How To: Use Microstation data linked to external tables such as MGE or Geographics in ArcGIS
Instructions provided describe how to use Microstation data linked to external tables such as MGE or Geographics in ArcGIS. Intergraph MGE data sets and the similarly formatted Bentley System's Geographics data sets both consist of Microstation design files linked to external database tables. ArcGIS software can read Microstation files and database tables. To recreate the same database table links created in MGE, Geographic or other Microstation applications within ArcGIS, re-establish the table links between the design file elements and the external tables.
Users must have some knowledge of the contents of the Microstation design file to determine which objects in the drawing belong to a given data collection. Often a collection of design file elements can be analogous to an ArcGIS feature class. By isolating the design elements that constitute a single feature class, data groupings can be created that are the same as they were in MGE or Geographics, including the externally linked attributes.
The key to re-establishing the table links to the features is the MsLink- and MsCtlg- values that are stored on Microstation elements within the design file. In the Microstation design file a single element may be linked to multiple external database tables. Each table can be joined by repeating the process below.
In order to know which external database table a Microstation elements is linked to, the locations of the external tables must be identified and a database connection must be established to that database. Included in the database is a special 'catalog' table. The 'catalog' table contains a list of the names of the feature attribute tables linked to the Microstation elements.
The MsLink- and MSCtag- values are written as pairs on a database-linked Microstation element. The MSCtlg- value is an integer that specifies the record number within the special 'catalog' table. To know which table any given design element may be linked to, the catalog table must be referenced to locate the table that the MSCtlg- value is pointing to.
When the desired table is known a simple table JOIN or RELATE can be created in ArcGIS to re-establish the database links.
- Add the desired ArcGIS CAD feature class to ArcMap.
- Add the 'catalog' table to ArcMap. The location and connection information must be known. Browse the 'catalog' table and make a note of the table names and their corresponding MsCtlg- values for each table required.
- Open the CAD feature attribute table and browse the feature attributes. Make note of the MsCtlg- value on the CAD features to be joined or related to the external tables.
- Right-click on the newly added layer in the table of contents to isolate the desired CAD features, and open the property sheet of the CAD feature class. Turn off any levels from the drawing layers tab that contain elements that are not to be considered part of the feature class linking to the external database file. Or, use an expression, defined from the definition query tab, to define the contents of the feature class.
Using an expression based on a specific MsCtlg- value ensures that only objects joined to a specific table are included in the feature class.
- Perform the table join or relate by right-clicking on the CAD feature layer and selecting the join or relate option. Complete the join or relate property sheet using the CAD feature class and the corresponding Mslink- value with the appropriate table referenced by the MsCtlg-value. The key field, in both cases, should be the MsLink- and MSLINK column. Repeat for as many tables that have Mslink-/MsCtlg- pairs.