I will explain how annotation scale is useful for setting your reference scale in the Create Dynamic Views dialog. Once you set the annotation scale for Sheet, you don't need to bother about the Reference scale (Master:Reference (M:R)) factor for reference attachments. It will automatically get calculated & reference gets attached at correct size. To keep things easy, let us ignore Drawing model for the time being.
Before seeing how Reference scale (M:R) factor is calculated from annotation scale, first we need to understand Detail Scale for a reference attachment. Detail Scale simply represents the Reference scale in terms of sheet annotation scales. For example, consider a Sheet model with annotation scale 1/8" = 1'; it will typically contain drawings that have a detail scale of 1/8"= 1' (M:R of 1:1). Now, if you want to place a drawing twice as large, you can avoid calculating the appropriate Reference scale factor, by simply setting detail scale to ¼" = 1'(which will automatically set M:R to 2:1). MicroStation then calculates the Reference scale by the following formula.
Reference scale = Sheet Annotation Scale / Detail Scale
By default, Detail Scale for a reference is inherited from the annotation scale of the model being attached (design model). In the special case where the design model does not have a valid annotation scale (legacy files), annotation scale of the sheet model is used. Reference scale is then calculated by dividing the sheet annotation scale by the detail scale.
The Create Dynamic Views dialog helps to create a new sheet model and place a design model's saved view as a reference attachment. Based on the above rule, it uses the design model's annotation scale as the new reference attachment's detail scale. When you specify the new sheet's annotation scale, the new reference attachment's Reference scale is calculated as the ratio of sheet annotation scale and detail scale.
There are two basic workflows to create sheets.
Workflow I: Attach design model at full scale (as designed) and scale up the sheet boundary to fit the design.
Workflow II: Keep sheet boundary at full scale (paper size) and scale down the design model to fit the sheet.
Workflow III (optional): In some cases, you may have to scale both design and sheet to get the desired result. I am mentioning this hybrid workflow only to illustrate the point.
Below are some examples which will help you to understand how Reference scale (M:R) is calculated for different workflows.
Design > Sheet Attachment
Design > Sheet Attachment (Hybrid)
Now, if our workflow includes the intermediate Drawing model (Design > Drawing > Sheet), there are a few key points to note:
1) We always attach design model into drawing model with at scale of 1:1
2) Drawing model will be attached to the sheet model at the desired scale
Design > Drawing > Sheet Attachment
While using Create Dynamic View dialog, we always attach the reference with "Use Active Annotation Scale" ON. This allows annotations in the reference to use annotation scale of the active model. I will focus on scaling annotations in reference with the active model's annotation scale in my upcoming blog on annotation scale. So be there.
Everybody, see the discussion here, how MicroStation 8.11.7.x gives me headache with the new philosophy: