Posts Tagged: Geo-tagging

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3
Jun 09

Geotagging III – how to associate names to the places you have been to

As promised, here is the continuation of the series on my geotagging workflow!

Now, after steps one and two, I had my photos on disk with the GPS latitude and longitude position (and altitude) embedded within the JPG files. Specialized applications like GeoSetter would allow to open a Google Maps window at the location where the photo was taken, or offer export capabilities into Google Earth to place the photos onto the virtual globe.

But, my image archive is organized using keywords, and I usually manually tag images (add keywords) with the names of the places I have been. For instance, with a single click I can extract all images I have made in the Berchtesgaden alps area from my archive. I certainly wouldn’t want to fly around on Google Earth and virtually travel to Berchtesgaden in order to find them – so what good do those latitude / longitude coordinates do?

So, for example, I’d like the computer to automatically tag and file the following image of one of my absolute favorite places in Italy with the keywords: Italy, Tuscany, Castelnuovo dell’Abbate, Sant’Antimo.

antimo

As often today, out there the web already has the solution: Services like GeoNames, which usually are for finding the geo coordinates for a street address (something every car navigation system excels at), also offer a service which technically is called a reverse lookup: You would use this service if you know the geo coordinates of a place, but want to know the name of it. Or even the street address. And this is exactly what the photographer needs, right?

If you visit their website at GeoNames.org, you will not find the reverse lookup easily (because this is not the use case they have built their web site for). But if you technically savvy reader browse to the Download / Webservice page, you will find the documentation for the reverse geocoding services. Now, for example, we could ask the friendly site for the name of a location I had on one of my images, namely 43,049N and 11,489E. This would be coded into an URL, and you can click on this to see the answer of geonames.org: http://ws.geonames.org/findNearbyPlaceName?lat=43.049&lng=11.489

Now, don’t get scared. What you are looking at is the computerized reply of geonames.org telling you that this is a place in Italy with the name of Montalcino, home of the wonderful Rossos and Brunello red wines (Ups, it forgot to mention that! But it would, fasten your seatbelts, if we had asked the right question). But web services are really for computers to talk to each other, and not us to try to do this for the 897 photos I brought from Tuscany.

The good news is: This is how it works, and Friedemann Schmidt, the author of the GeoSetter software, has already built this function into GeoSetter!

Here is how I got the names of the places as keywords into my photos’ metadata using GeoSetter:

  1. I opened the folder with the photos from step 2, and GeoSetter displayed for those that had successfully received geo-coordinates the latitude longitude pair in the thumbnails’ subtitle.
  2. So, bold as I was, I again selected all photos using CTRL-A and then called the Images… Edit Data… menu item (or pressed CTRL-E ).
  3. In the dialog box that popped up, GeoSetter effectively allowed to change all data points of the images. In the Location tab, it has a Get from Web and a Get All From Web button. The latter is only enabled when more than one photo is selected. Here is a screenshot of a successful run of Get From Web for a single photo:
  4. So I pressed Get All From Web… and the magic started.
  5. Theoretically, I would have been done here and could just press CTRL-S again to save the data GeoSetter added to the images. There were two complications, though:
    • GeoSetter lost connection to the GeoNames webservice once in a while, making the processing of such a large batch of photos a bit of a stretch. This problem can be mitigated by increasing the WebServices timeout in the File… Settings… menu item’s dialog window in the Internet tab, entry box labeled Timeout for Web Services. I increased that number to 50, which fixed the problem for me.
    • For some places, obviously GeoNames did not answer with a unique place name, but with multiple possibilities. Seems logical, as I could have been right between two cities, so how should it know? The one problem was that GeoSetter did offer the option to say Select for All, but this led to all images being assigned the one selection I had made. So if it is unsure whether an image should be attributed to Montalcino, I had to confirm it image by image, because if I pressed the Select for all button, it would take that answer also for the images where it was unsure if they were in Siena… This leads to quite some clicking when doing many images at once.
  6. Now, press CTRL-S to save your work, and exit GeoSetter.

BTW, the save operation of GeoSetter does keep your original JPG file in case it screws up. It is a good idea to try out these more bleeding edge workflows only on copies of your images, not your originals! I always photograph raws, and run the geocoding on the JPGs I am creating for the image archive, so I still have the raw file in case the JPG breaks.

Done. After that, I did import the images as usual into my Photoshop Elements 5 image archive, and the tricks and hoops to jump through for that to work smoothly shall be part of another story to be told another day – maybe your favorite image archive works just as we all would envision it to work.

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2
Jun 09

Geotagging II – Adding GPS location data to the photos

tuscany

Wow – May is over as is my vacation :-(

Tempus fugit.

But of course I used the vacation for quite some photography, and also continued my engagement with geotagging. On our one week trip to beautiful Tuscany I had made sure to carry my Garmin Venture HC with my nearly all the time, switched on and set to record my track.

Now I downloaded and cleaned up the track just as I outlined in my previous post on geotagging, and will explain how to get the GPS information into the EXIF data of the photos!

After some searching and trial of various software packages for this, most namely the freely available gpicsync and a trial version of the commercial RoboGeo, I have settled for the also freely available GeoSetter software.

When you start up GeoSetter, the default view shows you the image browser on the left hand side, and a map window on the right hand side. This is not the optimal setup for what we are trying to achieve, so I changed my view setup by turning off the Map (for now) using CTRL-M or the respective menu entry in the View… menu, and turn on the tracks window using CTRL-T or again the menu item for this.

Now you need to locate the two data items you want to merge: In my case, I did:

  1. Browse to the directory on my hard disk where all JPEG images from Tuscany reside using the Explorer-like address bar. If you do this correctly, the thumbnails of your to-be-geotagged photos will appear, and the preview window will show a bigger version of the first photo.
  2. Use the Tracks window to browse to and open the GPX file with the positional track information created in the previously outlined process. You can additionally use the little checkboxes in the tracks window to turn off older waypoints or anonymous track information that you do not want to be used for geotagging. In my case, there were older waypoints in the GPS device I had used to relocate my favorite restaurants from my prior visits to Tuscany :-)
    So here is a screenshot of GeoSetter after I opened the two data locations:

  3. Remember my comment on making sure to synchronize the clocks between the GPS and the camera? Finally, this time I had remembered to do this by taking a photo of my GPS device while it is showing a second-accurate current time. We’ll be using this photo shortly.
  4. Now I was ready to perform the real geotagging: Starting with one picture first for the cautious, or do a CTRL-A in the thumbnail view to select all photos, and press CTRL-G or call the respective menu item Images… Synchronize with GPS data file… to open up the synchronization dialog. This will take a while to show up if you do it like I did with 897 images in one run, but GeoSetter is showing a nice progress bar while it retrieves the EXIF information from all the selected images.
  5. Now, this dialog is quite a beast, but don’t worry, I’ll walk you through it. What I did:
    • Selected Synchronize with Visible Tracks as we had already located the positional data we will be using.
    • Let GeoSetter Interpolate Regarding Shoot Time With Last Or Next Position, as this can improve accuracy of Geo information when the track log was not that dense (contained many data points).
    • Allowed for a maximum time difference of, let’s say, 3600 seconds. If I stayed longer that that in one place, I might have left the GPS at home :-(
    • Used the Use Time Zone method, as I knew my camera’s time zone (no jetlag going from Germany to Italy – how convenient!), and this is the only method that will allow for the picture of the GPS device to be loaded
    • Disabled the Request Time Zone checkbox as I knew the time zone – I rather selected the correct one in the combo box available for this.
    • Checked the Add Time Zone over to Taken Date check box to have GeoSetter add the time zone information to the EXIF shooting data so the information is in there once and for all.
    • And used the Additional Time Adjustment Method as described in the following paragraph!
      So I clicked on the Adjust by Image Content… button and simply enter the time displayed on the GPS device in your photo of it into the edit fields – in my case, this led to a time correction of my camera’s time by -54 seconds. Not dramatic, but it helps to be precise once in a while.

      (Tip for this step: If you have selected the 897 images like I did and the photo of the GPS is neither the first nor the last image, better select only the image of the GPS device before pressing CTRL-G in step 4. This allows for doing this time calculation with the image, and later reuse the value found. GeoSetter makes it a bit hard to find the image of the GPS in the large image set selected).

  6. That’s it! Easy, wasn’t it? We’re ready to press Ok in the large dialog displayed. For verification, here is the dialog after I had it filled out:
  7. All images for which a corresponding data point in the track was found are now marked in red in the thumbnail view and a latitude / longitude position is displayed next to it. The red color by the way indicates unsaved changes, so after a verification that all is well we should save the result of our work (well ok, it was more the work of the software).
  8. For verification of an image’s position, use the map window (turn back on pressing CTRL-M) by selecting only the image you want to find on the map, and press CTRL-Z (or use the curious looking glass icon in the map view’s button row that shows only a single exclamation mark… I found using CTRL-Z works better for me):
  9. The final step – don’t forget to save the data! Just press CTRL-S!

By the way, for my 897 images I could automatically geo-locate only 782, and GeoSetter provided a nice warning about this. The setting of so many images at once took also a while on my old desktop machine, but if I don’t have to work myself, I’m fine with that.

But the advantages of really doing geotagging don’t stop with the display of the position where the photo was made on a map, so stay tuned…

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6
May 09

Geotagging – a renewed approach

Many times I have already made the attempt to utilize geo-tagging – the use of a GPS geo location device to “tag” or mark the location a photo had been taken. I have been a regular and enthusiastic user of Garmin GPS devices since the year 2000, when I bought my first $99 Garmin eTrex – the little yellow box that faithfully helped me to find the hiking track on some mountain meadow or my car’s parking spot in a large unknown city.

The basic idea for geo-tagging is actually simple: If you carry a (powered on) GPS device with you while you are taking photos, and that device has any kind of track logging mechanism, you can combine the information from the GPS tracker with the photo, use a location lookup service in the Internet to find out the street address for the longitude / latitude position the GPS recorded (now that sounds awfully simple, doesn’t it?), and tag your photos (read: add keywords) with the address information for easy searchability in your image archive.

The logical connection between a photo and the GPS track can either be made by the time stamp each photo and GPS track has – given that you somehow sync the clocks of the GPS and the camera – or by a cable connection between the GPS and the camera which allows the camera itself to write the position information into the photo right when it arrives on your memory card.

As I had always only planned to do some geo-tagging, I had carried the GPS tracking device with me while taking pictures, and dutifully saved the track path data on my hard disk. I had not really prepared the data for geo-tagging, nor had I connected the GPS device and the camera itself. So I had implicitly chosen the first approach: I have photos on my hard drive with the EXIF information when the photo had been taken, and I got GPX files for my location information for many days in the past 8 years – not all of them will have accompanying photos…

The challenge to clean this mess up will be documented in a series of posts where I will outline the software I use, and the solutions I find.

So to get back into geo-tagging and GPS-device-using mood I had recorded a track last Saturday on a bike tour that was really meant to explore the bike route from my home to the Ismaninger Speichersee birding area. I did not take my camera with me this time, but let’s see how far can we get in terms of visualizing the trip.

For read out of the track data from the GPS device to the desktop computer, I am since many years using the freeware program EasyGPS from Topografix. This nice tool has the advantage of fully supporting the GPX file format for GPS data, which is XML-based and can be read and written by many different GPS-related software packages, as we will see.

So when I fire up EasyGPS:

  • The only thing I do is to click on “Receive”, select the Tracks checkbox in the dialog box and click on OK. With the Garmin Venture HC I am now using and which sports a USB interface, the resulting download takes only a few seconds.
  • The resulting track data is stored on disk calling File… Save… from the menu, and selecting a directory where all my GPX GPS data files reside. I use an ISO timestamp time prefix in the form 20090506-explanationOfTrack.gpx filename to allow easy sorting of the directory.

The one challenge is that the EasyGPS will always download all data from the GPS device, so if you had not cleared out the device’s memory before recording a new track, you will end up with replicate data in the new file with the last one you downloaded. We will clean that up with the second software package:

For doing anything interesting with the track data (remember, no photos yet!) I use the also freely available tool GPS-Track-Analyse.NET from gps-freeware.de. Sorry, no international translations available as far as I can see, it seems to have a German website only. But Dietmar Domin, who has developed the tool and is maintaining this web page might be able to help you as he had requests and downloads from all over the world already!

So what I do in GPS-Track-Analyse after I opened the GPX file I just saved with EasyGPS:

  • Scan the list of tracks in the middle window to determine if there is old data from previous sessions in the file (because I forgot to clean the GPS device’s memory before starting the new trip), and whether the device somehow has broken up my trip into multiple pieces (which can happen when the device was turned off, or has lost satellite reception for too long).
  • The stale track data I just delete by clicking on the list item with the right mouse button, and select Track löschen to get rid of it.
  • The fragmented tracks can be reconnected by using the right-click menu item Verbinden, and selecting all fragments to be put into one track. I usually rely on the time information to determine if a track needs to be merged or not (I seldom have more than one track per day that should not be connected).
  • After this cleanup, I do revisit the smoothness of the height data recorded and might choose to smoothen this a little bit with the Trackpoints bearbeiten… Höhenprofil glätten… menu item. This is especially important for the tracks recorded with my old Garmin eTrex – the new chipset of the Garmin Venture HC (the “H” in the product name indicates it has this new chipset) is delivering much better data for this application in every respect. If you don’t have one of the H models yet, go out and get it now! You won’t believe the improvement in terms of accuracy and speed over the old models until you see it.
  • Save your work into a new GPX file. Remember, Al says <start of quote> save early, safe often. <end of quote>

The exciting part starts only now: Use the Export function to create a file with your track for Google Earth. I do select the KMZ Archive, use the speed for the color of the track and turn off the trackpoints. The application will open Google Earth with your track in all it’s beauty, and from there you can save it to a KML or KMZ file that you can share with others.

As an example, here is a map of my my 30 km bike tour from last Saturday, where we were touching (but not circling) the Ramsar area Ismaninger Speichersee.

The color shows my speed with green being slowest and red being fastest. I will spare you the legend and min/max values :-)

To be continued…

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