a floor.
Please let me know if you found a way how to deal with that
MirrorTest-GROUPS_forums.rvt (14.9 MB)
MirrorTest-GROUPS.gh (13.6 KB)
Hi @WR_QU
I am unbale to open the file. I think you are using Rvt 2026.
Muhammad, yes it was created in 2026. Which version are you using?
I am using 2025.4
I am sorry for getting back late, I needed to find someone in the office with this version. Below I upload the 2025.4 revit file together with RiR grasshopper script:
Mirror_test_group_forums.rvt (10.1 MB)
MirrorTest-GROUPS.gh (13.6 KB)
Is this what you were expecting.
I did get the same error but the component automatically removed it upon second run.
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@WR_QU, I believe that’s because of walls as they vertical elements constrained by the level and cannot be flipped or mirrored in a way that would change their angle relative to the horizontal ground plane.
I did a small test to check. its working for other groups as expected
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Thank you for your tests and reply. That is a bit surprising for me - I can very easily mirror the same group in native Revit (MM or DM) without any errors, but when I try to place a mirrored group via RiR I get the error.
Yes you are right it works in Revit. Let me check it again if we have any information available in API
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Sorry, I missed this post. What you showed in the first picture is exactly what I was after. I cannot get there no matter how many times I run the definition (always same error). Is there any specific order of things I should do to get there (other than recompute)?
nothing it just change the view from 3d to plan view
@WR_QU There is some issue with this model group. I would recommend rotating the model group instead of just flipping the plane.
Unfortunately, I need it mirrored, not rotated. These are just basic revit elements inside the group, nothing special. Thank you for trying to help though. @Japhy maybe you would be able to help here?
Would that be ok if we mirror the group using after placing them.
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Muhammad, I wanted to omit mirroring after placing groups but that will work. Thank you once again
I am trying to mirror a group containing stairs. Am I interpreting this correctly that the process involves placing another instance of the model group at the mirrored location, then using the python script to mirror the group instance?
Thanks.
You can simply select the element and provide the mirror plane.
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