Linked Questions

3
votes
1answer
2k views

matching a border of one polygon to another [duplicate]

I have a polygon (A) that I drew the eastern border of in QGIS. I have another polygon(B) whose western border I want to nest against the eastern border of polygon a so they are touching but not ...
2
votes
1answer
393 views

Merging seemingly contiguous polygons leaves artifacts [duplicate]

I am working with a NaturalEarth country vector dataset (download it here) and I am trying to merge country polygons according to custom regions (based on the UN Geoscheme), in order to only have an ...
2
votes
2answers
164 views

Dissolving creates fragments in the middle [duplicate]

When dissolving a polygon shapefile I get fragments in the middle (see pictures) in Qgis and R using the functions from rgeos. Has anybody an idea where this comes from and what can be done to deal ...
1
vote
0answers
76 views

How can I merge overlapping nodes of a polygon in QGIS? [duplicate]

My shape is composed of 7 polygons which are supposed to be adjacent (ie sharing sharing same nodes). Would like to join the polygons by their nodes and make sure there is no space in between two ...
19
votes
5answers
3k views

Algorithm to fix topological errors in GIS software apps

Related question here. I notice that ensuring topological correctness is essential for GIS applications, this is because the input from user or polygon boolean operation can have severe topological ...
11
votes
3answers
511 views

How to improve drawn shapes in Quantum-GIS?

I have a polygon-shape in qgis-1.7.0 and want to fix overlays and gaps between the edges of adjacent polygons. See image below. Is there any automated way to do this in quantum-gis? Or any other F/...
4
votes
2answers
5k views

Create a single connected polygon from multiple polygons

I am trying to create a single continuous (neighborhood) polygon from many tax block parcels. The Multipart to Singlepart GP tool does not accomplish the task since I need the polygon to be complete; ...
4
votes
3answers
3k views

Batch fix overlap errors

I have a feature class with about 250,000 contiguous polygons. ArcEditor turns up around 9,000 overlap errors when I validate the topology. I want to merge each of these errors into one of the ...
3
votes
2answers
837 views

Avoiding/getting rid of topological errors after dissolve?

After dissolving a layer in QGIS 2.8, I get a lot of topological errors in the new (dissolved) layer. Any suggestions as to how to get rid of these errors without manually editing each one? update: ...
7
votes
1answer
533 views

Dissolved polygon shows 'ghost' of previous 'child' boundaries

I dissolved the polygons specifically to get a unified outline without any interior boundaries showing. Now I've got a partially broken interior line within the polygon. This is for cartographic ...
1
vote
3answers
2k views

Removing Slivers/Holes From Polygons using ArcGIS for Desktop?

I have a village level shapefile. Using Dissolve_management, I collapse the villages to district level. I also use Multi_Part option to prevent multiple entries for same polygon and so the resulting ...
3
votes
1answer
1k views

Extracting border between contiguous polygons using ArcGIS for Desktop?

I have a shapefile with polygons representing unique populations. I want to determine contiguous polygons in my shapefile, and then extract the border separating contiguous polygons as a separate ...
1
vote
1answer
514 views

Identifying differences in polygons across shape files

I am trying to compare the 2000 Census county boundaries with the 2010 Census county boundaries. Each county is uniquely identified in a given year by a FIPS code and I want to compare if the polygon ...
2
votes
0answers
653 views

Eliminate sliver polygons, not the enclaves

I would like to use the 'Eliminate sliver polygons' in QGIS, but only if they have the same attributes. To be more specific, I have an administrative shapefile that was created with the SEXTANTE tool ...
1
vote
2answers
246 views

ST_Union doesn't completely dissolve boundaries of adjacent polygons with CurvePolygon

Starting from this set of geometries: I need to achieve this result (from ArcMap's Dissolve algorithm): But what I get from PostGIS is this: Here is the query I use: SELECT (ROW_NUMBER() OVER())::...

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