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I am using ArcGIS 9.3/10 to dissolve few hundreds of overlapping polygon features. Now, I am seeing that Arcgis is not able to do dissolve for 5000 polygons. Generally, I used to dissolve (unchecked create multipart features) in arcgis based on geometry not with any dissolve fields.

I am trying with QGIS version -1.8.0-Lisboa dissolve tool for that 5000 polygons, here it is mandatory to select any one of the dissolve field. note: there is no common field to group the polygons. I selected dissolve, but it generated ONE polygon (with multiparts)..

I need multiple dissolved polygons based on the overlap of the polygons in the input file.

How to do this in QGIS or any other open source available, (since arcgis is not able to do)

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A quick solution would be to run Multipart to Singlepart after the initial Dissolve operation (found under Vector -> Geometry Tools -> Multipart to Singlepart)

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Hi, I tried the dissolve (with field selected Dissolve all).. it created one polygon. as you suggested i ran multipart to single part, it gave me the output which is as similar to my input file. – vadivelan Jul 25 '12 at 23:14

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