Ch. 2 BIM Tools and Parametric Modeling

I too like W. Chunyi did not have any exposure to BIM prior to reading this chapter. Now that I have read Chapter 2 BIM tools and Parametric Modeling of the BIM Handbook, I have a better understanding of how BIM works and can see that it is an extremely powerful tool.

BIM is an innovative approach to building design, construction, and management that is characterized by the continuous availability of highly accurate, consistent and reliable building information. BIM allows the project team to visualize, simulate, and analyze a project before construction even begins using a three-dimensional model representing all of the physical and functional characteristics of a facility.

BIM was developed in part to address the issues of data loss as a building project moves through the various stages of development – from initial design to construction to operation. Refer to G. Carpenter’s post because I believe she explains this best in her opening paragraph.

Parametric Modeling is an approach to building construction that is characterized by designing with objects having real-world behaviors and attributes. Original (2D and 3D) CAD engines used specific, coordinate-based geometry to create graphic objects. Editing was burdensome and extremely error prone. Documentation was created by extracting coordinates from the model and generating standalone 2D drawings. As graphic engines matured, graphical entities were combined to represent a design element (a wall, a window, etc.). Surface and solid modelers added more intelligence to the elements and enabled the creation of complex forms. But the result was still an explicit (coordinate-based) geometric model, which was inherently difficult to edit and had a tenuous relationship to extracted drawings that easily fell out of sync with the model.

Then came parametric modeling engines that used parameters (numbers or characteristics) to determine the behavior of a graphical entity and define relationships between model components. For example, "the diameter of this hole is 1 inch" or "the center of this hole is midway between these edges.” This meant that the design criteria or intent could be captured during the modeling process. Editing the model became much easier and preserved the original design intent.

With state-of-the-art parametric building modeling, BIM software can coordinate a change made anywhere and everywhere it matters: in 3D views and drawing sheets, schedules and elevations, sections and plans.

BIM is not perfect there were many shortcomings in early BIM as discussed by my fellow group members and in Chapter 2 of the BIM Handbook. Also, C. Meraz made a good point in that the current design methods used “where each system is designed and contracted separately lacks the required coloration necessary to avoid the current ‘clashes’.”




Sources:
Chapter 2 of BIM Handbook (2008)
http://en.wikipedia.org/wiki/Building_information_modeling