Re: [Qgis-user] 200717 - How do I enclose an orthogonal grid of points with a polygon boundary.

[Micha Silver]

On 17/07/2020 8:21, Paul T A Drea wrote: Hello list, I hope this finds everyone safe and healthy during these trying times. I am using a MacBook Pro running macOS 10.15 (Catalina). QGIS version 3.14.0-Pi. QGIS code revision 9f7028fd23. I have a shp file containg 2 653 337 points in an orthononal grid with 25m x 100m spacing of the points. The grid is oriented north south. These points are in lines spaced 25m in the easting (X) direction and 100m northing (Y) direction. I would like to apply a polygon as a boundary (red) as shown in the screen grab below. I have not been able to achieve this using convex hull as the final output does not take into acount the sawtooth steps. Any help or pointers would be appreciated thanks. I am not a coder and have no knowledge of writing any scripts. I believe what you want is a "concave hull". PostGIS has a function for this: https://postgis.net/docs/ST_ConcaveHull.html Also if you want to consider R, you might try the concaveman package: https://github.com/joelgombin/concaveman Thanks and Best regards, Paul -- Paul T. A. Drea Geodetic Consultant Cell Greece: +30-698 052 0611 Cell Abu Dhabi: +971 50 595 6547 Cell U.K.: +44 7507 975162 SKYPE: paul.drea e-mail 1: pauld...@gmail.com e-mail 2: ptad...@otenet.gr    _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user -- Micha Silver Ben Gurion Univ. Sde Boker, Remote Sensing Lab cell: +972-523-665918 https://orcid.org/0000-0002-1128-1325

_______________________________________________
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user