Re: Calculating intermediate latitude


"VB" <not@xxxxxxxxx> kirjoitti viestissä
news:1jl56gdwwjz2c.meycx1lxujr3$.dlg@xxxxxxxxxxxxx
> Hello,
>
> I have a raster map with a few points of known latitude and longitude.
> I calibrated this map in OziExplorer using two of these points, and
> after changing a few options I found out that map datum is WGS 84, and
> projection is Mercator. I believe these two are correct because now
> every other point on the map has proper lat/lon. As you see I'm not
> too advanced user...
>
> What I need is to calculate geographical coordinations for any other
> point on the map. I managed to calculate longitude using simple
> proportion, and the result is perfectly right. But I don't know how to
> calculate latitude, whatever I do I get wrong results. How can I do
> it? Moreover, I need formula, because I will need this to make
> calculations in Excel, so applications or web converters will be no
> use for me.
>
> All in all, for points A and B I have geographical coordinations and
> local pixel coordinations, and for point C I have local pixel
> coordinations and longitude. How to calculate latitude?
>
Check this. I have implemented Mercator projected coordinate conversion
based on this formula.

http://www.posc.org/Epicentre.2_2/DataModel/ExamplesofUsage/eu_cs34f.html

Eikka Uikkanen
http://www.kolumbus.fi/eino.uikkanen/gb/index.htm


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