3

I am currently trying to digitize FEMA flood panels and I was wondering if anyone knows how to duplicate existing polygons within QGIS. Specifically I am trying to have identical rectangular polygons adjacent to this one.

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2 Answers 2

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Slightly misleading title.

But @ahmadhanb is correct, you can create an identical polygon by copying/pasting. However, what you want is an adjacent polygon of the same dimensions (just not the same locations). In which case, I propose two options:

1 - when editing a feature, the ability to move a feature exists. Create the duplicate and then move it. Snapping also exists, which could be helpful.

2 - you can automatically create a grid, under Vector - Research Tools - Create Grid. Experiment with options here to automatically create a grid of polygons adjacent to each other.

A polygon is made up of points, and each point is defined as a location (with a x/y and sometimes z coordinate). A duplicate polygon would be one in the same location, so what you want is a polygon of the same size and orientation.

2

An option using the Geometry by expression tool:

collect_geometries(
    $geometry, 
    translate(
        geometry:=$geometry,
        dx:=bounds_width($geometry), 
        dy:=0
    )
)

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If you want identical rectangular polygons covering an area, your best bet is probably the Create grid tool. Vector > Research tools > Create grid (or Processing toolbox > Vector Creation > Create Grid). You can set an extent for the grid, and a width and height for the cells.

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