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#1
Hans van der Maarel

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Hi everybody,

 

I need some help identifying this map projection.

 

Attached File  4A_vraag.jpg   213.28KB   35 downloads

 

It's not centered on Greenwich, for starters. I'm guessing it's using Florence meridian (11.25 degrees east). Winkel Tripel kinda looks like it but when I overlay that it appears I need more stretch in the N-S direction (or less E-W).

 

Any suggestions?


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#2
Strebe

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I can't look into this rigorously until I get home from work, but it's likely Winkel tripel. Be aware there are two primary usages reflecting different parameterizations, and if this one is not the more usual format as adopted by NGS, then it is likely Bartholomew's usage.

--daan Strebe

#3
souvik.gis

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Is it Winkel tripel projection system? Please have a look....



#4
Hans van der Maarel

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According to my client, who has a copy of the original atlas, a bit of text in the index refers to the Winkel Tripel projection. I've created a graticule that matches the one on the map, limiting it to the "whole" cells (so from -120,-80 to 160,80) and overlayed that in MAPublisher, this is what it looks like.

 

Attached File  Screen shot 2013-10-22 at 15.29.48.png   1.18MB   14 downloads

 

So it's pretty spot on along the equator but gets progressively worse towards the poles.

 

Played around with the latitude of origin and after some trial and error I arrived at 42, which seemed quite appropriate :rolleyes:

 

Attached File  Screen shot 2013-10-22 at 15.36.19.png   1.19MB   18 downloads

 

Not quite there yet as you can see, but considering I have no idea when, how and to which standards the original map was produced I'm calling this "close enough" for now.

 

Thanks for your suggestions Daan and Souvik!


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#5
Strebe

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Bartholomew's usage is 40 degrees for the equirectangular component. That's probably the intent here, but definitely use what works!

--daan Strebe




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