[OpenLayers-Users] What is the relationship between zoom level and longitude/latitude

[Adrian Popa]

Hello everybody.

I'm trying to zoom to view an area for which I have the minimum and 
maximum longitude/latitude. Basically I would like to zoom in to see a 
rectangle with known coordinates. I already calculated the center of 
this rectangle - so that's not a problem - the map centers beautifully 
to that.

The problem is: I have to find out which minimum zoom setting would 
allow my area to be fully visible - so I need to choose a zoom setting. 
There must be a relationship between the difference in longitude (or 
latitude) to a zoom level.

I wonder if anyone knows this relationship - or should I determine it 
empirically.

Thank you.

By the way, my map is using spherical mercator projection, but my 
coordinates are in longitude/latitude (although there is no problem in 
converting them...).

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Adrian Popa
NOC Division
Network Engineer
Divizia Centrul National de Operare Retea
Departament Transport IP & Metro
Compartiment IP Core & Backbone
Phone: +40 21 400 3099