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I did a Land Use Land Cover Classification based on multiple and different source shapefiles. The problem I'm facing in the result now is that there a thousands (about 50.000) of little gaps which I have to dissolve (the pink obejcts within the picture).

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I tried to fix them with topology rules but the problem here is that I have to click through every single gap which is really time consuming and in addition the 'create feature' tool under 'fix' doesn't even work for me here (if I click it nothing happens).

Also I don't want to create a new object within the gaps but I want the gaps to be filled by neighbouring objects that already exist. So e.g. I want one gap to be filled by an already existing object it shares the longest line segment or outer border with. My next idea would be to fix the gaps by a spatial join between the gaps and the Land Use Land Cover Shapefile. But I think this would result in other problems.

Has anyone ever faced the same problem and knows how to automatically fix this problem?

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2 Answers 2

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The following link on ArcGIS website provides you the possibilities for eliminating gaps or slivers.

Removing slivers or gaps between polygons: https://desktop.arcgis.com/en/arcmap/latest/manage-data/editing-fundamentals/removing-slivers-or-gaps-between-polygons.htm

Try out the last solution they mentioned:

You can perform a Select By Attributes query for polygons that have an area smaller than a certain size, depending on your dataset. You can inspect the selected polygons to see if they are slivers, then either use the Editor > Merge command or the Eliminate geoprocessing tool (requires an ArcGIS Desktop Advanced license) to merge the slivers with neighboring polygons. You could also select each polygon individually and reshape the feature by tracing along the edge of the adjacent larger polygon.

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  • It's worth emphasising that the Eliminate tool has a selection parameter that can be set to length.
    – Hornbydd
    Jul 22 at 11:53
  • Thank you really much for your answer! I tested all these tools but unfortunately they didn't work really much. Either they detransform the geometries of the features or it's an manual approach which is too time consuming.
    – Radde1683
    Jul 22 at 12:40
  • Yes, thank you hornbydd, the eliminate tool worked really good!
    – Radde1683
    Jul 22 at 13:03
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I found an automated solution that worked really well if anybody is interested:

  • First I generated a new shapefile of the boundary of my study site. For that I used the 'minimum bounding geometry' tool with my LULC shapefile as the input.
  • Then I used the 'erase' tool and erased my LULC shapefile from my study site to get all the gaps.
  • Then I merged the LULC and my gaps into one single shapefile. Optionally you can also use the 'union' tool and uncheck the 'allow gaps' option.
  • Then I selected all gaps by using a 'selection based on a spatial location' with the merged shapefile (LULC and gaps) as the input feature and the only-gaps shapefile as the selecting feature. For the relationship I choosed the option 'are identical to'.
  • In the last step I used the function 'eliminate' with my merged shapefile as the input, so every selected feature (all the gaps) gets eliminated or dissolved to the unselected object it shares the longest border with.

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