Geotag your photos

[stubbsy]

First a quick definition: Geotagging your photos means you are adding GPS info such as latitude and longitude to the EXIF data in your images. This in turn means that you can physically tag their shooting location on a map of the world. To see this in action go to my SmugMug Geotagged photos section and click the Map This! button at the top. You should see a Google map of NZ with pins in it marking where each photo was taken.

Now we have that out of the way I want to make a second important point - you can geotag your photos even if your camera doesn't support GPS tagging (typically only high end cameras support GPS tagging when you take the shot) and this mini review describes how to do that AFTER the image has been uploaded to your computer.

Here is what you need (apart from a camera and a computer of course):

1. A GPS unit of some kind. While not essential (you can manually locate the GPS coordinates on a google map), a hardware GPS unit will remember where you've been and save the locations for you. The GPS unit must have the ability to save track logs in one of a number of standard formats. The bulk of units do. Additionally there must be some way to get these track logs onto your PC from the unit be it a serial or a USB connection
2. Geotagging software

A suitable GPS unit costs from around US$95 with freight and the RoboGeo software I''d recommend you use (Windows only) costs US$40. At the current exchange rate with the US that's maybe $160 Australian for the hardware and software or $45 Australian if you already have a suitable GPS unit.


1. GPS Units
There are three basic categories of GPS units readily available - in car navigation units, off road tracking units and GPS data loggers. Of these it's rare to have an in car unit that also allows the saving of tracklogs to your PC, si I'll only talk about off road units and data loggers.

Off Road GPS trackers
In essence an offroad tracking unit (eg the popular Magellan and Garmin brands) have a screen and and some built in or loadable maps. The GPS inside the unit tracks where you are going and displays that via the on screen map as a nice squiggly line. As the price increases so to do the features, but even very basic units will meet your geotagging needs since most support transfer of track logs to your PC. If you have such a unit for off road use or for geocaching then you're half way to the complete photo geotagging solution. One small drawback of such units is the size of the saved tracklog is more restricted than is the case for GPS data loggers (eg a base unit may support 10 tracks of 2,000 data points). Good places to look for these units in Australia are Johnny Appleseed and GPSOz

GPS Data loggers
A GPS data logger is a screenless GPS unit with built in data storage and PC connectivity. The GPS inside the unit tracks where you are going and saves the locations internally. You then later connect the unit to your PC and upload the GPS track log. Some also have bluetooth connectivity (so you could,for example, use them with GPS software on a PDA for in car GPS navigation). While they can store much more track log data than an off road GPS unit (upwards of 60,000 data points) that's pretty much all they do. Many come with software for image tagging, but most software supports jpg files only. A good place to look for data logger units is Semsons in the US - I've bought from them and found their service fast and their prices attractive. Freight is around US$28

2. Geotagging software
If you buy a data logger then it may come with Geotagging software for free, but generally the best you can do is tag jpg images. There may be a more advanced software upgrade that also supports raw files (eg Gisteq PhotoTrackr has a Pro software upgrade for US$20), but my experience is that the software can be disappointing. In fact my original choice was a more expensive data logger with software that supported raw files, but I've since ditched that in favour of better software.

Regardless of the software used your images are geotagged by comparing the file date and time of the image to the GPS tracklog to see where you were physically at that time and hence where the photo was taken.

I'd recommend you use the RoboGeo software (US$40) which supports a multitude of GPS log types including those from Garmin and Magellan as well as standard formats such as NMEA and GPX. RoboGeo also supports writing to most raw image formats and safely makes a copy of your raw file before it adds GPS info to the EXIF header. Essentially you do the following with RoboGeo:
- load your track log
- load your photos and identify their GPS location using the tracklog
- tell RoboGeo to write the GPS data from the tracklog to the image EXIF header

My ultimate decision when I investigated this was to get the Gisteq PhotoTrackr Pro principally because it's software seemed like it would be all I needed (total cost US$115 + freight). I soon found the software buggy and limited and bought RoboGeo. Knowing what I do now I'd have bought the RoboGeo software and a cheaper unit such as the AMOD AGL3080 (total cost US$65 + freight). The Amod has the added bonus of not needing proprietary software to upload your track logs - it just shows as a usb drive on your desktop and you drag the files across.

And that's pretty much it. If you have any questions, or some of this isn't clear feel free to ask.

[SNW]

I've been geotagging all my photographs were possible for a while, using a Garmin C60Sx and exporting the track logs for Downloader Pro to parse when downloading images of my CF cards. The GPS information is added to the XML sidecar. Great for documenting where native orchids and things were found for future reference.

One question I do have though is: Adobe Bridge CS3 supports GPS EXIF and displays this information in the metadata panel, however when converting RAW images to TIFF then JPG the GPS information is lost. Is this simply because Photoshop CS3 doesn't understand the GPS metadata tags even through Bridge does?

[stubbsy]

Adobe Bridge CS3 supports GPS EXIF and displays this information in the metadata panel, however when converting RAW images to TIFF then JPG the GPS information is lost. Is this simply because Photoshop CS3 doesn't understand the GPS metadata tags even through Bridge does?

Photoshop should be preserving your GPS EXIF details UNLESS you're using it's Save for Web feature which strips out all EXIF (and so should be avoided). I just opened one of my tagged NEFs, saved it from PSCS2 as a jpg and it still has GPS in the EXIF. I then saved it as a TIFF and the GPS info is gone so it may be the TIFF save that's the problem. Why are you saving to TIFF first? Why not just save staright to JPG from your post processed raw file.

[SNW]

Photoshop should be preserving your GPS EXIF details UNLESS you're using it's Save for Web feature which strips out all EXIF (and so should be avoided). I just opened one of my tagged NEFs, saved it from PSCS2 as a jpg and it still has GPS in the EXIF. I then saved it as a TIFF and the GPS info is gone so it may be the TIFF save that's the problem. Why are you saving to TIFF first? Why not just save staright to JPG from your post processed raw file.

So that's where it's getting lost! thanks for investigating this.

My general workflow is:

RAW -> Camera RAW -> TIFF (16-bit) -> PS (selective enhancement and sharpening, optionally resize to web) -> JPG (not using "Save for Web", but a manual transform to sRGB, Mode to 8-bits, then Save As).

Surely the lack of GPS data in EXIF for TIFF files is an oversight? GPS is in the Exif standard, nothing else is lost.

[SNW]

Experimenting a little more I've found a workaround.. instead of exporting from Camera RAW to 16-bit TIFF, exporting to Photoshop .PSD (16-bit) maintains the GPS data.

[radar]

Peter,

thanks for the great review. I've been looking at doing the GPS tagging. I'll be getting GPS for bushwalking so a tracklog will be available. I will also be doing the tagging once I get back to the computer, from the tracklog. There are some great open-source tools that do it as well. I'll dig up the info and add it to this thread.

thanks,

André

[cyanide]

stubbsy, thank you for raising this. I hadn't ever seriously thought about geotagging until now, but that was a very interesting post, and it's great to know that it is possible even without a camera that supports geotagging.

Food for thought.

[radar]

Peter,

I looked back in my notes and by using two free tools, you can get all the GPS tagging done. Your only requirement is that you have a GPS that can record a tracklog. By using exiftool and gpsPhoto.pl, you can use your tracklog to geotag your photos. From the gpsPhoto web site:

The purpose of this tool is to allow a hiker to record a GPS tracklog or waypoints and later (at home) synchronize this GPS data with the timestamps of the image exif data of his digital camera, in order to locate and store the position where the picture was taken. The tool writes coordinates, altitude and additional metadata to the Exif and IPTC metadata section of jpeg, nef and potentially other file formats. Optionally, a Google Earth kml file is created containing the gps tracklog and the image positions.

The web site for gpsPhoto is:
http://www.carto.net/projects/photoTools/gpsPhoto/

The website for exiftool is:
http://www.sno.phy.queensu.ca/~phil/exiftool/

These tools will do jpg, nef, cr2 and crw. It is pretty easy to setup on Linux and Mac OSX. It is all done from the command line so one has to be comfortable with using the command line.

I'll be getting a GPS for bushwalking, so I'll be using these tools soon. I'll update this post with my experiences.

Cheers,

André

[photohiker]

As soon as you start looking at this stuff, it's everywhere!

I visited the ExifTool site mentioned above by radar (thanks André!) and was surprised to see GPS Tagging is already included in a tool I use - Image Ingestor. (info page) That's pretty handy, will have to give that a try.

Now if zenfolio will just get the code written to support geotags...

Michael

[radar]

For the Mac OS X users out there. I had the chance to be in a workshop yesterday with Bruce Dale. It was a panorama workshop.

One of the applications that he showed was gpsphotolinker. It is extremely easy to use. It will get the tracklog directly from your GPS, you point it to a folder of photos and there you go, you get your gps co-ordinates added to your photos. It has a nice little feature of "Show on map..." which launches Google map and takes you to the co-ordinates of the photo.

Cheers,

André

[SNW]

For the Mac OS X users out there. I had the chance to be in a workshop yesterday with Bruce Dale. It was a panorama workshop.

One of the applications that he showed was gpsphotolinker.

Thanks for sharing this app. I had a quick play around with it last night, very easy to use, nice UI. The only thing I don't like about it is that it doesn't support writing the GPS EXIF to XMP sidecar, I really don't want anything rewriting or touching my masters. This would be a fairly simple feature to add, XMP being just XML anyway so I've left some feedback with the developer.

[ATJ]

Peter,

Can you see any reason this unit wouldn't work?

http://www.bhphotovideo.com/c/product/559314-REG/Holux_M241_M_241_GPS_Datalogger_with.html

[ATJ]

While looking around for information on Geotagging and that Holux device, I stumbled on this: http://code.google.com/p/geotag-lightroom-plugin/

[stubbsy]

Peter,

Can you see any reason this unit wouldn't work?

http://www.bhphotovideo.com/c/product/559314-REG/Holux_M241_M_241_GPS_Datalogger_with.html

I can't see why not Andrew. The price is reasonable, but I'd also suggest you look at the range at Semsons

That Lightroom app you link looks interesting too.

[ATJ]

During my investigations into GPS loggers and geotagging in general, I have come up with a novel use for geotagging.

For a number of years I have been synchronising my camera with my dive watch(es) so I can determine the depth at which a photograph was taken. Both watches record the depth of a dive at 5 second intervals. I have been using a semi-automated method to determine the depth of each photograph (if interested, see: Determining the depth of my dive photographs. It is a semi-manual process and I have been trying to work out ways to automate it. The biggest problem I had was working out where in the EXIF or other metadata to stick the depth.

Back to geotagging. Many GPS loggers also record the altitude along with the longitude and latitude and the altitude tag seems to be supported through most of the geotagging software as well as EXIF and image software. Well, depth is just negative altitude and so becomes the perfect place to store depth data.

GPS doesn't work under water, so I would never be able to accurately record the location a photograph was taken, but I have already been logging the longitude and latitude of my dive sites (usually the entry point) which is going to be close enough. It was quite easy for me to write some code in my custom Lotus Notes dive logging application to write a CSV file with the date, time, longitude, latitude and depth (as a negative number). I can the use GPSBabel to convert the file to GPX format. I then use GeoSetter to syncronise the photographs with the GPX file and it embeds the longitude, latitude and altitude in my photographs.

I have even got it working so that when used with Lightroom I don't have to modify the NEF files (although the JPEG files are modfied). In Lightroom, I select the files I want to synchronise and "Save Metadata to Files". This updates the JPEG files and writes .XMP files for the NEF files. I then fire up GeoSetter, select the same files and "Synchronize with GPS Data Files...", selecting the directory where the GPX file was stored. I save the files which creates new JPEG and XMP files (making backup copies of the old ones). Back to Lightroom and "Read Metadata From Files" and the data is there.

One problem is that Lightroom and a few other applications don't know how to read negative altitude data and so they ignore the fact that it is negative. Maybe one day they'll fix that. The only other problem is the backup copies of the old files which I don't really need, but I can easily clean them up.

[ATJ]

The only other problem is the backup copies of the old files which I don't really need, but I can easily clean them up.

OK. I have solved this one. GeoSetter lets me overwrite the files and I'm happy for it to do that for the JPG and XMP files (which I can always recreate).

I have found another bug in Lightroom, though. It won't read some metadata from JPG file. In fact, I can import a JPG, update some metadata (contact, copyright, image location, etc.), "Save Metadata to File" and then immediately "Read Metadata from File" and the added data is gone - although it is visible in the JPG file.