It seems that this conversion represents a translation of 3d graphics saved in Cinema 4D format (.c4d) to a Universal 3D format graphics (.u3d). Apparently, this conversion is possible and can be done with some of the dedicated 3D conversion tools, such as PolyTrans.
Convert CINEMA 4D file format to Universal 3D format graphics.
We found 2 software records in the database related to .c4d to .u3d file format conversion.
Microsoft Windows software - convert c4d to u3d on Windows
A CINEMA-4D converter
Convert from c4d file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned c4d to u3d. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 3D CAD translation softwate