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Thread: "Revit can't do that....." series part 1

  1. #11
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    Default Re: "Revit can't do that....." series part 1

    Quote Originally Posted by AP23 View Post
    I'll be posting in the coming weeks a few samples of geometry that is easy to create in other 3d software, but extremely difficult, if not impossible to do in Revit. These posts are not intended to bash Revit, but to discuss workarounds and discover new possibilities.

    First example: the glazed roof of Britisch Museum in London done by Foster and Partners.

    In Autocad (see attachment) or rhino, you can create this roof by lofting 3 profiles. Doing the same procedure in Revit will end up in an error. So you will need to move the inner profile above the second profile before moving the inner profile back to its original position. However, even so, you get an undesirable shape (see attachment).

    Anyone knows how to do this in 2 minutes?

    here is a pdf link to the roof structure http://opus.bath.ac.uk/14111/1/ChrisDeakin2001.pdf
    AP23,

    Here are my sample solution to your form problem.
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    Default Re: "Revit can't do that....." series part 1

    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

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    Default Re: "Revit can't do that....." series part 1

    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.
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    Default Re: "Revit can't do that....." series part 1

    Quote Originally Posted by AP23 View Post
    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.
    This sort of approach makes sense for certain kinds of construction - such as curved interior walls- , but for things as complex as the British Museum roof, or some sort of complex metal panel system, dimensional control in construction is likely going to be ceded to an entirely separate model, perhaps under the control of a consultant. In that case often the consultant takes a drawing set and some exported geometry and builds their own model that is used to generate g-code or cut lists. Even if you're doing it yourself it's usually easier to generate shops in another program.

    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.

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    Default Re: "Revit can't do that....." series part 1

    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.

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    Default Re: "Revit can't do that....." series part 1

    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.

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    Wink Re: "Revit can't do that....." series part 1

    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.

    cheers

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    Default Re: "Revit can't do that....." series part 1

    What a great idea for a thread, AP23! It deserves its own forum spot.

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    Default Re: "Revit can't do that....." series part 1

    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).
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    Default Re: "Revit can't do that....." series part 1

    Thanks Zach.
    That's cool.
    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.

    Brian
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