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I'm not sure how to remove the line that represents the 180th meridian (international dateline) on my polygon. I have the "Russia Country Boundary 2017" feature layer added from the Living Atlas. My Projected Coordinate System is set to "Asia North Albers Equal Area Conic". I've tried to google this question, but I haven't come across an answer I can fully understand. I'm a student and very new to all this!

The line is actually a gap between the polygons. enter image description here

Using ArcGIS Pro 2.3.1

ANSWER:

It turns out I was not projecting correctly, which was creating issues down the line when editing polygons. Here's what I did...

1. Start a blank project in ArcGIS. Insert new map, go into its properties, change the Coordinate System to "Asia North Albers Equal Area Conic".

2. Add "World Countries (Generalized)" from the Living Atlas. Select Russia and Export Features to new feature class layer.

3. Search and select the Project tool from Analysis>Geoprocessing>Tools.

4. Select the Russia layer for input. Select "Current Map" for Output Coordinate System. Run.

5.Now edit the polygons to close the gap and merge to remove any lines. All done!

The only thing that bothers me with this fix is the addition of shape area (484,914.49674 m²) and shape length (4.59 m) to the original Russia polygon. These numbers could be different depending on how you close the gap, and possibly affect data projections depending on your use of this map?

  • Please only provide answers in the area reserved for answers. Only your question should appear in this area which is reserved for questions. – PolyGeo Mar 21 at 21:53
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Note, that feature class is one multipolygon comprised of 839 polygons. If you run the multipart to singlepart tool, you'll see that.

Anyway, the simplest way is to just turn off the border in the layer symbology:

enter image description here

Dissolving or merging would also work IF those two polygons were adjacent, however there is actually a slight gap. So you would have to:

  • Project the feature class to "Asia North Albers Equal Area Conic", it won't work if you leave the data in WGS84 geographic (EPSG:4326) coordinates.
  • Edit the vertices of the projected feature class polygon
  • Drag the two vertices at either end of the dateline so they snap to the larger polygon
  • Click merge (in the Edit toolset of the ribbon).

enter image description here enter image description here enter image description here

  • Anytime I move the vertices or polygon over the date line to connect with the other side, the gap will reappear – JoshALogs Mar 20 at 20:15
  • Did you project the feature class? You need to do this using the Project tool to actually change the underlying coordinates of the data, not just by changing the CRS of the map. – user2856 Mar 20 at 20:20
  • I got it! turns out I was projecting on the fly, and not using the appropriate Projection tool. Thanks! – JoshALogs Mar 21 at 17:31
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It looks like you have two polygons, with the edge along meridian. Use 'dissolve' to make two polygons into one.

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Merge existing features in ArcGIS Pro

To modify existing features on the same layer and merge them into one feature, click Merge, click Existing Feature, and select the features. In the pane, click the feature containing the attributes you want to preserve, and click Merge.

  1. On the Edit tab in the Features group, click Modify Modify Features. The Modify Features pane appears.
  2. Expand Construct and click Merge Merge. The tool opens in the pane.
  3. Click Existing Feature.
  4. Click Select Select and select two or more polyline or polygon features on the same layer. The selected features appear as a list in the pane.
  5. If you select features on more than one layer, click the Layer drop-down arrow and choose a layer.
  6. In the Features to Merge list, do the following:

    --Click the feature containing the attributes you want to preserve.
    --To remove a feature from the selection, click Delete Delete.
    
  7. In the Merged Feature Attributes table, edit the attribute values you want to apply to the new feature.

  8. Click Merge. The features are merged into one feature.

  • I don't think I can merge anything. There is only one polygon in this feature layer. If you look at the picture, there's only one row in the attribute table. – JoshALogs Mar 18 at 18:56
  • Just delete the vertices in this location then (the join location). – If you do not know- just GIS Mar 18 at 18:59
  • How would I edit vertices? I go to Edit>Modify>Vertices, select the polygon, but no vertices appear. – JoshALogs Mar 18 at 19:07
  • Then you should be able to view them and right click to delete them assuming you selected the polygon – If you do not know- just GIS Mar 18 at 20:33
  • The polygons aren't adjacent, there's a slight gap so merge won't work until the polys have been snapped together.. – user2856 Mar 19 at 1:45

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