Geotagging on the Mac

2009-03-09T12:26:00.000-07:00

One of the big new features of iPhoto announced in iLife 09 is support for geotagging. During the keynote and in the demonstration video posted on the website, Apple use a Nikon P6000 which rather handily has a GPS built in. But what about the rest of us users who have cameras without GPS or those that would like to geotag their photos but don't want to use iPhoto?

Well we have a couple of options. First (and easiest) is to manually enter the location. Nice and simple. However, I'm not a fan of this method. First, of all it only works well if you have a reasonable idea of your location. Secondly, if you take half as many shots as I do on holiday, then the prospect of spending a few hours tagging each image doesn't really appeal.

The second option is to use a GPS device and then sync the records it produces with your photos. The theory is simple when activated, the logger will make a record of my GPS co-ordinates every few seconds. This then builds up into a very accurate trail of your movements. The simplest analogy would be the breadcrumbs from Hansel and Gretel.

I personally use a GPS logger from Holux, snappily titled the M-241. It's a small film canister sized unit and is very simple to use. When switched on, it will automatically begin logging until you instruct it to stop. No fussy set-up, no sorting files - turn it on and it is ready to go. When ready, simply upload the track using Bluetooth. Unfortunately, this model is not officially supported on the Mac. This tends to be the case with 99% of the GPS loggers that I looked at. Luckily some enterprising people wrote a piece of software called BT747 which allows the unit to be used with the Mac. It's not the best looking bit of software, but it is functional.

Once we have our tracks uploaded to the computer, the next step is to get the co-ordiates into your photos. Thankfully the situation here is rather healthier as there are some very good pieces of software for the Mac to perform this exact task. The way it works is that the software looks at the timestamp on the GPS co-ordinate, and the timestamp of the photo you have taken. When it finds a match, it writes the co-ordinate into the photos metadata and voila one geotagged photo.

But enough about the theory, lets see how it works in practice.

The first and most important step is to ensure that the internal clock on your camera is in sync with the clock on your GPS unit.

If these times differ, then your photos are going to be tagged with incorrect location data.

Once your logger has a fix on the satellites and is starting to record its log, then you're good to go!

The next stage is the fun part - go out and take your photos.

Once back at your computer, launch BT747 and click 'Get Log' to download the track you have have just made to your computer. When downloaded, you can export this into other formats such as a KML to view the trail in Google Earth. For this example we will convert our file to GPX.

At this stage I would recommend copying your images off of your memory card and into a directory on your computer. Although this next stage can be done directly on the memory card, its better to be safe and not modify your original files.

The program that I recommend to sync your GPX file with your photos is name HoudahGeo - we'll launch this now.

HoudaGeo requests its data in stages. First we'll add our image files.

As we can see, there is no positioning information at this time. Now we open the GPX file we created with BT747.

Immediately, HoudaGeo has compared the timestamps and matched the co-oridinates to the photos. We can now save the information, and the files are available to use.

Now what?

So now we have our geotagged images, what can we do with them? Well in iPhoto, they have a new feature called 'Places'. It's something that I'm looking forward to playing with, but what can we do without iPhoto?

I store all my images in Lightroom - Adobes excellent organisation and cataloging program. If we take a look at the metadata in Lightroom, we can now see the GPS co-ordinates, and by clicking on the arrow next to it, we can see where the photo was taken using Google Maps.

As you may know, I put a few of my photos on Flickr. Flickr has had support for geotagging for quite some time. When a geotagged image is uploaded, Flickr identifies this and automatically places it on a pop up map linked from the photos page.

Flickr also has maps in which shows all your geotagged images on a much larger map. You can also perform image searches from this map and see other users geotagged images.

Here we can see I've geotagged images in England, Scotlad, Turkey and of course Guernsey.

Another Mac application is Ovolab Geophoto. This places your images on a Google Earth style globe. You can zoom in for more detail, and it will also show a marker in Google Earth. In the example below, you can see the photos taken around Holloyrood Park when for Steve and Gina's wedding. Thats one of the nice things about geotagging, you can see exactly where you were at the time of the photo.

One other thing that I like to do with the GPX file is to import it into a program called RubiTrack. It actually has nothing to do with photography, and is designed as a fitness monitor. I use it as a catalogue for my trails. It has a nice mapping feature, and records such details as the weather conditions when then trail was made. it can also read some of the more advanced data such as speed and altitude.

It makes for a nice reminder of the places you've been - for example this trail of a boat trip I took in Turkey last year.

If you have any suggestions for Mac GPS applications, I'd love to hear about them.

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Geotagging on the Mac