clipped from: rakaz.nl When you geotag a photograph you are basically adding a very specific combination of a latitude and a longitude coordinate to the image file. Every point on earth can be represented by a combination of these two coordinates.
The notation that we are going to use today is by using a single fractional decimal number for each coordinate. This notation is used by most modern computer applications and web services, such as Yahoo Maps, Live Maps, Google Maps and Google Earth.
Picasa stores the coordinates inside a special area inside the image file called Exif, designed to store meta information about the images. It is usually used to store the camera model, the settings of the camera and the date when the picture was taken. Exif is a common standard and also allows us to include geotagging information. Extracting this information with PHP is quite easy because PHP provides us with an easy to use module for reading Exif data.
The easiest way to use the geotagged information on your website is by creating a link to one of the mapping services such as Google Maps, Yahoo Maps or Live Maps from Microsoft. The only thing you have to do is create a simple link with a couple of parameters that control the location, the level of detail and the type of map. Below you will find examples of the most common mapping services.
Alternatively you could also use the Google Maps API (example, source) or the Yahoo Maps API (example, source) to embed a map of the location directly in your own webpage. Instead of linking to Google or Yahoo, your visitors are able to view the location of a photograph without even leaving your own website. All you need to do is sign up for use of one of their APIs and follow their examples and use our coordinates. Both APIs are very extensive and we are only scratching the surface of what is possible, but that is far beyond this article.