Is there a way to apply topological editing to move vertices between two coincident features that are not in the same layer?

For example, if I have a crop land polygon coincident with a soil polygon (from a crop layer and a soil layer) and I want to reshape the border between the two using the node tool, is that possible without moving a vertex in crop, changing to editing soil, and moving the vertex to be coincident with crop?

What if there is a line road coincident with the edge of a polygon (i.e. a polyline layer rather than a polygon layer), again can I reshape the two at once?

I am aware of the topological editing, but that appears to only work between two polygons of the same layer.


1 Answer 1

  1. You can copy one layer to the other layer (let's say all soil polygons to the crop layer): select all features on soil layer, use Menu Edit/ Copy features, then go to the crop layer, toggle editing mode, Menu Edit / Paste features

  2. The inserted features are selected. Use this selection to create a new attribute called layer to distinguish the polygons by the initial layers they come from. Be sure you have checked Only update N selected features and add an attribute with value soil (if you want, you can then invert the selection to name the remaing features as crop, but that is optional).

  3. Use Categorized styles with different colors based on the layer attribute to see which polygons belong to which one of the initial layers.

  4. Then do the snapping/topological editing.

  5. When done, use select by expression, select all the polygons that belong to the soil layer with layer='soil' and export these features as a new soil layer. You can then delete the soil polygons from the layer so that it only remains with the crop polygons.

  • 1
    A classic workaround. That's something I've done in a much cruder fashion just to test it out. In most cases I'd just edit each layer. I noticed that at least In 3.22 you can put both layers into edit mode, turn on topological editing, and if you try to select both polys only one gets selected but you can then can move a shared vertice of the selected layer "out" from it and the shared vertice of the other layer will move with it at the same time. I'll have to explore this more later. I'll note the reshape tool only acted on the selected layer.
    – John
    Nov 3, 2021 at 14:02

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