Original Article Date: Nov 6, 2001
So, you've heard that MicroStation V8 now supports the concept of multiple models contained within a single DGN file. But did you know that models are cell definitions and vice versa? That's right, MicroStation V8 makes no distinction between cells and models whatsoever!
I'm tickled pink to introduce Mr. Frank Conforti as the author of this article. As many of you know, Frank is a dynamic speaker, excellent writer and enthusiastic evangelist for MicroStation and many of Bentley's other products. Thank you Frank for an interesting article and welcome to the AskInga community!So, you've heard that MicroStation V8 now supports the concept of multiple models contained within a single DGN file. But did you know that models are cell definitions and vice versa? That's right, MicroStation V8 makes no distinction between cells and models whatsoever!For example, open the delivered ...\Workspace\System\cell\sample2.cel as the active file. Then select File > Models and note the resulting dialog:
Before we go on, let's try and understand what a model is all about. A DGN file is now simply a "container" or "folder" that can contain both 2D and 3D objects known as models. (You may also notice that we now refer to "design files" as "DGN files"....since they contain much more information now than just your design.) This is why you can reference 3D DGN files to 2D DGN files, place 3D cells in 2D DGN file and the like. Now, each model is stored as an object within the DGN file and a DGN file can contain more than one model. Not unlike V7 design files, each model has it's own set of eight views and when you are viewing one of the views of a model it is known as the active model. Sound confusing? Not to worry, you'll have this figured out in no time at all. Just remember, that when you place elements in a DGN file, you are actually creating or working with a model. By the way, to work on one of the models of our open sample2.cel file, just double-click one of the model names in the dialog shown above. Anyway, I got to thinking about this...if a cell is a model then a cell library must be the same as a DGN file, right? That means I could theoretically attach a file to itself as a cell library. Go ahead and give it a try and you'll see that it works!Now, why would I want to do this, you ask? Well, if you want to quickly convert a bunch of section details to, say, individual models(cells) for easier maintenance (remember, you can now edit cell definitions just as easily as DGN files!), all you have to do is identify the elements you want, place a cell origin and issue the Create Cell command. Viola! Your collection of elements just became another model in your current DGN file! Select the next bunch of elements that make up a detail, repeat the process and you have yet another model and so forth.For practice, you can try the following little exercise in the sample2.cel file that you have open. Be sure that your active model is default and draw a new symbol. Gather up the elements with either a Fence or the Element Selection tool and then define your cell origin. Finish creating the cell and notice that you now have a new model with the same name as the cell you've just created!
Now that you've converted all those discrete section details into models in your DGN file you can use them in other files either as references (old term: reference files, they ain't necessarily files anymore) or as cells...the choice is yours!Note that the major difference between a cell placement and a reference attachment of a model is that references are still linked to the originating file whereas the cell encapsulates the contents of the model in the receiving file (the one you are placing the cell in.) That is the only difference between the two. You can always update the cell definition by performing an Update Cell operation.This idea of cells being models and models being cells is only just now beginning to sink in. I can see some real possibilities as we explore this exciting new V8 ability especially as it relates to 'presentation' versus 'design'. In the meantime, here's one for you to chew on...If a model has a reference attachment in it and you place it as a cell, what happens to that reference attachment (the answer is really cool!) See ya next time!
AskInga Article #86