I have two shapefiles. One is broken into the regions I need to use, the other has much more detail along the coast line. I'd like to use either intersect or clip to get a more detailed coastline on the eastern edge of the map, but I wind up with a blank layer with both.

With vector > geoprocessing tools > intersect the new layer is empty no matter how I arrange the settings. If I use vector > geoprocessing tools > clip and put the big unified polygon as the "input vector" I wind up with the opposite of what I want -- a new layer that has one big polygon and no coastal detail. What I want is a layer of small polygons with coastal detail. What am I doing wrong here?

I'm working in QGIS, though if this would be easier to do in PostGIS I can also use CartoDB.

broken into regions one big poygon

  • Try using Union (Vector > Geoprocessing Tools > Union), this combines the two layers along with their attributes so you should get both the regions and the coastal lines. – Joseph Nov 16 '15 at 10:44
  • The problem is that on the East side, the regions extend past the coastal line. – Amanda Nov 16 '15 at 17:59
  • Most likely either the two layers do not have the same CRS or there is an invalid geometry. – underdark Dec 8 '16 at 18:50
  • Sadly, I can't test the answers anymore. – Amanda Dec 8 '16 at 23:01

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