Group A - BIM Tools and Parametric Modeling

In this blog post, chapter 2 of the BIM handbook is covered. This chapter talks comprehensively about BIM modeling and parametric modeling. It begins with the history of BIM modeling. Building modeling based on 3D design began in the late 1970's, and the systems were expensive, difficult to use, and often did not have access to the necessary computing power. As such, programs such as AutoCAD and Microstation were favored, and 2D design remained dominant in building design. In early BIM design, two methods of 3D design competed: B-rep and CSG. Both are now used today. 3D design was influenced by parametric modeling, which allows a designer to define elements or families that update themselves based on their context and given parameters. Rather than manually modify each shape, parametric modeling allows objects to update themselves as a designer changes a few parameters. After an in-depth look at the capabilities of parametric modeling, the chapter concludes with an overview of the major BIM modeling systems. It describes the strengths and weaknesses of programs such as Revit, Bentley Systems, ArchiCAD, Digital Project, Tekla, and DProfiler. All of these programs have various selling points and faults, and none are universally best for each project.

The shift to 3D and parametric modeling has made the design process easier and more efficient. I experienced how much easier it is to design in a 3D BIM Program as opposed to a traditional CAD program in my last co-op at EwingCole. EwingCole is still in a transitional period where both AutoCAD and Revit are used, depending on the project. Changes and revisions are common in a design firm, and the drafting changes that I was asked to make were always much easier to make using Revit. If a wall height was changed on a Revit project, it was a simple matter to select the wall, type in the new height, and allow the program to update the sections and change the heights of associated objects to compensate. If this same change was made on an AutoCAD project, it could mean an hour of work changing heights on a variety of sections and changing the heights of the other objects. Parametric modeling is much more efficient and allows drafters to make changes quickly and with fewer errors and oversights.

Comments:

Matt's blog (http://ae-510-ay13-14.blogspot.com/2014/01/bim-tools-and-parametric-modeling.html) touched on something that I didn't really consider in the amount of computing power necessary for these kinds of programs. It's easy to take for granted that a computer now can just do anything, but it must require huge amounts of processing power to automatically update hundreds or thousands of unique objects. It would be interesting to know if there are buildings or designs complex enough that normal computers can't handle them well.

Esther's blog (http://ae-510-ay13-14.blogspot.com/2014/01/group-bim-tools-and-parametric-modelling.html) was interesting in the depth she went into in describing Tekla. I had never even heard of the program before, but it sounds like it would be very useful in certain applications. I would be interested in working with the program to see how it works and what it can do.

 Source:

Eastman, C., Teicholz, P., Sacks, R. and Liston, K. (2008) BIM Tools and Parametric Modeling, in BIM Handbook: A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers, and Contractors, John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470261309.ch2