GeoTagging, sometimes referred to as Geocoding, is the process of adding geographical identification meta data to various media such as websites or images. The data usually consists of latitude and longitude coordinates, though it can also include altitude and place names.
This involves using a GPS to log a track of your walk and then using this information to tag the photographs with the position where it was taken. Sounds complicated? Not really, all that is done is that the date/time the photograph was taken is compared to the date/time of the way points in the GPS track, once a match is found the way point lat/long values are written to the EXIF header of the JPG file.
Try this other web site of mine http://www.flickr.com/photos/tferenc, simply geotagging the photograph and up loading it to the web site shows the photograph on a map.
Alternatively the JPG filename can be renamed to include the date and location it was taken e.g.'IMG_1337 2006-12-02 SK 11980 60980.JPG', just outside Hartington, Derbyshire. It is then obvious where and when it was taken, or use XnView to put the file name onto the photograph.
The assumption is made that you do not have any software to do this. The links to the software can be found on this page.
The GPS stores the date/time values
using GMT so I have set my camera to GMT as well. The main problem when
GeoTagging is figuring out what the time offset is between the GPS and
the photograph. To find out exactly at what time the photo was taken
use exiv2. But once this has been done it is always the same, unless
the camera adjusts the time automatically when the clocks change!
photographs can be placed on line for everyone to view using Flickr or
a web site like ours to display the track and the photographs, but we
would strongly suggest using NDWGeoTag, at least, to rename the
JPG files so that the date and location are part of the name. Therefore
everyone will know exactly where and when the photograph was taken.
What is the accuracy? We would say the error is less than 5m. from our
tests using a 1:25000 map.
All the software/web sites mentioned here are either free ware or the web sites mentioned have a free option, some of the software was written by us. All that has to be purchased is a data cable for the GPS to link it to the PC. Mine was bought via Ebay it cost about £8 inc. p&p, just make sure the cable is correct, i.e. Serial or USB. Or of course you could make your own.
This software is for Windows, but we have found the odd bit of Mac software, see below. Also we have written some
Linux scripts to do this as well.
To get started, only G7ToWin and NDWGeotag are required, both free ware.
Program Description G7ToWin our current favourite WWMX Location Stamper A Microsoft research tool that GeoTag the JPG files using the GPX file. NDWGeoTag Our own program to parse the GPX file to add OSGB data to the photographs,
There is no installation program, just unzip all the files into a directory of your choice.
exiv2 This is used by NDWGeotag and is included in the zip file. It is a DOS/Console application that displays all the Exif data in the JPG file. The -pt option is the one to use. Renamer Renames files. Very handy to change the IMG portion of the name or if the files have been renamed incorrectly, during testing always use a copy of the photographs. Syz
Make your own data cables. XnView A superb program for viewing and converting bitmaps,can be used to batch convert a group of files, to do things like writing the file name onto the photograph.
Program Description MAC Geotagger 1.2 Mac GeoTagger
Acronym Description EXIF Exchangeable Image File Format GMT Greenwich Mean Time GPS Global Positioning System GPX GPS Exchange Format JPG Graphics file type/extension (lossy compressed 24bit color image storage format developed by the Joint Photographic Experts Group) Lat Latitude Lon Longitude OSGB Ordnance Survey Great Britain Serial Serial (RS232) Communications port SUB Universal Serial BUS
Ignore these unless you want to write your own software or you want some really technical information or software.