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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>You could also try using ST_Polygon<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>It will treat all non NA as the same resulting in a polygon or multipolygon.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><a href="https://postgis.net/docs/RT_ST_Polygon.html">https://postgis.net/docs/RT_ST_Polygon.html</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><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;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> postgis-users [mailto:postgis-users-bounces@lists.osgeo.org] <b>On Behalf Of </b>Marcin Mionskowski<br><b>Sent:</b> Tuesday, January 11, 2022 12:43 AM<br><b>To:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br><b>Subject:</b> Re: [postgis-users] Postgis Raster determine exact hull<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal><span style='font-family:"Courier New"'>Hi,<o:p></o:p></span></p></div><div><p class=MsoNormal><span lang=EN style='font-family:"Courier New"'>Try to reclassify the raster first so that all "non NA" values are equal (e.g. 1), then do ST_DumpAsPolygons</span><code><span lang=EN style='font-size:10.0pt'>.</span></code><span style='font-family:"Courier New"'><o:p></o:p></span></p></div><div><p class=MsoNormal><span lang=EN style='font-family:"Courier New"'>Regards,</span><span style='font-family:"Courier New"'><o:p></o:p></span></p></div><div><p class=MsoNormal><span lang=EN style='font-family:"Courier New"'>Marcin</span><span style='font-family:"Courier New"'><o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>pon., 10 sty 2022 o 21:27 Richard Huesken <<a href="mailto:richard.huesken@gmail.com" target="_blank">richard.huesken@gmail.com</a>> napisał(a):<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><p class=MsoNormal>hi,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'm using postgis 3.1 and I'm looking for the best way to obtain the exact hull of a raster (excluding the nodata points). The st_minconvexhull uses the MBR of the raster coverage, and is therefore quite fast. The result is however not as accurate as I require.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I constructed some sql that uses st_pixelaspolygons and then does a st_union. However, My typical raster has 256x256 points, and with several 100s of rasters this is quite slow.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Are there more clever (and faster!) ways to get the exact hull of a raster?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks in advance,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Richard.<o:p></o:p></p></div></div><p class=MsoNormal>_______________________________________________<br>postgis-users mailing list<br><a href="mailto:postgis-users@lists.osgeo.org" target="_blank">postgis-users@lists.osgeo.org</a><br><a href="https://lists.osgeo.org/mailman/listinfo/postgis-users" target="_blank">https://lists.osgeo.org/mailman/listinfo/postgis-users</a><o:p></o:p></p></blockquote></div></div></div></body></html>