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Creating maps when crossing the dateline

abmayfield

I have a very unusual issue that is surely NOT to be very widely applicable: I am working with samples obtained very close to the international dateline (Fiji). When I go to overlay the data onto a map using pre-created shape files (one feature I love about JMP, BTW), it basically plots them on opposite sides of the globe, rather than center them around the 180 degree dateline. Upon a quick Googling, I noticed that this is an issue in other graphing software. I tried changing the access to geodesic, but this did not help. I tried to make a plot and place a background map of FIji behind it to see if this would do the trick, but it basically would not load the map! Any thoughts?

Accepted answers

Craige_Hales

Add 360 to the negative longitude.

formula to add 360the image maps wrap but the outlines do not.

outline does not wrap

All comments

Craige_Hales

Add 360 to the negative longitude.

formula to add 360the image maps wrap but the outlines do not.

outline does not wrap

abmayfield

Great! This seems to do the trick. I'll just need to manually change the y-axis (i.e., longitude) when I go to make the actual figure (i.e., convert 181 degrees back to -179). Thanks.

Jeff_Perkinson

Actually, I'm curious about the problem that you're seeing as it works for me if I've got the Geodesic axis scale on both X and Y.

Try the attached data table and the script in it and see what you get.

Here's my result.

Parallels DesktopScreenSnapz059.png

LatLon.jmp

abmayfield

Jeff,

Your data table plots correctly, but for some reason mine does not. Maybe I input something wrong? If you plot latitude versus longitude using in this table, they are plotted on opposite sides of the globe, even when set to geodesic!

Fiji GPS coordinates.jmp

abmayfield

If I set both to axes geodesic, I get the attached image. I also tried geodesic US, but the outcome was the same. In any event, it's not hard to add 360 to the negative values, so I think I can just do that.

Screen Shot 2018-07-13 at 17.12.41.png