Subregion creation question

[Anonymous]

I am getting the  "The constraints of the sketch...cannot be satisfied." error when trying to create a site subregion.  The model contains only the topo surface; no pads or other subregions.  The sketch lines I am using are closed and complete, as they are the same lines used to successfully create a floor slab.  I am copy and pasting the exact same closed sketch lines used for the floor slab into the subregion editor.   But the subregion editor cannot parse them.  

I think I understand why this may be happening and but wanted some feedback.  Basically as I understand it, a subregion is a calculation of a two dimensional shape intersecting a mesh(topo surface).  It is "cutting" through a topo surface mesh and creating another mesh at its intersection.  Therefore, tessellation values would be a factor, especially on curves.  And I understand currently, Revit does not allow any overlapping subregions (even though I have none in this example)

Even though the exact same group of lines that create the flat floor slab are being used, they may not work when creating a three dimensional subregion. Is this due to tessellation limitations of creating this new topo mesh?  And if so, is there a way to "clean" the slab linework so I can use it as sub region linework without the errors?  And also, is there a better way to understand what part of the sketch lines may be preventing the subregion mesh from being created?  The error message orange highlights the entire sketch linework, not specific areas.

[syman2000]

Do you have any overlapping lines in the sketch? I notice if you use civil drawing and pick their DWG outline, 99% of the time it won't be connected. So you have to use trim and join two lines together to make sure it is closed.

[Anonymous]

Hi, thanks for responding. The lines I am using are being copied from closed lines used to create a floor slab. So, the lines are clean and completely closed without error.

[barthbradley]

I'm curious to know if you can create another floor using the exact same sketch line work.  I'm betting not.  

[syman2000]

I've used this method before and it does cause some issue. My work around would be to copy the floor outline. Finish the slab without saving and paste the outline on the plan. It will create model line. Then copy the model line and paste it into topo subregion.

[Anonymous]

@barthbradley , I am able to the create a floor slab using the same linework.  You have lost this bet. 😉

[barthbradley]

AARGH! 

[Anonymous]

@Anonymous, lol.  I think that although the sketch linework can work for a slab, the concept of using linework for the subregion is affected by the complexity of the mesh geometry of the topo surface.  Meaning, that Revit needs to create a series of triangular vertices to make the same shape on a three dimensional mesh and can fail at doing this with certain linework.  I would like the team to perhaps implement a way to see where the subregion creation has failed more specifically, meaning instead of highlighting the ENTIRE group of lines, highlight a more focused area similar to the way Revit highlights an incomplete non-closed group of lines.

[Anonymous]

Whats amazing is that during the command the subregion is being created, see picture.  I can rotate the model and it shows the created subregion in orange.  I just cannot complete the command.  Do sub regions have interacting constraints from other entities in a Revit model that would impede its creation?

[ToanDN]

Share the file.

[Anonymous]

Ok, good idea will do.  Let me clean up the file and post.

[Anonymous]

Attached is the file we are experiencing the sub region creation issue.  The site mesh has a single subregion based on closed floor slab sketch linework.  I have this floor slab colored Red and set 1000' above (not elevation, plan wise) the site mesh.  We are trying to update the sub-region sketch linework with the floor slab line work, but it does not complete due to the error.  We are editing the subregion linework by deleting the linework in the editor and pasting the floor slab linework in the new subregion editor.  Since this linework can be used to create a slab, we thought we could use the same linework to create a site subregion, but cannot. 

The error prompt highlights the entire subregion in orange as the error, not a specific part of it, so its hard to tell where the failure is happening. 

Also, you can rotate the site mesh model mid-command which actually shows the subregion successfully created highlighted in orange, but you cannot close out the command.  This is why I think its actually successfully creating the intersecting mesh model, but something else is holding up the completion of the Revit command.