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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'>David,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>There are some examples in the manual. There is a ST_ConcaveHull function and an ST_AlphaShape. Both do essentially the same thing but use different engines.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Part of postgis extension, uses GEOS under the hood<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><a href="https://postgis.net/docs/en/ST_ConcaveHull.html">https://postgis.net/docs/en/ST_ConcaveHull.html</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Part of postgis_sfcgal – uses CGAL under the hood.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>The ST_AlphaShape one is only available if you have postgis_sfcgal extension installed.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><a href="https://postgis.net/docs/en/ST_AlphaShape.html">https://postgis.net/docs/en/ST_AlphaShape.html</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>To Barend,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Thanks for your consideration of our time, but I think it’s better for people to not fear asking questions and worry the question they are asking is something they should have looked up in the manual. I’d rather they ask, and we point them to the section of the manual where it is detailed.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>This mailing list isn’t so crowded that we can’t simply ignore questions we’d rather not bother answering. David asks very useful questions that I think a lot of people could benefit from searching our mail list archives for and that to me is a great contribution, so please don’t discourage him.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Regina<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt'>From:</span></b><span style='font-size:11.0pt'> postgis-users <postgis-users-bounces@lists.osgeo.org> <b>On Behalf Of </b>Kobben, Barend (UT-ITC) via postgis-users<br><b>Sent:</b> Friday, September 8, 2023 9:57 AM<br><b>To:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br><b>Cc:</b> Kobben, Barend (UT-ITC) <b.j.kobben@utwente.nl><br><b>Subject:</b> Re: [postgis-users] Is there a simple way to generate polygon from random points?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Georgia",serif'>Really Shaozhong Shi (David)...? After all these years of open questions without any focus you cannot even lookup the functions the respondent mentioned yourself, in the excellent PostGIS manual...?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Georgia",serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Georgia",serif'>Please have some consideration for the people putting in their time to help others. RTFM.<o:p></o:p></span></p><div><p class=MsoNormal><i><span style='font-family:"Georgia",serif;color:black'>-- <o:p></o:p></span></i></p><p class=MsoNormal><i><span style='font-family:"Georgia",serif;color:black'>Barend Köbben<o:p></o:p></span></i></p></div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Georgia",serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Georgia",serif'><o:p> </o:p></span></p><div id=mail-editor-reference-message-container><div><div><p class=MsoNormal><span style='font-size:11.0pt'>On 08/09/2023, 15:37, "postgis-users" <<a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a>> wrote:<o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt'><br>Is there a sample script?<o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:11.0pt'>Regards</span><span style='font-size:11.0pt;font-family:"MS Gothic"'>，</span><span style='font-size:11.0pt'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:11.0pt'>David<br><br>On Friday, 8 September 2023, Erik Wienhold <<a href="mailto:ewie@ewie.name">ewie@ewie.name</a>> wrote:<o:p></o:p></span></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal><span style='font-size:11.0pt'>On 08/09/2023 13:34 CEST Shaozhong SHI <<a href="mailto:shishaozhong@gmail.com">shishaozhong@gmail.com</a>> wrote:<br><br>> Is there a simple way to generate polygon from random points?<br><br>Compute the convex or concave hull or an alpha shape. PostGIS provides<br>functions for all three of them.<br><br>--<br>Erik<o:p></o:p></span></p></blockquote></div></div></div></div></div></body></html>