https://svn.boost.org/trac10/ticket/10866 <p> In 1.55 union_ merge two polygons but in 1.56 and 1.57 doesn't. I use long double as a coordinate. </p> <p> Take a look at the following testcase: </p> <p> boost::geometry::union_(<a class="missing wiki">MergedPoly</a>, gpolygon, Result); printf("result count = %d\n", Result.size() ); </p> <p> Merged Polygon: x = 8126 y = 3.18455e+07 x = 8127 y = 3.18455e+07 x = 8129 y = 3.18455e+07 x = 8130 y = 3.18455e+07 x = 8130 y = -146305 x = 8129 y = -146306 x = 8127 y = -146306 x = 8126 y = -146305 x = 8126 y = 3.18455e+07 Polygon: x = 5.12064e+07 y = -146302 x = 5.12064e+07 y = -146303 x = 5.12064e+07 y = -146305 x = 5.12064e+07 y = -146306 x = 8127 y = -146306 x = 8126 y = -146305 x = 8126 y = -146303 x = 8127 y = -146302 x = 5.12064e+07 y = -146302 POLYGON((8126 3.18455e+07,8127 3.18455e+07,8129 3.18455e+07,8130 3.18455e+07,8130 -146305,8129 -146306,8127 -146306,8126 -146305,8126 3.18455e+07)) POLYGON((5.12064e+07 -146302,5.12064e+07 -146303,5.12064e+07 -146305,5.12064e+07 -146306,8127 -146306,8126 -146305,8126 -146303,8127 -146302,5.12064e+07 -146302)) </p> <p> result count = 2 </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/10866 Trac 1.4.3 Barend Gehrels Wed, 23 Mar 2016 16:00:24 GMT https://svn.boost.org/trac10/ticket/10866#comment:1 https://svn.boost.org/trac10/ticket/10866#comment:1 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">fixed</span> </li> <li><strong>milestone</strong> <span class="trac-field-old">To Be Determined</span> → <span class="trac-field-new">Boost 1.61.0</span> </li> </ul> <p> Thanks for the report, it is fixed in 1.61 </p> Ticket