Will the following two lines work if pts are of a vector of Points instead of an array of points ? Point pts2[numcorners2]; //chaged to std::vector pts2; gtl::set_points(poly2, pts2, pts2+numcorners2); And lastly, does anything about the following loop stand out to you as bad accessing of Polygon points ? for(std::size_t i = 0; i < num_polys; ++i) { pts.insert(pts.end(), polys[i].begin(), polys[i].end()); num_points_in_poly=pts.size(); numpointsperpoly.push_back(num_points_in_poly); for(int index =0; i < num_points_in_poly; index++) { std::cout<<" Here are the stubborn points x= "<<gtl::x(pts[index])<<", y= "<<gtl::y(pts[index])<<std::endl; tempcorner.assign(gtl::x(pts[index]),gtl::y(pts[index]),0); unioncorners.push_back(tempcorner); } } Thanks again, you're a lifesaver. -- View this message in context: http://boost.2283326.n4.nabble.com/Polygon-accessing-Points-Data-tp3446015p3... Sent from the Boost - Users mailing list archive at Nabble.com.