This is going to be a rather lengthy post again but bear with me. It will also be a bit technical so I will have to explain some of the basic technical points before we start on the really nifty things here. But in the end you will learn how to use your GPS receiver to track your movments when shooting outdoor, you will learn how to download this information and use it to geocode your pictures so that when they are uploaded on sites such as Flickr your photographs will automatically appear on the map in the correct location.
The resons for geotagging
It is a way of organising your photographs that is pretty new actually. Never before has it been so easy to know where a certain photograph was taken and it is a great way of finding other people’s photographs from a certain location.
It also means that if you use your GPSr when you are on holiday you know exactly on which spot you were when you took that picture and it is a great way of sharing information about good photographic spots, not to mention that it sort of becomes a photographic diary, tracking your movements around with your camera and GPSr.
There many be also personal reasons for geotagging, for me it started because I am a map freak. I love maps in all sorts of ways and I spend half a fortune on them. These days I mostly use electronic maps because they are more versatile but when I go hiking I always have a paper map as a backup – you never know when electronic will fail you.
There are two kinds of photographers, those who has experienced equipment failure and those who will.
This is very true.
These are the steps
There are a number of steps involved, many of these you probably already do in your post processing but there are some new one here that I will go through later on. But this should give you a general overview on how geotaging works.
- Synchronize the time of your camera with the time in the GPS receiver.
- Make sure you are logging your movements to a track-log in the GPS receiver.
- Photograph away, move, shoot some more…
- Save the tracklog in the GPS.
- Transfer the tracklog to your computer.
- If not already in GPX format convert to GPX format using GPSBabel software.
- Transfer the photographs to your computer.
- Convert your pictures to JPG if necessary (if you shoot in RAW)
- Use GPSPicSync from Google to syncronise time and write lat/long info to your pictures.
- Upload the finished pictures to the web service of your choice.
Choice of GPS receiver (GPSr)
There are today many brands available but two of them stands out in terms of quality and popularity and they are Magellan and Garmin. Magellan has a whole range of suiteable outdoor GPSr that fits most budgets, they are called the ”eXplorist” series. Garmin has similarly ranges of outdoor GPS receivers. If you are looking for a GPS receiver they are all quite similar, some comes with mapping software, others have Geocaching functionality built-in which is nice but none of this is required for this purpose.
What is required is that the GPS receiver can save a track log that can later be downloaded into your computer for post-processing. The various makers of GPS receivers have different internal formats but most can save in a format called GPX which is an interchangeable format used to make it possible to transfer data from one brand GPSr to another.
I am personally using a Magellan eXplorist XL and it is a great outdoor GPSr. Not only has it got the biggest screen on any GPSr but it has accessories to attach it to a bike, car windscreen, it runs a full day on its batteries and when attached to a computer it behaves like any other Mass Storage Device making it easy to extract the TrackLog files after being out with it.
Which receiver you chose is irrelevant really but talk to the sales people and explain that you want to eventually convert track logs to GPX format and you should not go wrong.
Setting up GPSr and Camera
Once you got the GPSr of choice familiarise yourself with the manual. Make sure you understand how to start a tracklog going, how to save it once finished and start a new one. Check that you may actually transfer it to your computer. If the GPSr software that comes with it does not allow you to save/convert to GPX format directly then check out this software which speaks most GPSr dialects and should help you convert from your native format to GPX.
The next step is to set up the camera. The only thing you need to do is sychronize your camera time setting with the GPSr time, this can be done manually, it’s not a problem if you are a few seconds off, but you should not be off with more than a minute if you are walking around taking pictures, or more than 10 seconds if you are biking or driving around to take pictures.
Take your GPSr outdoors and let it find satellites and get a fix on your location. All receivers are capable of displaying satellite time, so switch to the screen where you can see the satellite time. Next turn on your camera and find in the menu where you can set time and date. Set the date to match the GPSr reported date. Set the time to match the GPS displayed time.
Now you are set to go.
Take pictures, move, take more pictures…
Start the GPSr tracklog feature if needed, most start logging immediately when they have a fix on the satellites. Now you my put your GPSr away if you wish and concentrate on moving around taking pictures with you camera. Each picture you take will then have a time stamp. And in the position tracklog of the GPSr there will also be time stamps and positions. This means that later we may match the time stamps in your pictures with the time stamps in the GPSr log and figure out your exact location when you pressed that shutter release button.
Move to a new location take pictures. If you go indoor you can even turn off your GPS, once you are outdoor again you may turn it on. Allow it to find satellites and get a fix on your position before you start snapping away if you want more exactness.
When you are finished on your photo excursion go to the menu in the GPSr and save your tracklog. I generally save it with a name that indicated the date and a running number. So my first log today when I am writing this would be called 080721-1.LOG and the next one today would be 080721-2.LOG and so on. (I live by the date format of YYMMDD but you can use whatever makes sense to you). It is however wise to name the logs in a way that they sort on name by date taken it makes it easier in post-processing to find which log was correct for each picture.
Get the data from the camera and GPSr
First of all download the pictures from your camera. If you are shooting in JPEG format then you are set to go immediately. If you are shooting in RAW format you need first post-process your photos into JPEG and make sure that the EXIF-information stays intact because here is where the time and date of your pictures when they were taken are located.
The next step is to transfer the track-log from your GPSr device. Consult your manual on how to do it, some require special softwares, others can just be attached by USB cable and you can copy the files as if they were from an external harddisk (USB Mass Storage Device). Whatever way you do it you should end up with a tracklog file somewhere on your PC.
Now it is simplest to keep the tracklog file and the photos in the same location, I generally put them in a folder with a name that tells me what I was doing, shooting or the date. Then put the tracklog and JPEG pictures in this location. If you were not already getting the tracklog file in GPX format then now is the time to use the GPSBabel tool and convert it into GPX format.
Once converted you need another tool which is the whole secret to the automatisation of coding the geolocation on your pictures.
This is a great software that you can download here. GPicSync is a Google Software and you may use it under their licence free of charge.
Once installed and started you should see a screen like this:
Click on the ”Pictures folder” and browse to where you saved your pictures.
Click on the ”GPS file” and browse to the location of your GPX file.
It is optional if you wish to create a Google earth file, if you have this software this is a great way of checking that it went alright.
You may also export to a Google Maps export, this means it will generate files that you can put on a web server to show your entire journey through Google Maps for anyone in the world. Really cool stuff!
Select ”Create a log file” and ”Dates must match”. Select ”interpolation” if parts of your journey was faster than walking or jogging speed. Backup pictures creates backups before GPicSync tries to change your JPEG files. You should already have backed up your files now!
UTC Offset: This is important. In Sweden this is +1 in the winter time and +2 in the summer time. If you are not sure you may have to test with different values and see if it matches the location you think you were in!
”Geocode picture only if time different … is below” this means that any pictures in the folder that is not within this interval will not be geocoded (have their location information written to them). You can try it out with various settings here since it will tell you if some pictures are not coded properly. In your first run you may want to keep this at something like 3000 seconds. If you do that then you will see lots of pictures missed out if you get your UTC offset wrong!
Once done press the button ”Synchronise!” and watch the log. You should see message appearing that it is writing geocode information latitude and longitude to your pictures in the folder. Once it is done you may press ”View in Google Earth” if you have this software installed. Then GE will be launched and your track and pictures can be investigated here. When you are happy with your result press Quite or Quite and Save (so your settings will be the same next time you start).
Check it out in Google Earth
If you have not installed Google Earth already, then by all means go and do so now. This software is great for exploring the world. It is also a great way of checking that your UTC offset in the previous step is set properly. When GPicSync is finished you will have a Google Earth doc file to click on. If GE is installed then it will open the file and display your photographs.
If you find that your time offset is not right, that your photos are one our early or late or more, then correct the UTC offset in the GPicSync program, run again and then check again in GE. Sometimes this is a little counter-intuitive but it is usually a good way of checking before uploading the pictures.
Uploading your pictures
The last step is to upload your pictures to an online repository where they automatically add your pictures to a geolocation database. Several such places exists, I use Flickr so I will describe how this works. The procedure is similar on most of these services.
Before you do anything, the first time, you must check if your Flickr account is set up to accept geographical information on your pictures when uploaded.
This can be done from your Flickr Account page that you can access after you are logged on. From the Flickr meny chose ”You -> Your Account”. Click on the tab called ”Privacy & Permissions” and then check what comes up. You are looking for one settings here that you may need to change:
Defaults for New Uploads: Import EXIF location data -> Set to ”YES”
That should be all that is necessary. After this you may use your normal Flickr Tool to upload the pictures from the folder where they were geotagged. Once done you should be able to find the photos on Flickr and now the option ”map” should be enabled on the right hand side on the photo page.
Click that link and your photo should display on Flickr’s map.
You have now successfully uploaded geotagged photographs to Flickr!
Some terms and definitions
I have collected some of the new terms and definitions here to make it easier to look them up. Let me know if something is unclear, leave a comment on the article and I will try to expand.
- Global Positioning System – a system of satellites in orbit above the earth that are regularly transmitting signals to the surface of the earth. These signals can be received with a GPSr (GPS Receiver) which can then use these signals to calculate the exact location on earth.
- This is the GPS receiver unit. There are mainly two types of consumer GPSr that you can buy in any electronic store these days. The first one is the autorouting receiver used to navigate to street addresses when you drive a car or similar. This GPS unit may not have the tracking function required for this article. The second type is the outdoor sports GPS receiver unit that we will be assuming you have. This is also known as a ”hunter’s GPS” or ”Trekking GPS”.
- A track log is a file written by a GPS logger. It generally contains information about the time, longitude, latitude and altitude that the GPS receiver logged at the given time. With this file it is possible to construct how the GPSr moved over time.
- A software from Google that will check the date and time on a photograph in JPEG format, match it against a position in a GPS track-log and then write the latitude and longitude coordinates back into the photograph allowing geo-aware sites take advantage of this information.