QGIS – Removing Overlapping Polygon Boundaries Within Same Layer

Question

We are building mosaic datasets for 100's of rasters (Topo sheets). Used QGIS Tile_Index to get the raster_topo_sheet's extent as vector. But the issue is, overlaps near the edges of all the topo sheets. Instead of manually correcting these edges for footprint creation, can't we merge/delete one boundary and make it seamless ?

1) Tried "Eliminate selected polygons" in qgis with alternate polygons selected (Largest common boundary). But result was not as expected.

2) Tried "Dissolve tool" in QGIS. Removing overlapping/duplicate polygons in same layer using QGIS?. But same overlap exists.

Answer 1

QGIS 3.4.1

From Processing Toolbox:

1. SAGA | Vector polygon tools - Polygon self-intersection tool. This tool returns a new layer with sub-divided polygons (while only one of the duplicated overlapping area is retained).
2. Vector selection - Select by expression tool. Use an expression to select the sliver polygons (see below example).
3. Vector geometry - Eliminate selected polygons tool will remove these selected features. (I would suggest Largest common boundary option... it will give more naturally-looking output.)

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(Example of the Step 2) It is hard to explain the Step 2 without showing sample pictures...

Use Select by Expression on the Intersection layer (output layer by the Step 1) to select sliver polygons. In this example I selected polygons which area are less than 7,000 m2. (Please decide this threshold value beforehand. I used Measure Area tool and visually checked the biggest sliver I wanted to remove.)

All slivers were successfully selected and highlighted, so I can merge them with the neighbor polygons.