BILT Speaker

BILT Speaker
RevitCat - Revit Consultant

Saturday 18 July 2015

Unable to Create Form Element in Revit Massing Environment


Unable to Create Form Element

No doubt anyone who has worked in the Revit Adaptive or Conceptual Massing Environment (CME) has encountered this hated error message, that simply 'cannot be ignored'?

I have recently been the victim of several variations on this error message, some of which were quite puzzling, and even had disastrous results.   Here is a typical scenario of when it might happen, and the sequence of dialog boxes:

Create a framework for a swept blend using profiles on a sweep path
 Refer to 'Creating Swept blends with adaptive profile' and 'Creating Hollow Sweeps' for more details on how to do this:
  • Create a spline in the adaptive/massing environment (external family, or in-place mass family)
  • The spline (or other path) needs to have a fairly tight angle change or else turn through more than 180 degrees over its length in order to demonstrate this issue.
  • Host several points on the spline;   
  • host a profile on the workplane of each point
  • Select each profile component and 'Create Form'
  • Depending on the relationship between the profiles, it might create a lofted form (swept blend), or most likely it will give the following message:
Self-Intersecting Geometry Error
  •  If you click on the 'Expand' button, it tells you nothing except the ID of the form that it cannot create.  
  • It gives you the option to 'Delete Instance', which is not helpful either, as it cannot create the form that it is offering to delete.
  • Try clicking on the 'Show' button and it leads to another series of useless dialog boxes:
  • Click OK to continue
  • Well of course it cannot find a view that shows the form with that ID - because it cannot create the form so it does not exist!  Yes it is sort of consistent with other Revit warnings where it occasionally can find a view showing the offending element - but in this case it is a pointless workflow, and it should not offer us the false hope of showing something it cannot show.

Here is another variation on the error message:
In this case it does not give you any clues about the problem (not even self-intersecting geometry).  At least the Show button is greyed out, because Revit knows it is pointless to try that option.  
No doubt there are plenty of situations where this particular error message might occur, but one I know of is when your profiles have loops inside them - refer to the hollow sweeps post for a solution. 

 (Partial) Solution

Those of you who have some experience with lofting or swept blends in the Massing environment might have already figured out how to solve this issue:
You might have picked up that I only suggested selecting the profiles before create form, but did not include a sweep path - congratulations to those who knew that one.  So, you need to pick the profiles, and the spline (or whatever path) before attempting to create a form.  Revit will then have a much better chance of figuring out what you want to achieve.

However, it still may not work.  In some situations you may not actually want the host framework to dictate the exact form - sometimes you want Revit to directly interpolate between the profiles, which may give a different result.

More on how to achieve this in the next post . . . .

Reorder Profiles Button

  • When creating a form you might be lucky and get a bonus message that seems to offer you a way out:
  • What or where is the 'Reorder Profiles' Button?
  • I spent hours (days, weeks, . . . .) searching for this function in the ribbon, on options bar, in the pantry, under the bed . . . . .
  • Eventually I figured out that someone at Autodesk must have planned to put in a functionality whereby Revit could analyse the order that each of the selected profiles might be changed such that it could actually build the form without self-intersecting geometry - sadly the functionality never eventuated but the dialog message was left hidden in the software. 
  • This functionality does actually exist in some other 3D applications - but not in Revit. . . . .
  • Then one day a few weeks ago, I got this slight variation on the dialog box:
  • Wow - so there is the 'Reorder Profiles' Button:  on the actual dialog box.
  • So, of course I did as I was told, and clicked on it.
  • Bang! Revit imploded and shut down quicker than you can imagine.  No chance to save the files or anything like that.
  • I am not 100% sure about this but it seemed like it actually deleted the Revit file from my hard disk - I can't be certain but I thought I had previously done a 'Save As', and there was no sign of the saved as file.  Maybe we can put that down to the fallibility of human memory?
The moral of the tale is:  If you ever see that 'Reorder Profiles' button, make sure you have a backup of the file before you try it out!

Unable to Create Form Elephant

If you ever see this error message, you are in serious trouble.  But don't worry, all you need to do is to get Marcello Sgambelluri to help out . . . . .

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