a bug in virtual_scanner/polygonmesh.cpp

[zhoujianling]

In polygonmesh.cpp line 154, there is an obvious bug:

   if (argc > 3) // should be 'argc > 5'
    {
        start_id = atoi(argv[3]);
        end_id = atoi(argv[4]);
        model_id = atoi(argv[5]);
    }