Esri Mapping Specification for CAD (MSC) Reader/Writer

The Esri Mapping Specification for CAD (MSC) Reader/Writer allows FME to read and write Esri MSC data found in Autodesk DWG files.

Reader Overview

This reader provides almost all the functionality available within the Autodesk AutoCAD DWG/DXF Reader Parameters with the following exceptions:

  • Schemas are generated based on the MSC feature class information found in the DWG file, rather than on layers, geometries, or attribute schemas.
  • The schema will be generated using MSC feature classes as FME feature types. This mode groups entity information and related attribution by feature class via the creation of a data feature for each an entity selected by each feature class
  • If a certain entity is selected by n different feature Classes then n different features are created, one for each feature class. Each feature will store a copy of the entity information referenced and have attribution from only the feature class that it represents. Data features created for two different feature classes which select the same entity will have identical values for the msd_entity_key attribute.
  • If an entity does not have any feature class which selects it, then it will not be read.

The traditional autocad_entity attribute will be added to features to provide additional information.

Writer Overview

This writer provides almost all the functionality available within the Autodesk AutoCAD DWG/DXF Writer Parameters, with the following exception:

  • The Append Data to Template File parameter is not supported for Esri MSC writing.

In addition to the DWG/DXF parameters, the Esri MSC writer introduces some new parameters not used by the AutoCAD DWG/DXF Writer.

When creating AutoCAD files, the Esri MSC writer first defines the linetypes, layers, and MSD feature classes defined within the FME workspace. The writer then reads in a template file, if specified, and copies the linetypes, layer definitions, shape file header information, and block information from the template file to the output dataset. Any feature classes in the template file will not be copied.

The Esri MSC Writer takes each feature that is given to it and outputs it to the destination dataset according to the appropriate msd_type type. The traditional autocad_entity attribute will be considered, if present, when writing entities, though the msd_type will be preferred if type conflicts occur.

All entity types will be checked for MSC information according to the attributes defined on the feature class. The attribute information on features is written as MSC attributes for each feature written to the dataset.

Notes

  • Feature type fanout will affect both the feature classes and layers. The name of layers may not be overridden, even by the autocad_layer attribute, and feature class names may not be overridden, even by the msd_feature_class_name attribute.
  • Feature class queries created by the Esri MSC Writer are fixed to select the layer with the same name as the feature class.
  • Default values for the attribute schema of feature classes created by the Esri MSC Writer are fixed to 0 in the case of numeric attributes, and empty strings in the case of string attributes.