I think there are 2 true statements coming out of this discussion:
1. Revit's modeling tools have room for improvement (although they are getting better with each release). As the open API improves, plugins and third party applications might give some serious help to this end.
2. Complex form generation is almost certainly going to involve more than one program - this is true whether you're using Revit or not. Of equal importance to improving native modeling tools is improving interactivity with other modeling software.
Computer modeling always has hidden constraints, whether it's workplane based extrusions or SubDs. The trick is to know these constraints and use a suite of programs to either leverage or ignore them. Or, as was said above, write your own code.
PS-- one of the most important things about the form in questions is the lack of hard seams at the corners. This makes it a lot harder to model...
Last edited by bregnier; 2010-06-10 at 03:46 PM. Reason: added the ps
Using different software packages isn't the problem, especially when your doing competitions where you only have a few days or weeks to come up with a design. You're likely to use a tool like Maya or Rhino to knock out hundreds of different variations within minutes, before choosing one.
The questions is, what do you do when you have to document them? What are the steps you need to take to rationalize the geometry and make it workable in Revit? What added value can Revit bring to such a process? You can for instance model the Watercube in Beijing, but it will take you ages. So knowing when to make Revit part of the process is crucial, because Revit has it's limitations.
As for roof form, I think I would design it in another software package and try recreate it in Revit for documentation. It will be a challenge to get the exact dimension from the geometry that was created in another package. And while having a split surface isn't favorable, you need to make a chose where the surface breaks. The attachment is the same file as what Leo posted, but lofted differently. As you can see, you get a different shape from the same splines.
Revit in my mind acts as a coordinator, kind of a master database for the entire project. Really complex parts can be followed through in some other software, with the assembly as a whole represented in the Revit model (with approximate geometry). The Revit model is then responsible for locating the assembly and referencing any additional information.
I'm not saying that at some point we won't be working out of a single model for every last bit of information. But as it stands right now, doing so with _any_ single software would not be easy or efficient.
What I meant by getting the exact dimension from the geometry is to recreate it exactly the way you made in in Rhino or Maya. I've tried recreating geometry like that in Revit, but you'll never get it to look exactly the same way.
At the end, you will indeed use other software for shop drawings. However, it will then be hard to justify the use of Revit, since you go form an all purpose modeler or parametric modeler (Catia) straight to fabrication.
Catia would technically work for soup-to-nuts digital design, except for the enormous learning curve and inefficiencies that result from using a very powerful tool to do simple things. If you look at the workflows of offices using Digital Project oftentimes you'll see DP used on the most complicated part of the building and Revit (or even Autocad) used for the rest.
I wonder, in Leo's example, if adaptive components could be used to "smooth" out
the hard edges at the "corners" ?
I think Revit is getting very close to having the same modeling abilities as Rhino,
FormZ, etc--but with all the BIM as well--not too bad for an all-in-one package.
I agree that ultimately other packages will be used downstream to feed file geometry
to a CNC cutter or automated fab tool, so whether or not Revit "can do exactly what
XYZ software does" is not critical. The notion of Revit as a Master Coordination tool as stated in the previous post is very valid.
That said, I'd like to see Conceptual Massing tools have even more fluid workflow, and perhaps NURBS ability in future releases.
I would also like to see the option to "release" walls, roofs, floors, curtain systems, etc
which were created by picking Mass faces, so they are not prescriptively and permanently
tied to the Mass--but I know this idea flies in the face of the way the program was designed.
Cliff B. Collins, Registered Architect / BIM Specialist
St. Louis, MO
What a great idea for a thread, AP23! It deserves its own forum spot.
The British Museum roof form is largely a result of calculations done to reduce the variations in the panels that create it and it is, I think, entirely without seams. Here is another method to approximate it in Revit (video in the zip file, 40 second journal replay).
I've been having difficulties over the past few weeks in trying to get a 3 point ellipse sweep to work. Anyway, eventually I got it working. See attached:
It's a generic model nested into an Adaptive Component. I found the Ellipse tool worked a bit different in an adaptive component family in comparision to a standard Revit family.
Melbourne - Australia