Instructions provided describe how to convert Microstation-based Modular GIS Environment (MGE) or Geographics data to ArcGIS feature classes. Both Intergraph's MGE and Bentley's Geographics CAD-based GIS applications use a data structure, where Microstation drawing elements are linked to external database files using a combination of the MSLink and MSCatalog values.
A sample geoprocessing model is included in the CAD Translation Sample Toolbox to help automate the steps for converting MGE or Geographics data into ArcGIS feature classes.
Below is an outline of the logic used in the included MGE_CADtoFC sample model tool.
- The input to the sample model is a Microstation drawing containing elements with [MSlink] values that correspond to those in an external database table.
- The sample model tool uses the SELECT DATA tool with the Child Data Element parameter exposed as a variable to allow the selection of which CAD feature class (POINT, POLYLINE, POLYGON, ANNOATION, or MULTIPATCH) to use as the feature source.
Alternately, in a simplified model, a CAD feature class can be used directly instead of using the SELECT DATA tool to select the source feature class from the input CAD file.
- The model uses the MAKE FEATURE LAYER tool, which provides a means to perform a filtering query using the exposed expression parameter.
Building a query based on the [MSCatalog] property included on the CAD elements is a good way to select all Microstation elements that are linked to the same MGE or Geographics feature table. The [MSCatalog] value is a reference to which table a MSLink value is related to. The [MSCatalog] refers to which table and the [MSlink] value indicates the record number in that table. Together the two values point to a unique record.
The MAKE FEATURE LAYER tool is required to create a needed 'feature layer' from the CAD feature class. In Geoprocessing, tables can only be joined to 'feature layers' and not directly to feature classes.
- The resulting feature layer is joined to the external table using the ADD JOIN tool. The feature layer is joined to the external table based on the common [MSLink] value in each table.
- The combined result is the selected Microstation elements joined to the external table records. The feature layer can be output to a new feature class using the COPY FEATURES tool.
Alternately, use the FEATURECLASS TO FEATURECLASS, SELECT, or APPEND geoprocessing tools to perform the final task of writing out the output feature class.