There's options to specify how detailed the resulting polygon mesh will be.

In all other cases the NURBs data in CAD files has to be converted to polygons during import through a process called tessellation. Finally the JT format can include three different models with varying levels of detail, and those can be imported as an LOD object. CATIA files with the CGR extension only include a polygon mesh. Some JT and STEP files include a polygon version of the model, and you can import that by choosing the Source Mesh option. Many CAD files don't include built-in materials, and in those cases you can choose to generate materials based on the display colors. If the CAD file includes materials, you can choose to use those - or you can use the built-in materials with random coloring to easily distinguish each material. You can choose to use the built-in display colors or assign random colors to easily distinguish each part. Besides choosing what type of data to import, you have detailed control over how to handle the layers, normals, display color, and materials from the CAD file. All the CAD formats share the same options dialog, though you can set different defaults for each format. Import CAD formats just like any other file using File > Open or File > Merge, or by dragging and dropping. Cinema 4D Release 20 now includes native import of Catia, STEP, IGES, Solidworks and JT files so you can easily make use of CAD data provided by clients.

Cinema 4d r20