Esri Mapping Center - Ask a Cartographer

Polylines over the North Pole (ArcMap 10)

November 10 2011 | 2 comments
Categories: Data Modeling, Symbology

When drawing polylines in ArcMap 10 in an Albers Equal Area Conic projection over the north pole (in the center), the lines become distorted and jagged. Is there any way to correct this and simulate the normal "great circle" lines? I'm attempting to illustrate flight plans between North America and northern Eurasia.

Mapping Center Answer:

I am not sure how your data were generated (which may be the source of the problem), but you may want to reconstruct your lines using the XY to Line geoprocessing tool with an origin point, a destination point and specifying geodesic as your line type. This will create new line features between your points following a great circle path.

You might also check out our Creating Radial Flow Maps blog entry on Mapping Center that discussed the construction of these types of maps.

I don't think that is the answer posted by Kainien Morel on Nov 15 2011 12:40PM

Unfortunately, I don't think that is answering my question. My data is a list of locations that I need to draw lines between, not a table. The actual lines, when drawn, are distorted (that is, over the poles they become warped in unpredictable directions before returning to normal). Before I go through the process of creating a table where one is not needed, can I be sure this won't lead to the same problem when the program draws the lines?

I think I explained it incorrectly posted by Kainien Morel on Nov 15 2011 1:06PM

Basically, my problem arises from the fact that I'm using a conic projection, and when I draw a line over the north pole it is over the "tip" of the "cone"--and warps it accordingly. Is there any way to draw a polyline that doesn't abide by this, and just behaves like the ruler tool or the preview line tool does?

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