I am trying to edit the geometry of one polygon to match another polygon, same as in this question:

Snapping polygons while reshaping edges?

Unfortunately, using the Reshape and Trace editing tools is achingly slow and tedious and I have a bunch of locations spread across a bunch of polygons that require this editing. I also tried the Enable Tracing tool in QGIS as this thread suggests: Adjust polygons by edition (freehand and reshape tools used together) to no avail.

Are there any other approaches that have worked for others to do this efficiently?

Just doing a rough reshape and then clipping or erasing (as suggested in the first thread) gets complicated since the lines intersect in both directions (see image). I want to align the low-res black polygon to the high-res blue polygon in specific places.

enter image description here

  • 1
    You could try to run simplify geometries on the high-res polygon.
    – Erik
    Commented Jan 26, 2021 at 15:14
  • Removed tag for ArcGIS Desktop to focus question on QGIS. Feel free to ask a separate question about ArcGIS Pro or ArcMap.
    – PolyGeo
    Commented Jan 26, 2021 at 20:14
  • Is the black polygon a crude match in extent to the blue polygon or is it a crude fill of the hole in the blue polygon?
    – John
    Commented Jan 26, 2021 at 20:37
  • They are distinct layers... the black line polygon representing a unique aquatic ecological area and the blue polygon representing a high-res coastline. Both polygons showing marine areas (the white being land).
    – mikeLdub
    Commented Jan 26, 2021 at 21:13
  • 1
    This looks like a datum transformation shift.
    – Vince
    Commented Jan 26, 2021 at 23:47

2 Answers 2


Turn the question around. Instead of trying to reshape the simple polygon to match the detailed polygon, create a copy of the detailed polygon and inherit the attributes of the simple polygon using a spatial join.

QGIS methodology:

In the Processing Toolbox use the Vectory general > Join attributes by location tool using the following parameters:

  • Base layer - complex polygon
  • Join Layer - simple polygon
  • Fields to add - Whichever attributes you want the new dataset to inherit from the simple polygons
  • Discard records which could not be joined - checked

Everything else you can leave as default.

Open the attribute table of the new dataset and delete the fields from the original complex polygon.


First of all I think the root problem is a transformation shift like mentioned in the comments.

But regarding your question: The easiest way to solve this issue is to use a plugin called Plain Geometry Editor. First you have to select the source geometry, copy the WKT string and then select the target geometry and paste it there.

Plain Geometry Editor

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