How to join lines in QGIS for later using "lines to poly"?

Question

After successfully merging lines (using snapping) with merge_selected_features i got nice result - one merged line. Next thing was to make polygon from created merged line. Result is not nice - it creates multiple polygons connecting ends from separate lines which were merged previously together. Somehow merging geometry is not working for me or i am missing something.

.. Solved. I imported lines in Grass, then i used v.build.polylines and got nice line from which i was able to create correct polygon.

Instead of editing the title to include "Solved", please accept an answer. If there is no suitable answer, you can write one yourself. — underdark, Aug 24 '12 at 09:35
It should have worked. I have tested it in QGIS 1.8 in windows vista, and the merge_features --> Lines to Polygons sequence worked well. — Alexandre Neto, Aug 24 '12 at 14:36

score 1 · Answer 1 · answered Aug 24 '12 at 08:21

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I should try using the Polygoniser plug-in. You shouldn't need to merge the lines to use this. See: http://confound.me.uk/maps/ppv4.pdf

Nick.

answered Aug 24 '12 at 08:21

nhopton

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Testing right now. New version went to 55% and old version - to 95%; both didnt work, it freezed and stopped QGIS. – Didzis Aug 24 '12 at 08:50
Pleased to hear that you've got around the problem. For the record, to work the polygonizer plug-in needs the python-shapely package to be installed. N. – nhopton Aug 24 '12 at 09:05
will try with OSGeo4W. previously tried with installed QGIS version and i guess without that shapely lib. – Didzis Aug 24 '12 at 09:20

score 0 · Answer 2 · answered Nov 30 '12 at 04:35

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Isn't this a result of the lines being different directions? I believe it should work if all the joined lines are in the same direction & then reindexed so that the node numbers are in the proper sequence.

answered Nov 30 '12 at 04:35

jeffme

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How to join lines in QGIS for later using "lines to poly"?

2 Answers2

Linked