Travis Van Clieaf discusses CAD graphics standards in the context of BIM today.
CAD graphics standards with the term ‘budding’ in front of BIM users might cause you to wonder what the reason is for that. The reason I wanted to write about graphic standards is because I feel it’s very important; as we embrace BIM and move forward with new technologies, that we don’t forget where this BIM technology came from.
At its root, there is a pencil. A former mentor of mine would come into the office in the morning and say ‘Alright, let’s get that graphite burning!’ His statement harkens back to a time where architects, engineers, and draftspersons would essential burn through pencils and paper to create the drawings that would eventually become buildings. What a process, so laborious right?
It was the way, so nobody was really thinking of it any differently than ‘this is a section view’, or ‘this is a plan detail’. These elevations are drawn this way and if I’m showing steel cut in section, I use this universally understood hatch to show it. It didn’t even require a note because those hatch patterns were known by all who laid lines down on the paper, and all who read them.
Today, we’ve moved forward from this, manual drafting has given way to CAD for some time, and many of us still employ this method to earn our daily bread, however, BIM is becoming a very widely adopted method of creating drawings. I’m not going to get into the benefits of BIM in this one, I’m sure any of you who have read anything else I’ve written; know I am a huge proponent of modeling over drafting. The truth is, inside our BIMs….is a whole lot of CAD. Any sketch based element, like a roof or a floor, is done with drafting, so you could say before there could ever be BIM, there had to be CAD, it’s simply the evolution of a process. BIM encompasses CAD, CAD is still Building Information Modelling, it’s just done in a more fundamental fashion, which leads to my ultimate point in this article.
You can’t have BIM without CAD, and you can’t have CAD without knowing drawing conventions. I find the most befuddling objection to moving to BIM is ‘Revit doesn’t produce drawings the way we like to send them out’ because no CAD platform creates drawings the way you’d like to send them out. Knowledgeable people create those drawings and the software is simply the tool. When we work solely with AutoCAD or any other CAD based platform, and we start fresh, there is still a lot of front end work that needs to be done, to define a template of line types, line weights, layer styles, layer naming conventions, blocks and of course the .CTB file to make it look beautiful when it comes off the ‘plotter’.
So why is it so hard to understand that the same will be required when we transition to BIM? I myself was guilty of this, ten years ago when I first saw the product of Revit. In its early days in the Autodesk family, people focused on the speed of Revit, the productivity enhancements and the ability to catch flaws in a design, but graphics was what I saw initially, or should I say the lack thereof. The linework seemed flat, the hatches all wrong, and I don’t think I saw a decent detail done with BIM for quite some time after that. To this day, I still see people fully functional with BIM, but they still use AutoCAD details…and why not? If they’re drawn right and reference back to the model properly, what’s the harm?
My concern as a trainer is when I see people who have studied architecture or architectural technology and they don’t recognize the drafting conventions that have been around for ages. These are things that you need to know because not only do they make your drawings correct, but they help you identify what may be going on in your model.
A simple example is a concrete floor in Revit; typically a floor isn’t ‘drawn’ in plan, its outline is depicted by the boundary of walls supporting it. However, in Revit, floors are typically a sketch based element. If you cut through that floor in section, you should see a very specific hatch, and then from the plan view, a subtly different hatch. It’s essentially the same, only there are no triangles in it, so you’d know if you saw that pattern in plan, one of two things is happening:
1) My cut plane in the View Range is not set to 4’, but might be set to be cutting through the floor, or
2) for some reason, the surface pattern of my floor was set to be a drafting pattern and not a model pattern using the ‘Sand’ hatch in the material’s settings.
There are probably a couple other things that it could be, but off the top of my head, these would be the first two things I’d identify and I’d know to look at them because of familiarity with drafting conventions of architecture.
Because of the power of computers and design software, we’ve come to rely less and less on our ability to draw with a pen or pencil. We take for granted that everyone uses a pencil or a pen, so it doesn’t require as much education or training as working the software does, but it is indeed the foundation. Joe Business Owner obviously needs to use a writing implement as well, but how an architect or designer uses a pencil is an entirely different thing, there are a lot of things that you need to know to make these drawings look ‘correct’.
As team leaders or mentors, we have to ensure our up and coming designers are able to read and replicate these details and draw them correctly, so that when they are looking into the guts of a BIM, these issues can be quickly taken care of. It’s not just about how correct the drawings are , but how well you can work with the new tools. Of course, developing a good template will eliminate the need for fussing with these things, but I say, ‘knowledge over resources’. If your best designer, draftsperson or producer decides they want to take up painting landscapes instead of designing them, or yes, even retire, then you’ll need knowledgeable staff to pick up where they left off, and even the most well developed template will be of no use if people aren’t able to easily interpret design information or work the tools to develop it.
~ Travis Van Clieaf
*Foundation detail and design elevation courtesy of Clayton James Hartwell