Have you tried the ArcStroker transformer? This is probably what I would try first:

Converts arc features into lines replacing the feature geometry with a series of edges interpolated along the arc boundary. Ellipse features are converted into polygons by interpolating edges along the elliptical boundary.

@jnfung - We want to keep the arcs though. We need to keep the radius information on them. I can get them to lines just fine, but that won't work for us, we need to keep the arc information.

Hi @candimk,

FME should be reading the DGN complex shapes with Path boundaries, which can contain a mixture of lines and arcs. 2D paths will be written to DWG as LWPolylines, that can include arcs, but 3D paths will be stroked into 3DPolylines.

If your complex shapes are planar, you can use a ElevationExtractor to save the elevation to the attribute 'autocad_elevation', then a 2DForcer to convert them to 2D. These will be written to DWG as LWPolylines with elevation.

Hi @daveatsafe - I was hoping it would be that easy. When I just do a straight conversion in FME or out of MicroStation itself, the resulting features turn into polylines with the Arcs dropped to lines (I did verify that the drop complex chains/shapes was turned off). These are 2D microstation drawings, so I shouldn't have to worry about elevations.

The closest I can get is to drop the complex chains/shapes, then use snapper and LineCombiner to build those polylines back based on level, however that usually only connects one or two lines, not the whole thing. But it does keep the arcs. I was hoping to have the best of both worlds.