Geotagging digital Photos- an Overview

[CapnJack]

Introduction
Geo tagging (or geo-referencing) is adding location information to pictures. If the tagging is with a GPS, it is easy to see where the photograph was taken allowing easier identification of the photograph later. This is helpful in guided tours, where the pace may be a bit fast to take notes about photographs. Also, you may not know exactly where you are in an unfamiliar city. Geotagging is also useful for nature shots since you know where a particular animal was seen at least once. With Flickr, Picasa, and other sites with maps, it is also fun to see where photographs were taken. Geotagging also provides a frame of reference for the pictures.

Geotagging is usually associated with a latitude/longitude that is read off of a GPS. However, an address or intersection in a city also marks the location where a photograph was taken. A cross bearing off of two landmarks from a compass also identifies a photographer’s location.

How to determine the picture’s location?
Manual
Tagging pictures manually was the only way to do it back in the film days. The photographer would note a location on paper after taking a photograph. The note may have been “roll 2, photo #3, New York, NY, 30th & Broadway”. In an area with many landmarks this is very accurate but, in wilderness areas, the location will be vague. This method is very inexpensive and requires no additional equipment beyond pencil and paper.

On board GPS
This is an option with many cell phone cameras since the GPS is built into the phone. For example, enabling location services in an iPhone (1) will add location information to pictures.

Nikon has a GPS device that works with their cameras that stores the latitude/longitude in the EXIF data in the photograph. Some cameras also have the GPS built in (CoolPix P6000 and Ricoh 500SE, for example) that will also store the image location.

Separate GPS
This solution is likely to be used by most people until GPS receivers are standard items in cameras. A GPS (or GPS logger, or cell phone with GPS capability) is left on and creates a trail. The trail contains the time a location point is logged, and the latitude/longitude. Before use, camera clock is synchronized to the time on the GPS device. After the photographs are saved on a computer, software is used that reads the time stamp on the photograph; the software finds the point on the data track with the nearest time (usually to within a second or two), and assigns the track location at that time to the photograph.

One can also just write down the latitude/longitude when they take a photograph, but this gets tedious. Using a GPS track is useful when several cameras are used- the same track file can be used for all of them.

Ok- I have the Location- how do I put it in the picture?
PC
I like to use Microsoft Pro Photo Tools, available as a free download (see ref 2). This tool uses Bing maps ( www.bing.com/maps ) to display location information. One can select a picture (or many of them) and pick the location the pictures were shot from the map. This information is saved to the EXIF data in the picture. You can enter an address or a cross street (such ad 30th and Broadway, NY) and the map will display that location. This makes the program useful without a GPS.

A GPS track file saved as GPX file format (GPS XML) can also be used with Microsoft Pro Photo Tools. Choose the track file, select the pictures, and the program will use the track point with the time closest to the time the picture was taken to determine the position. My experience with the program suggests it will try to interpolate the position for a picture if the track file is broken- this can put a picture in a different location than where it was taken, but this can be fixed by dragging the picture location to the correct location on the map. If the camera clock was not synchronized to the GPS, the program allows a time offset to be entered by sliders. I use a Garmin GPS; the MapSource program from Garmin creates the GPX track file that Photo tools uses. Other GPS receivers will use their own software to create the GPX track file.

Other metadata can be added, such as copyright, people in the picture, description, credit, event, and other data for organizing photographs better.

Macintosh
As Macintosh computers become more popular, geotagging applications are becoming more available. Some of them are listed here:
http://trick77.com/2008/07/19/review...mparison-mac/; as of this writing, all of the links work in this web list.

In general, the programs work in a similar fashion as the Microsoft software described above.

Web Based
Picasa uses Google Earth as a map reference. You choose the location of an image off Google Earth and Picasa will write the data to the picture’s EXIF metadata.

Flickr will read location information from a picture’s EXIF header and place the photo on a map upon upload. Conversely, the picture can be placed on a map using Flickr. Flickr uses data from NAVTEQ.

My geotagged photos are found here: Flickr: Explore JackSilver's photos on the map

(1) How to Geotag Photos on your iPhone | eHow.com, 6 Feb 2009
(2) http://www.microsoft.com/prophoto/downloads/tools.aspx , 7 Feb 2009

[bdbolin]

Nice article, thanks!

[inkista]

If your GPS device doesn't "speak" GPX, I recommend some form of GPSBabel front-end to convert dang near any form of track file to GPX.

On the OSX side, the freeware I've been using for about five years is GPSPhotoLinker.

[CapnJack]

Originally Posted by bdbolin

Nice article, thanks!

Thanks!

Originally Posted by inkista

If your GPS device doesn't "speak" GPX, I recommend some form of GPSBabel front-end to convert dang near any form of track file to GPX.

On the OSX side, the freeware I've been using for about five years is GPSPhotoLinker.

GPSbabel is good...I confess that I forgot about it. It's been around for a long time.

For more info on GPX, look here:
GPX: the GPS Exchange Format

Topografix seems to be the keeper of this format.

[voltech]

thanks i had been using atp photo finder its been working great too

[FuriousE]

Nice article, thank you!! Do you know of an iPhone app that can be used for this?

[CapnJack]

Originally Posted by FuriousE

Nice article, thank you!! Do you know of an iPhone app that can be used for this?

FuriousE, I'll refer you to the information below from one of the Mods as I don't own an IPhone...and I won't take credit for someone elses' work...

Originally Posted by Nicole

I use my iPhone for geotagging. The one question I have for you is how you want to work your geotagging workflow. I just use either Trails or GeoCorderFree and then I email myself the gpx file and use a LR plugin. It works, and generally works well, but I often forget to turn it on and then I'll also forget to import the gpx file as well. That being said I also haven't been on many photo walks lately, so when I have used it in the past it's worked well. I've found that GeoCorder works better in the city than Trails for some reason, but Trails is great if you're taking outdoor hikes and stuff because it also keeps track of your elevation and stuff and has some really nice detailed reports essentially.

My boyfriend uses Geotag (I think) and we've had the hardest time getting it to work and actually associate with the photos. I'm not sure if it's something we're missing out on or just not catching on to, but yeah.

So, geotagging on the iPhone of photos from another camera works well as long as you don't mind adding steps when you get back to your computer. Hope that helps a bit

Once you have the GPX file, you're set. I've read that photos taken with an iPhone have the lat/long saved in their EXIF file, you just need to let Flickr read this data.

[Galarina]

Originally Posted by FuriousE

Nice article, thank you!! Do you know of an iPhone app that can be used for this?

Take a look at my GeoLogTag iPhone app. It tracks your location while you're shooting photos and assists in the geotagging process afterwards.
You can try out the free version that's functionally identical to the full version except for the fact that the free version automatically deletes logged locations after 2 hours.

App Store
Website