# Mapping

I want to write a GIS application where I have to find a location corresponding a given latitude and longitude.
I have placed the map in a picture box. I know the latitude and longitude of the top/left and bottom/right corner of the map.
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Commented:
Hi
First of all it depends on latitude range. On Mercator projection latitude scale isn't proportional. If range isn't large (up to 4 degrees), you may consider it is, so the easiest way is to set:

Picture1.ScaleMode = 0 'User
Picture1.ScaleLeft = LeftValue
Picture1.ScaleTop = TopValue
Picture1.ScaleWidth = RightValue - LeftValue
Picture1.ScaleHeight = BottomValue - TopValue

Now all your map is scaled according your coordinates and all mouse events (move, click, down/up) will return scaled values.
But if you need large range (more then 5 degrees) or very precissious coordinates, you have to use Mercator's projection formulaes.

Cheers
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Commented:
And you know the width and the height of the picture box?  Umm.. why not do some quick math on the numbers

I don't know what the lattitude and longitude numbers are, but if you can give me an example I can show you the math.

basically width / (lower right longitude - upper left longitude)

width = 800
ul long = 100
lr long = 105

800/(105-100) = 160  so, you have 1 additional point of longitude for every 160 horizontal pixles

the same math would work for lattitude.

does that help?
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Commented:
Hi Gopakumar,
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Commented:
per recommendation

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