<div dir="ltr"><div>Hi.<br><br>I have a question about the QGIS algorithm to calculate the lines that cross the antimeridian.<br>Looking at the code I see that it uses the value 120 or -120 to know if we're going west or the east.</div><div><a href="https://github.com/qgis/QGIS/blob/cdc9a841c9caf308d24448597dfa8a2aea48fac3/src/core/qgsdistancearea.cpp#L464">https://github.com/qgis/QGIS/blob/cdc9a841c9caf308d24448597dfa8a2aea48fac3/src/core/qgsdistancearea.cpp#L464</a><br></div><div><br></div><div> I think this algorithm is based on qgis-shapetools-plugin which also uses that value.<br><br><a href="https://github.com/NationalSecurityAgency/qgis-shapetools-plugin/blob/master/utils.py#L43">https://github.com/NationalSecurityAgency/qgis-shapetools-plugin/blob/master/utils.py#L43</a></div><div><br>My question is, why 120 degrees? Why is that value used and not another one like 170 for example?<br>Is this algorithm based on any paper? Is there any documentation?<br>On the other hand, is there any paper, or implementation to calculate the lines that cross the poles?<br><br>thanks and regards<br></div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><font size="1"><b>Francisco Raga</b></font><b style="font-size:x-small"> | </b><span style="font-size:x-small">Full-Stack </span><span style="font-size:x-small">Open Source </span><span style="font-size:x-small">GIS Developer </span></div><div><span style="font-size:x-small">    </span></div><div><font size="1">Móvil: (+34) 654275432<b> | </b>e-Mail: <a href="mailto:franka1986@gmail.com" target="_blank">franka1986@gmail.com</a> <b>| </b>skype: francisco_raga<br>Github: <a href="https://goo.gl/ydNTjY" target="_blank">https://goo.gl/ydNTjY</a></font><span style="font-size:x-small"> </span><b><span style="font-size:x-small">|</span><span style="font-size:x-small"> </span></b><span style="font-size:x-small">Linkedin: </span><a href="https://goo.gl/TCfj8S" style="font-size:x-small" target="_blank">https://goo.gl/TCfj8S</a><span style="font-size:x-small"> </span><b><span style="font-size:x-small">|</span><span style="font-size:x-small"> </span></b><span style="font-size:x-small">Site: </span><a href="https://goo.gl/qiypDj" style="font-size:x-small" target="_blank">https://goo.gl/qiypDj</a></div><div><font size="1"><br>"La vida real no tiene ningún mapa.."  Ivy Compton Burnett</font></div></div></div></div></div></div></div></div></div></div></div>