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Mapublisher natural earth reprojection question

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#1
koen onestopmap

koen onestopmap

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Hello,

 

this could be a stupid question but I'm struggling quite a while with this one. Also, I can't find much info on the internet.

 

Is it possible to import the natural earth data centered on another area than europe? My problem is that when I make a map from an area that's at the border off the natural earth WGS84 data, I don't know how to cut it prior to reproject the whole thing.

 

You could say, don't cut it, but sometimes the projection I need does not work with the whole earth: orthographic for instance, because lines that are on the back of the globe are visible and thus are messing up my map. Btw, if someone would know how to get rid of those, I would be very happy to know also :-)

 

I'm afraid this could be a "beginner"-question, sorry about that.

 

thanks,

Koen.

 


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#2
Hans van der Maarel

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You can set up a custom copy of any projection you want and specify your own central meridian. MAPublisher will then center it on that meridian. However, for line and area features it's best to cut the data on "the other side" of the globe (i.e. whatever central meridian you picked, minus 180 degrees) to make sure you avoid those lines you want to get rid of. I use FME to make that cut, but you can also use MAPublihser. So let's say I want to center it on North America (-100 degrees)

  • Import the data in the standard WGS84 projection.
  • Create 2 layers, let's call them crop1 and crop2, and put them in the Map View as area layers.
  • Use the Area Plotter to create a rectangle from (-180,-90) to (80,90) on layer crop1.
  • Use the Area Plotter to create a rectangle from (80,-90) to (180,90) on layer crop2.
  • Duplicate any layers you want in your map. The copied layers will have "copy" added to their name. MAPublisher will automatically add the copied layers to the Map View.
  • Add detail to the 2 crop rectangles, you can either use Object -> Path -> Add Anchor Points or the MAPublisher path tools "add detail" option.
  • Use the Crop to Shape option with the rectangle on layer crop1 to crop all the original layers (make sure to lock the other layers and tell MAPublisher to skip locked layers)
  • Use the Crop to Shape option with the rectangle on layer crop2 to crop all the copied layers (again make sure to lock the other layers and tell MAPublisher to skip locked layers)
  • Reproject the Map View, select the projection of your choice and make a copy of it. Edit the copy to have a new central meridian, in this case -100.

 

There will probably still be some artifacts that you need to clean up, especially area features on the spots where the 180 degree line is on land (Fiji, Siberia and Wrangel Island) but this way you can minimize those. Ocean features would be more of a hassle but you can fake that by just using a blue background layer. When you're done you can merge the layers back to the original set.

 

Hope this helps.


Hans van der Maarel - Cartotalk Editor
Red Geographics
Email: hans@redgeographics.com / Twitter: @redgeographics

#3
koen onestopmap

koen onestopmap

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Wow, thank you Hans, quite an impressive answer  :)

I'm getting into it as soon as possible.

Also learning a lot from your video tutorials on Mapublisher.


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