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I'm relatively new to GIS, and I'm currently using QGIS version 3.32.3 Lima. I'm encountering some challenges as I don't have a solid foundation in using GIS, so I'm reaching out for your help and understanding. My current project involves creating a map for the African penguin colony in the Stony Point Nature Reserve in Betty's Bay, South Africa. To achieve this, I've been using the QuickMapService plugin with the Google Satellite coordinate EPSG 3857. After zooming in on the specific area, I created a new shapefile layer, opting for the polygon type with EPSG 3857. Following that, I went to Visualize > Decoration > Grid and generated a grid with a side length of 25x25.

Now, my next step is to obtain the GPS coordinates of the center of each square. Could someone provide guidance on how I can accomplish this?

Additionally, if you have any suggestions for more solid and useful procedures, I'm open to your insights.

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There are many ways of doing this but for a new user I would suggest the following Use the regular grid tool (Top menu>Vector>Research Tools> Regular Grid) to create your survey grid. This can be restricted to the extents of the map canvas or your survey polygon. If you specify EPSG 3857 as your output you can set the point spacing in meters This can be a temporary layer. Regular grid

Once you have your grid you can delete any unwanted points etc then re-project it to EPSG 4326 for GPS (Top menu>Vector>Data Management Tools> Reproject Layer). enter image description here Then you need to get the coordinates - In the attribute table calculate new columns for Lon and Lat using $X and $Y

Caluclate X

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  • Thank you for your fast response, @Sethinacan! It's functioning as expected! I've created the grid and centroids for the square as you suggested. However, I have a couple of follow-up questions: Why is it necessary to re-project the centroids? How can I visualize only the centroids within my polygon? Currently, the grid is a rectangle that covers the entire polygon area.
    – fterranova
    Jan 9 at 15:14
  • Reprojection - so that when you calculate the lat and lon you get values in the right projection, there other ways of doing this. Only the centroids in your polygon - delete the others is the easiest way, you can use select by location if that helps or use select features by polygon
    – Sethinacan
    Jan 9 at 15:22
  • Thanks very much @sethinacan, following your suggestions I was able to obtain grid and coordinates centroids!
    – fterranova
    Jan 10 at 15:26

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