Exporting a feature class to an AutoCAD DWG file converts polygons to circles

Description

In some instances, exporting a feature class to an AutoCAD DWG file using the Export to CAD tool displays polygons as circles or ellipses if the input feature class used in the tool was converted from a DWG file using the CAD to Geodatabase tool.

Cause

The following are possible causes for this issue.

• When AutoCAD blocks (inserts) are converted into a geodatabase (GDB) using the CAD to Geodatabase tool, the components of the blocks are separated into point, line, and polygon feature classes. However, the Entity field identifies these features as inserts. Hence, when converting back to a DWG file, the Export to CAD tool uses the information from the Entity field to create more blocks (inserts) than what is expected.
• When zero-length lines with radii are imported from CAD data to a GDB, circles or ellipses are created when using the Export to CAD tool.

  Note:
  A block is the term used in Autodesk programs - AutoCAD and others - to refer to a point feature that can contain points, lines, polygons, text, and other feature types, and displays with a specific symbol in the Autodesk program. These features appear as points in ArcGIS, and the Entity field in Esri software is populated with the term "insert", so a point identified as an "insert" in Esri software is the same thing as a block in AutoCAD.
  

Solution or Workaround

As a workaround, follow the instructions provided below.

• Upgrade to the latest version of ArcGIS Desktop

  This issue has been fixed in the ArcGIS for Desktop 10.3.1. If using a previous version, it is recommended to upgrade to the latest version of ArcGIS Desktop. For more information, refer to the following Help document, ArcMap: What's new in ArcMap.

• Ensure there is only one point insert for each block insert

1. Convert the DWG file into a GDB file using the CAD to Geodatabase tool.
2. Open the attribute tables of the output data.
3. In the attribute table of the point feature class, ensure there is only one point designated as the insert for each block insert. 
4. In the attribute tables of the polyline and polygon feature classes, ensure there are no insert entities.
5. If there are insert entities in the polyline and polygon feature classes, start an edit session, and change the insert entities to LWPolyline.
6. Add a CADType text field to the point feature class.

   Note: 
   The names LWPolyline and CADType are reserved for CAD field schema. For more information, refer to the following Help document, ArcMap: Reserved CAD fields for AutoCAD DWG/DXF formats.

7. Using the Entity field, copy each corresponding entity type to the respective CADType field.
8. When executing the Export to CAD tool, specify a seed file that contains the block definitions. For more information, refer to the following technical article, How To: Create AutoCAD block inserts with attributes from ArcGIS point features.

• Densify the problematic points (true curves) in the input dataset

1. Locate the circles in the output of the Export to CAD tool.
2. Start an edit session with the input data.
3. Select the problematic points (true curves) that are creating the circles or the ellipses.
4. Densify the true curves using the Densify tool. For more information, refer to the following Help document, ArcMap: Densify.