<div dir="ltr"><div dir="ltr"><div>How about each line gets split into segments. <span style="font-family:Calibri,sans-serif;font-size:11pt">. Each segment
is constructed with two points (current and next points.</span></div><div>Then, calculate bearing/azimuth</div><div>Then, determine whether it is clockwise or counter-clockwise.</div><div><br></div><div>Can this be done?</div><div><br></div><div>Regards,</div><div><br></div><div>David</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 16 Feb 2022 at 20:39, Marcin Mionskowski <<a href="mailto:mionskowskimarcin@gmail.com">mionskowskimarcin@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div style="font-family:monospace"><span lang="en"><span><span>It doesn't make sense for lines.</span></span></span></div><div style="font-family:monospace"><span lang="en"><span><span>Imagine LINESTRING(1 0,1 1) - which "part of a square" is this i.e. where is "the center of the <span lang="en"><span><span>square</span></span></span>": (1) 0.5,0.5 or (2) 1.5,0.5?</span></span></span></div><div style="font-family:monospace"><span lang="en"><span><span>If (1) it's CCW, if (2) CW.<br></span></span></span></div><div style="font-family:monospace"><span lang="en"><span><span><br></span></span></span> </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">śr., 16 lut 2022 o 21:29 Shaozhong SHI <<a href="mailto:shishaozhong@gmail.com" target="_blank">shishaozhong@gmail.com</a>> napisał(a):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr">The problem now is that I can not find anything for lines.<div><br></div><div>Anything like <span style="font-family:monospace">ST_IsPolygonCW|ST_</span><span style="font-family:monospace">IsPolygonCCW for lines for instance, something like </span><span style="font-family:monospace">ST_IsLineCW|ST_</span><span style="font-family:monospace">IsLineCCW.</span></div><div><span style="font-family:monospace"><br></span></div><div><font face="monospace">Regards,</font></div><div><font face="monospace"><br></font></div><div><font face="monospace">David</font></div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 16 Feb 2022 at 19:43, Marcin Mionskowski <<a href="mailto:mionskowskimarcin@gmail.com" target="_blank">mionskowskimarcin@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div style="font-family:monospace">Assuming simple polygons, composed from exterior ring only (i.e. no multipolygons), I think that you are looking for a function {ST_IsPolygonCW|ST_IsPolygonCCW}.</div><div style="font-family:monospace"><br></div><div style="font-family:monospace">Greetings,</div><div style="font-family:monospace">Marcin<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">śr., 16 lut 2022 o 19:55 Imre Samu <<a href="mailto:pella.samu@gmail.com" target="_blank">pella.samu@gmail.com</a>> napisał(a):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>> how vertices run? clockwise or anti-clockwise?</div><div><br></div>maybe the:<div><a href="https://postgis.net/docs/ST_Angle.html" target="_blank">https://postgis.net/docs/ST_Angle.html</a> <i>"Computes the clockwise angle between two vectors."</i><br></div><div>or <a href="https://postgis.net/docs/ST_Azimuth.html" target="_blank">https://postgis.net/docs/ST_Azimuth.html</a><br></div><div><br></div><div>regards,</div><div> Imre</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Shaozhong SHI <<a href="mailto:shishaozhong@gmail.com" target="_blank">shishaozhong@gmail.com</a>> ezt írta (időpont: 2022. febr. 16., Sze, 17:06):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr">Can we use PostGIS to find out how vertices run? clockwise or anti-clockwise?</div><div dir="ltr"><br></div><div>Regards,</div><div><br></div><div>David</div></div>
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