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Perhaps you've stumbled upon a new feature in MicroStation V8 2004 Edition and wondered what Annotation Scale is all about. This little article will explain how text sizes are controlled and even has a sample file for you to learn from.
To get a better understanding of how the annotation scale can affect the text in your design file, download and open 181_Annotation.dgn. This is a simple little map drawn at 1:1 and it's units are set up in metric. The text you see on the map is defined by using Text Styles and the sizes are being controlled by MicroStation's Annotation Scale. All of the elements that you see on the screen reside in the active model...there are no other models being referenced.
We'll start by simply taking a tour of this file:
From the Models dialog, open Map at 100K
Note the size of the text.
Now go ahead and explore the remaining models and in each case notice the size of the text.
So, how is this working....it's actually very easy!
First of all, MicroStation is using an external resource file called scales.def which is found in the ...\workspace\system\data\ folder. If you open this file with any text editor, you'll notice two columns of information separated by a semi-colon. The left one is the name that will be displayed in the Model Properties dialog, while the right one is the actual scale factor that is used to derive the text sizes.
Let's take a closer look at how scales.def is being used by our sample design file.
Navigate back to Map at 100K and go the the Model Properties dialog.
Notice Annotation Scale picker field displays the value 1:100000.
Similarily, the other models in this file have thier annotation scale set accordingly.
By poking in the Annotation Scale field you will see a picklist of all of the available scales...and guess where these scales are coming from? If you guessed the left column in scales.def you're absolutly right!
To change the scale of the text in any one of the models, you can simply select an alternate scale from the above picklist. In doing so, you will be asked if you'd like to propegate the new annotation scale to the annotation. Answering Yes will automatically resize the text based on the new scale. On the next page we'll take a look at what's going on behind the scenes.
In order for MicroStation to be able to do the necessary math, you'll want to ensure that the Annotation Scale lock is on.
Now that that's out of the way, do an Element Information on one of the pieces of text above a pipeline. In the Details tab of the resulting dialog you'll find two bits of information.
Just for fun, do an Element Information on some pipeline text in each of the three models and note the different sizes and annotation scales:
Map at 50K
Text Size = 42.5, Annotation Scale = 50000
Map at 100K:
Text Size = 85, Annotation Scale = 100000
Map at 250K:
Text Size = 212.5, Annotation Scale = 250000
So, the question is now: How does MicroStation figure out the correct text size? Well, go to the Text Styles dialog and navigate to the text style called Pipe.
From the General tab, notice the following:
With a little mathematics, we can calculate the final text size in the model as being the text size X scale factor.
Map at 50K
0.000850 x 50000 = 42.5
Map at 100K
0.000850 x 100000 = 85
Map at 250K
0.000850 x 250000 = 212.5
At this point, you should be able to create a new model and set the desired Annotation Scale. Although you can set the scale after the fact, it's desirable to do so when the model is created.
Once you've created a new model, go ahead and populate it with some text. Then again, you may as well create some of your own text styles and control thier sizes with the Annotation Scale. Have Fun!
AskInga Article # 181