Creating form by ellipses not working properly


Long story short: the point at parameter 0 of each ellipse turns 90 degrees when the radius of one axis exceeds the other one. Why is this happening and how to solve this? Because when I try to make a form out of the sections in mass family, they twist where the start point of ellipse turns 90 degrees…



@Marcel_Rijsmus The end goal is to make a sections with which I can create a form in mass family. Just getting aligned points doesn’t help.


Maybe i did not understand you question. sorry
just a little tip here
if you want to get rid of the seams in your Conceptual Mass family, put a little void in it where you can’t see it.


I don’t really understand what exactly you’re proposing but what I want to know en resolve is the following. At the blue ellipse is the x-radius is smaller than y-radius, as soon as the x-radius exceeds the y-radius, the ellipse rotates 90 (red ellipse). So if I make a reference line from these two in an mass family and create form from them, it looks like this (twisted shape op image). How can I counteract that? I’ve tried rotating ellipses but it didn’t worked…


@fluffyhugger you want this?


Correct, but not with Dynamo geometry… :sweat_smile:

Curves from Dynamo geometry (NURBS of just curves) do not translate into closed curves in Revit. Because there are none from what I know. So ellipses it is. But when I try do make them from Dynamo ellipses to Revit model/reference curves than that bug with a twist happens…


Can you let me know what your plan is with this shape?
I think you can make a family from the solid directly.


Try segmenting each of the curves at the ideal start point.


@Marcel_Rijsmus Standard thing like cross sections with dimensioning, correct hatching, volumes, reinforcement etc.
@JacobSmall I don’t really follow… how do you mean?


Put a plane at 0,0,0 with the normal along the C axis. It will intersect all of the elipses twice on the Y axis. Use that as a tool to split the ellipse. This will allow you to bring the geometry over as lines for use in let’s say Revit’s massing environment, and should prevent the twist as all curves have an aligned start and end point.

I believe that Marcel was indicating to use something like a FamilyInstance.ByGeometry node or similar to turn the shape into a Revit element directly. This will reduce the flexibility to edit in some cases, but it should work for static or Dynamo driven updates that leverage element binding.


Thank you! That did the trick!

@Marcel_Rijsmus @JacobSmall I’ve learned that it’s better to not use the native dynamo geometry in Revit through FamilyInstance of DirectShape because you can’t do a lot with it if you don’t have the scripts or knowledge of how to use them.