Saturday, April 9, 2011

Hello! Singular Repetition

This is the first post on littleBIM which aims to be broad in scope, short on pomp, and long on practicality.

Some tenets of Architectural documentation are put in whole new light as Building Information Modeling (BIM) becomes commonplace. One of those is the dictum "say it once, say it correctly, and say it in the right place in the documents."

In one sense, a given piece of information in a BI Model can be accessed from any number of views therein. While that datum is certainly lodged only once in a specific, unique location in the model data structure, it is likely to be expressed in a multitude ways, and expressed in output in a number of places. So, while we only say it once in one place, the model says it, and a model user hears it in many times and places, and there is no getting around that ... until we plot it on a sheet of paper. Then we can control it all again. Shall we take extraordinary measures to prevent access, or to avoid the expression of that information in more than one place to a model user? I don't imagine so.

Today, most of us still build from 2D paper documents even when we have designed in a virtual multi-dimensional environment. So it is the rectitude and consistency of the plots and printed specifications that is critical. It can be argued that it really doesn't matter how well crafted the model is, as long as the hardcopy is right. And in court, that is true. 

In some future post, I may deal with the downside of workarounds that look just fine in the plots, and the glories of that golden day when it will no longer be necessary to translate our 3D designs into 2D for presentation on paper, and when we can trust our software implicitly.

But the topic of today's post is the duplication of information (or its despised corollary: the internal contradiction of information). Among the most interesting of the kinds of model elements which will never be built are those which report information about modeled elements in alphanumeric characters. The most sophisticated of this class of elements is the Schedule, whether it shows information about door frames, door leaves, windows, footings, beams, or assemblies, but Dimensions are another, and Zone identifier stamps or labels are another. There should be no reason for the same information not to be reported more than once in the printed documents if it improves their usability. After all, it is the same information. Assuming that we have modeled carefully, that the reporting elements work properly, and that we are smart enough to use them properly, there is no chance of contradiction. If the duplication is not gratuitous, but functional, I suggest that it is a good thing, not a bad thing. 

Some examples: 
The length of a wall may be given from CL to CL on a floor plan. Is there a good reason not to close a dimension string between finished faces of those walls in an interior elevation of the room enclosed by those two walls? I imagine not.  
If I have defined two labels - one to count occupants for egress purposes, and another to count occupants for calculation of required parking or plumbing fixtures - is there a good reason that the same room area should not be displayed in both (or many) different labels displayed in several different views and presented in several places on output hardcopy? I imagine not. 

Both these situations seem to violate the opening dictum. Is it becoming a shibboleth?

P.S. - 
A person checking plots cannot know whether the ink on the paper represents model data, a workaround in the model, a 2D vector drawing in the model but not extracted from modeled elements, or an image with no connection to any model data. Drafters: Please do not abuse the opportunities this opens to set booby traps for others who may need to make sense of your model after you have finished with it.