I'm a new QGIS user. I'm trying to convert a polyline vector layer to polygon. I tried to it in ArcMap 10.1 but it misses a lot of polygons. So, I'm attempting to this in QGIS running the process "Lines to Polygons". However, when I load my shapefile into QGIS, it doesnt' display well. Only half of my map and some random spots are shown (I also noticed that in QGIS the attribute tables has way less lines). I attach two screenshots from the same layer in ArcMap and QGIS. Thanks in advance,


In Arc In QGIS


Converting polylines to polygons is not as straight forward operation as it may seem. The "polyline layer" in your example looks to be EXTREMELY complex. The only way for any polyline to polygon operation will succeed is if the all polylines are closed and simple. If there are any dangling lines, duplicate path segments or polylines that are not closed then a polygon will not be created.

Ensure all polylines are simple and closed and try again.

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  • Hi Jakub, thanks for your answer. But the problem I have now is not the transformation to polygon but rather that QGIS is not displaying the shapefile lines layer correctly . – 1buzz Dec 3 '13 at 21:10
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    Still possibly a result of the failed conversion or invalid geometry. Screen renderers ArcGIS or QGIS alike will fail to draw - if the renderer can't resolve the geometry, it won't be able to draw it. The problem is still likely the source data and the resulting conversion of polyines to polygons. To troubleshoot - find one polyline that doesn't draw/convert then identify problems. ArcInfo has some tools to automate this. There are many possibilities but I would recommend to start with the source data. This problem is not specific enough to provide a single solution. – Jakub Sisak GeoGraphics Dec 3 '13 at 21:24
  • Check geometry problems on the layer. Since you have access to ArcGIS you can do it using the Toolbox from Data Management Tools, Features, Check Geoemetry and check out its results, then you can run Repair Geometry. See if that helps – Antonio Locandro Dec 5 '13 at 20:05
  • You can delete the spatial index files .sbn .sbx or rebuild them. – klewis Feb 25 '14 at 13:54

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