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I downloaded Natural Earth Ocean Data http://www.naturalearthdata.com/downloads/10m-physical-vectors/10m-ocean/ and tried to reproject by saving the layer as different name and CRS using QGIS

enter image description here

Then, it gives me weird looking shapefile:

enter image description here

Also, America continent and South Asia's land areas are filled.

enter image description here

Using ArcMap, it's totally fine. I am just curious why it happens.

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The Oceans layer extends to the North Pole and so goes to infinity when reprojected to any Mercator projection. If you clip the layer at 85N you should have no problem.

I suspect that ArcMap does this quietly behind the scenes while QGis trusts you to know what you are doing.

  • do you know why it has to be 85N? and there's no limit latitude to South? – Pil Kwon Oct 18 '17 at 9:37
  • there is less ocean in the south - normally you would clip at +/-85 – Ian Turton Oct 18 '17 at 9:38
  • 85 is a pragmatic choice, technically it only goes to infinity at 90 but the numbers get quite big above 85 – Ian Turton Oct 18 '17 at 9:39
  • Thank you so much for your comments! it helped me a lot :) though what would be the exact coordinates to clip my layer by extent? I used -180, 180, -90, 85 – Pil Kwon Oct 18 '17 at 9:40
  • in general, I would use -180,180, -85,85 but with Antarctica/oceans you could leave south pole unclipped – Ian Turton Oct 18 '17 at 9:41

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