B2 - A brief history of Parametric Modeling

3D modeling has been in development since the 1960s. The need for 3D graphical representation was clear, and many potential fields were looking to benefit from it, including engineers, architects, filmmakers, and game designers. The first major step occurred in 1973 when the ability to create and edit solid 3D volumes was developed independently by various institutions. In the early stages of 3D modeling, two major forms competed for dominance: the boundary representation approach (B-rep) and Constructive Solid Geometry (CSG). B-rep represented shapes as a closed set of bounded surfaces which was set by the user, and built-in computational functions in place to allow these shapes to have dynamic dimensions. Commonly used shapes were built into the software (such as cylinders, cones, cubes, pyramids, etc.) but abstract shapes could be user-defined and then extruded or revolved. In CSG, a shape was represented as a set of functions combined through both algebraic and boolean expressions. The primary difference between CSG and B-rep is that CSG stored an algebraic expression to define a shape while B-rep stored the results of the user provided definition as a set of operations. While this may not seem like a significant difference on paper, because the methods had major differences in their back-end systems, they also had major differences in their capabilities. For example, in CSG elements could be edited and regenerated on command, while B-rep was better for computing mass properties of solids, rendering, and checking conflicts between objects.

Interestingly enough, it was eventually realized that these two methods should be combined allowing for editing within the CSG tree. By utilizing the editing capabilities of CSG and combining them with the visual benefits of the B-rep display interface, more complex designs could be made from compositions of basic shapes. Today, practically all parametric modeling tools use this combination for both editing and visualization. Without this innovation, modern parametric modeling would be impossible.

While seemingly unimportant, I think it is interesting to delve into the history of such a powerful design tool to help further our current understanding of the system and platform. Moreover, after knowing this information, I will surely keep it in mind and perhaps have a deeper understanding and appreciation of Revit as I begin utilizing and becoming more comfortable with the software over this term and in my upcoming co-op.

Comments:

Alec: Interesting post. I found your point about construction managers being involved in a BIM model and the design process before the build phase true to an extent, however, there is something to be said about why this isn't always the case. In AE 390, we learned about the "Integrated Design Process" which is a method building design wherein all major stakeholders and designers in a building (i.e. architects, MEP engineers, structural engineers, construction managers, contractors, owner) take part in the design process from day one. This is contrary to the traditional method of an architect being commissioned to design a building, drawing plans, handing them off to the engineers, etc. with little to no communication between these stakeholders. In general, it seems that the integrated design process yields more effective and efficient buildings as all systems are working in harmony, however, from people I've talked to in the industry, it seems that this method isn't always used because it slows down the design process significantly. Here's a video if you're interested in the integrated design process: https://www.youtube.com/watch?v=hIX-J83lmaI

Gabe: I enjoyed your reflection on the chapter--it was interesting to see another take on the same reading that I did. While I focused more on the history of BIM you seemed to write more about the functionality of BIM (ie how it works and how it detects errors). It also seems clear to me that learning about how BIM works enhanced your previous knowledge and experience with Revit, giving you newfound knowledge and a new perspective on a program you are already familiar with. As someone who does not have an extensive Revit background, I will make sure to keep your comments regarding the parametric capabilities of Revit in mind when learning and gaining experience.

Jenny: I liked your post. Your main point--that BIM can be used by managers to prevent collisions and/or construction issues before construction and thus save money--is one that is extremely important but could often be overlooked by engineers. Our peer, Alec Silverstone, brought up a similar point saying that using BIM for clash detection can not only save money, time, and effort, but also can keep managers and construction teams more involved and "in the know" on the design process, something that can help create a more efficient building and save money in the longrun. 

Sources:
[1] Eastman, Charles M. BIM Handbook : A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers and Contractors. Vol. 2nd ed, Wiley, 2011. EBSCOhost, ezproxy2.library.drexel.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=nlebk&AN=364239&site=ehost-live.