==23649== Invalid read of size 4
==23649==    at 0x36219276: std::_Rb_tree<std::string, std::pair<std::string const, boost::any>, std::_Select1st<std::pair<std::string const, boost::any> >, std::less<std::string>, std::allocator<std::pair<std::string const, boost::any> > >::_M_leftmost() const (stl_tree.h:651)
==23649==    by 0x386EF33E: std::_Rb_tree<std::string, std::pair<std::string const, boost::any>, std::_Select1st<std::pair<std::string const, boost::any> >, std::less<std::string>, std::allocator<std::pair<std::string const, boost::any> > >::begin() const (stl_tree.h:772)
==23649==    by 0x386E968C: std::map<std::string, boost::any, std::less<std::string>, std::allocator<std::pair<std::string const, boost::any> > >::begin() const (stl_map.h:236)
==23649==    by 0x387A3F92: crease::get_sharpness(k3d::split_edge const&) (sds_crease_algorithm.cpp:838)
==23649==  Address 0x28 is not stack'd, malloc'd or (recently) free'd

//code for get_sharpness:

double get_sharpness(const k3d::split_edge& Edge)
{
 for(k3d::parameters_t::const_iterator tag = Edge.tags.begin(); tag != Edge.tags.end(); ++tag)
 {
  // the next line causes the segfault
  if(tag->first == "crease" && (tag->second.type() == typeid(k3d::ri::real)))
  {
   return boost::any_cast<double>(tag->second);
  }
 }
 return 0.0;
}