There are a couple of utilities converting `polymake` file format from and to other formats used by various useful software packages. These collections is currently very small, but it grows by demand.

poly2leda_graph <file> <graph_section> { -directed, -undirected }
Convert a polymake graph into a leda graph, write the latter to standard output.
obj2surf <out_file> <in_file>
Convert a Wavefront obj description of a polyhedral surface into polymake Surface format.