[eluser]jedd[/eluser]
Hi Mr Yuttana and welcome to the CI forums. And don't worry - your English is much better than my Thai.
With EXIF - there's no native library for CI - but there
are some [url="http://uk2.php.net/exif"] EXIF functions within PHP[/url]. I've looked at these before, and found them to be pretty basic. I have often had to drop out, using PHP's system() call for example, to a command line exif tool.
The big problem with EXIF data is that it is not very consistent between different cameras - so your lat/long information may or may not be in the EXIF block, and may or may not be labelled in a way that you would expect.
I think your best option would be to develop a library or helper that can look at the EXIF information of each Image file that you upload, and record the data from that file and copy it into your database.
You would then search through the database later - this will be the fastest way.
It does mean that you will need to clean your EXIF data as you read it - but you can continue to improve your library to cater for different camera types (etc). You may find, via google, that other people have already done this kind of work, too.