Yes, it's possible to achieve a successful conversion but you will need to export your C3D surface file as DEM and then use DLGV32 application. There are other workarounds, but the problem is you will not get any top quality for the converted files. It has been reported that the above mentioned application can do the job without too much of a hassle and besides that, it exports the files with top quality. To download DLGV32, access the official website. Use version 5.10 from the download page.