In ArcMap 10.2, I am trying to render a shapefile with polygons in the Pacific Ocean, which span the 180-degree line. The resulting image shows a line going through the polygons at the meridian, and I would like to know how to avoid this. Note: the polygons are not split into separate features in the attribute table, they are simply rendered with a line through them.

My basemap is in WGS_1984_PDC_Mercator coordinate system, with Central_Meridian: 150.0, so as to depict the Pacific Ocean in one piece (rather than split on opposite sides of the map). I've tried projecting the polygon shapefile into WGS_1984_PDC_Mercator, as I understand this is a Pacific-centered projection. However, this does not get rid of the line.

Want to get rid of vertical line through polygons at 180-degrees

enter image description here

  • Does "they are simply rendered with a line through them" mean these are multipart polygons, one part is on the left hand side and the other is on the right? If so, you can try Dissolve after the projection. – fatih_dur Mar 21 '18 at 1:13
  • Thank you for your response. However, the problem remains. I tried Dissolve, and it melded all the polygons together, but the line is still there. – wgoodell Mar 21 '18 at 1:40
  • What do you see on this line when you zoom in to, say, 1:1 scale? – fatih_dur Mar 21 '18 at 2:45
  • It looks like a line... fatter. : / (see added tri-panel image of diff. scales in post) – wgoodell Mar 21 '18 at 7:51
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    From this information, in fact, the part seen as line is a gap (around 500 metres) between your polygons. Without mending this, it is not possible to have what you are after. Have a look at Integrate tool. I think 510 metres tolerance will fix this. Please be aware that Integrate modifies the original input, so testing the tool on a copy would be beneficial. Also some of your other features might change. – fatih_dur Mar 21 '18 at 7:57

Yes! With help from @fatih_dur in comments, I was able to use the Integrate tool, with a 500+ m tolerance, to resolve a small gap between the polygons.

enter image description here

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  • For reference, the best way to thank someone for assiting you is to ask them to write an Answer, so they can receive reputation points. You can use the "at" symbol as a prefix to reference an SE username. Knowing that there's a gap along the antimeridian, it might be possible to process the affected multi-part polygons with a less drastic tool than Integrate to preserve data fidelity on the unaffected geometries. – Vince Mar 21 '18 at 9:41
  • Thank you! I was actually wondering how to indicate that @fatih_dur was the provider of the answer. I would happy if they would like to provide their final comment as an Answer! – wgoodell Mar 22 '18 at 9:53

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