Hi Paul, I don't think you will find a function in QGIS to do this, but you should be able to achieve it by using the following procedure:
1) Create a polygon grid with the same "spacing" as your point grid. Use the "Create grid" algorithm (from the Processing Toolbox), with Grid type: Rectangle (Polygon) Grid extent: Click on the ... pull-down and select "Calculate from layer", and select your point layer Horizontal spacing: 25 meters Vertical spacing: 100 meters 2) Run the "Join attributes by location (summary)" algorithm with Input layer: the generated polygon grid from the first step Join layer: your point grid Geometric predicate: "intersects" 3) Run the algorithm "Select by Attribute" with Input layer: your "Joined layer" (from step two) Selection attribute: one of the *_count attributes Operator: = Value: 4 Modify current selection by: creating new selection 4) Run the "Dissolve" algorithm with Input layer: your "Joined layer" from step 2-3 check "Selected features only" This should work (but rounding errors may cause problems in step two and four) Håvard On 17.07.2020 07:21, 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. > > 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: **[email protected]* <mailto:[email protected]> > > *e**-mail 2: **[email protected]* <mailto:[email protected]> > _______________________________________________ Qgis-user mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
