Learn the history of the DGN file format and how it compares to the DWG file format to help you better understand the differences.
- [Instructor] This chapter the basic file types used in MicroStation, how to open and save files, and how to create a new design file. We'll also discuss some of the basic settings defined in a design file that can affect your graphics. Open the file for chapter two, basic DGN concepts .DGN. First, let's explore a little history on the DGN file format. The DGN file has been the foundation of MicroStation since it's inception in the 1970's. Even though the software was not called MicroStation yet, the file format was the reliable DGN that we have all learned to love.
This format was very fast and efficient and more than satisfied the needs of that time frame. With the explosion of Windows and CAD capabilities over the past few years, many of us anxiously awaited an overhaul of this DGN format with the release of the V8 DGN file format. Here is a comparison of both DGN file formats. On the left, you see the properties from the previous version 7 DGN file format. On the right, you'll see the properties from the V8 DGN file format.
The implementation of many of these unlimited properties enhanced several of the capabilities that we have now have available in MicroStation. And many of these are similar to what you have in the AutoCAD environment. The reason I bring up such old DGN history is to help you understand why you see some of the data in the legacy DGN files in what appears to be very old naming and standard conventions. Now you see why the old DGN file used level numbers rather than level names.
Also, this is why DGN files contain multiple colors, line weights, and line types all on the same level. When we had the limit of 63 levels for many years, MicroStation users had to get creative in how they could distinguish specific graphics for multiple purposes. With the introduction of the V8 DGN format, these limits were removed and users now use level names with the unlimited levels, which allows for a more logical way of separating design data.
Not all users made this transition, so you can still find DGN files with multiple design content on a single level using properties, rather than level, to distinguish between design data. The MicroStation design file uses a .DGN format and extension. MicroStation files can actually have any extension, however it is recommended that you use the .DGN for consistency and standardization. MicroStation also uses cell library files to store standard cells, similar to blocks in AutoCAD.
A cell library file uses a .CLE extension by default, but the format of this file is identical to that of a .DGN file. The .CLE extension is used to differentiate it from the other file type. Another important file type for you to learn is the DGN library file. A DGN library file uses the .DGBLIB file extension, and as with the others, it's format is identical to the DGN file format.
Again, the .DGNLIB extension is used to differentiate it from other file types. The DGNLIB extension can also be used with work space configurations. A design library file contains standard styles, such as tech styles, dimension styes, line styles, levels and many other standardized properties and definitions. There are also two types of a .DGN file. Specifically 2D and 3D. Both of these file types define a global origin which specifies a unique 00 location in the design plane or design cube.
This global origin is located in the center of a 2D flat plane or a 3D cube by default. The 2D DGM file provides a flat 2D drafting environment, similar to a sheet of paper. This environment has limited design plane, and or edge of paper, where data can be input using X and Y coordinates only. The 3D DGM file provides a 3D cube drafting environment, similar to that found in the AutoCad environment. This 3D environment consists of a limited design cube where data can be input using X, Y, and Z coordinates.
Now let's take a look at how to open and save files using MicroStation. Using the pull down menu, select file, open, to access the file open dialogue. When opening MicroStation design files, the default filter type is defined as the most common file type. .DGN for MicroStation, and .DWG for AutoCAD. Modify the files of type drop down list to easily open other CAD file types. As you can see here, MicroStation opens almost all CAD file types out of the box.
When it comes to saving files, MicroStation is different than all other Windows applications There is no save for a MicroStation file. MicroStation uses a continuously saved file process, eliminating the need for users to perform manual saves. This occurs as MicroStation stores all work in the actual file on the hard drive, rather than in the computer's memory, unlike other software applications where manual saves are required. This eliminates the risk of losing data as the result of a software failure.
This automatic save can be modified to work like other applications using your user preferences. I will select the pull down menu workspace, and preferences. Using the preferences dialogue, I will select the operation category. Here you can find the setting to automatically save design changes turned on by default. You can turn this off to make MicroStation work like other Windows applications, such as AutoCad. However, it's not recommended as there is no automatic back up being made in the background.
I recommend that you leave the automatic save turned on, and just get used to it. If you do disable the automatic save, you can configure an automatic file backup using the configuration variable MS_BACKUP. I have defined this variable to automatically back up all design files to the following folder. To run a manual backup, I need to use the key in command backup. Key in the command backup and hit enter. If you look at the status bar, you can see that the active design file has been backed up to this location.
You can also define an automatic backup time, using the background MicroStation application backup. And the configuration variable BACKUP_TIME. I have this functionality committed out for this course, but if you look in the user configuration file delivered with this course, you can see how to do define this variable in minutes. In MicroStation, add on applications are called user commands, MDL Apps, Macros, or VBA applications. Similar to list, visual list, and VBA in AutoCAD.
The next exercise will discuss how to you seed files to define standard settings for future design files.
- Using menus, settings, and toolboxes
- Modifying MicroStation preferences
- Working with DGN files
- Leveraging multiple views
- Using AccuDraw and AccuSnap
- Drawing lines, shapes, and forms
- Rotating, stretching, and scaling elements
- Trimming and modifying elements
- Selecting handles and element attributes