I'm working on a simple polygon feature representing the Western Cape province of South Africa. My goal is to enlarge the polygon so it can stand out from the others.

To do so I've used the v.transform tool, but the output layer is empty. The picture below shows how I've computed the tool, I might be doing something wrong. enter image description here

As I understand it:

X shift: I've put the x coordinate of the centroid of the polygon.

Y shift: same for the y coordinate

X scale: the factor by which I'd like to enlarge my polygon (I've used 130% for the example, according to another post: How to resize shapefile features proportionally in QGIS?)

GRASS GIS 7 region: my canvas extent.

  • 2
    Shift = move somewhere else. Also, I do not know, whether shift and extent may be based on different units.
    – Erik
    Feb 12, 2020 at 11:16
  • The only issue is that I do not how to do this on a shapefile with multiple polygons
    – Tim56
    Feb 12, 2020 at 11:34

1 Answer 1


I found a way. I shifted from using the GRASS tool to the SAGA tool "transform vector layer". The wizard is simpler and easily computable:

enter image description here

dX: I left the default O

dY: same

Angle: 0

Scale factor X: factor by which you want to enlarge it: 1,3 will enlarge by 130%

Scale factor Y: same

X: centroid X of polygon

Y: same for Y

  • You mixed the fields! dX - your X coordinates dY - your Y coordinates X - left 0 Y - left 0
    – Geographos
    Aug 12, 2020 at 16:14

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