Hi, how can I export stl files in higher resolution? The dgn files that I export to stl files is not perfect round but instead small lines put together in a circle?

I am trying to export DWG (3D contours) to 3D PDF. Whilst exporting in 3d PDF file, some contours are being displayed as regions. Is there any way I can export them as polylines instead? I have worked around with Entity Mapping settings already but no…