Hi, the following code produces some strange results: typedef cs::spherical_equatorial< boost::geometry::degree > cs_type; typedef model::point< double , 2, cs_type > point_type; typedef model::linestring< point_type > linestring_type; point_type p( 1.0 , 1.0 ); linestring_type l; l.push_back( point_type( 0.0 , 2.0 ) ); l.push_back( point_type( 2.0 , 2.0 ) ); l.push_back( point_type( 4.0 , 2.0 ) ); cout << "Distance : " << boost::geometry::distance( p , l ) << endl; for( size_t i=1 ; i<l.size() ; ++i ) { linestring_type l_tmp; l_tmp.push_back( l[i-1] ); l_tmp.push_back( l[i] ); cout << "Point distance : " << boost::geometry::distance( p , l_tmp ) << endl; } The output is Distance : 0.0174373 Point distance : 0.0174586 Point distance : 0.0174373 This looks like a bug. The distance to the second segment can not be smaller than that to the first one. If I change the coordinate system to cartesian coordinates everything works as expected. Do I miss some major points?