I cannot find an answer to this question, not even in the official QGIS documentation. Here is the problem:

First, I delineate a survey area layer (geometry type is polygon):

survey area polygon

When I create a grid (using the "Create grid" tool) with the grid type "Rectangle (Polygon)", which is calculated from the extent of the survey area layer, I get this:

polygon-type grid

When I create a point grid that is calculated from the extent of the same layer, I get a slightly different result:

point-type grid

To get the points I need and to use them for stacking with a GNSS unit, I have to use the "Extract vertices" tool to create a new point layer calculated from the polygon grid:

point grid after using "extract vertices" tool

It's not a big deal, but I'm still curious why there's a difference in the extent of the "point" type grid and the "polygon" type grid. Is there any official documentation on this topic?

  • Probably because the grid is bigger than the actual polygon extent so some vertex of your grid are outside of the polygon extent. in the other hand when creating a point grid point are only placed inside the extend
    – J.R
    Jan 30 at 15:40

1 Answer 1


I'm not sure it answers the question of why, but the official documentation is pretty clear that the extent of a polygon grid is larger than the extent of the corresponding point or line grid.

enter image description here


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