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Mercator projection defined by two standard...   Pete Whitworth Dec 02, 2002
Re: Mercator projection defined by two stan...   Melita Kennedy Dec 02, 2002
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Subject Mercator projection defined by two standard parallels 
Author Pete Whitworth 
Date Dec 02, 2002 
Message Hydrographic charts are often drawn on a Mercator Projection with a defined standard parallel which is not the equator. If I set the ArcMap display to World Mercator (which assumes equator as standard parallel)and then modify the standard parallel to a different latitude the display remains the same. Is there any way of getting ArcMap to recognise a Mercator Projection with two standard parallels ? 
   
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Subject Re: Mercator projection defined by two standard parallels 
Author Melita Kennedy 
Date Dec 02, 2002 
Message When you set the standard parallel, you are setting both standard
parallels. That is, if you set the standard parallel 1 to 40N,
implicitly, the other standard parallel is 40S. The display won't look
different, but if you check a point off the equator, you 'll see the
coordinate values change pretty dramatically. Here's an example.
The point is on an island off the southern tip of South America.

World_Mercator
-7199962.76 -7308888.34

World_Mercator with 40N
-5523135.13 -5606701.72

Melita 
  Melita Kennedy
ESRI Product Specialist