The title sounds like a daunting little geekfest, doesn't it? Not at all – even Audrey has managed to figure it out.
Once you begin logging location data with your Sony GPS-CS1 (Sony GPS-CS1KA) GPS device, you'll need to import data from the device, convert it into something usable, and finally embed it into the EXIF data of the photograph. Although this may sound complicated, it’s not. It just takes some patience the first few times around, after which it becomes second nature. We’ll explain it all in this portion of our case study.
If you are new to geotagging, we suggest you read Part 1 of this series first.
A note on naming conventions: We actually use an earlier model of Sony’s GPS device, the Sony GPS-CS1. To remain current, we will refer to the device as Sony GPS-CS1KA, the updated (yet functionally and technically similar) model.
Disclaimer: We should point out that Dan currently uses a PC laptop and Audrey a Mac PowerBook. The importing steps are achieved with a PC while all other steps (conversion and embedding in photos) are performed on a Mac. For each step outlined in this case study, we will identify alternative software to use for PC or Mac.
Our unusual hybrid PC/Mac approach to geotagging is due to the division of duties on this trip (i.e., Audrey chose the responsibility of geotagging photos) and the software available to us.
Structure of Log Files on the Sony GPS-CS1KA
Note: The Sony GPS-CS1KA, and the GPS Image Tracker that comes bundled with it are only compatible with PCs running Microsoft Windows and Intel-based Macs running Mac OS X 10.4.9. The following website had been keeping up with the Mac-compatibility with the Sony GPS-CS1KA.
Once you’ve been out and about and have logged some GPS location coordinates with the Sony GPS-CS1KA, attach it to your PC with a USB cable. The GPS will appear as a “Removable Disk”, much like a USB memory stick might. If you double-click the drive letter corresponding to your device, the following is displayed:
Inside the GPS directory, you’ll find each of the individual GPS logs generated by the Sony GPS-CS1KA. The device generates one log for each set of continuous signals. If the device is turned off and then back on, a new file will be created. Not that we’ve found it necessary, but the GPS Image Tracker does allow multiple files to be merged. Open the file in a simple text editor like Notepad and you’ll see all of the raw GPS data logged by the device. A detailed description of what each of the individual GPS records means is fortunately beyond the scope of this case study and not necessary to actually use the data.
Importing GPS Data from the Sony GPS-CS1KA
- Open you’ve installed it on your computer, open the GPS Image Tracker software bundled with the Sony GPS-CS1KA.
- Click “Import Log Files” to import the GPS log files from the device to your computer.
- The system will prompt you to set the time zone for the log files you are about to import. For those of you using the GPS Image Tracker software to match logs with photos, this is critical since the logs will be matched to photographs based on time stamps. For those of you using other software to batch match photos with GPS logs, if you make an error, you can correct it later. Setting the time zone in the GPS Image Tracker will not alter the original GPS log file.
The GPS Image Tracker software stores GPS log files in the path: Documents and Settings-user-Application DataSony CorporationSony Picture UtilityGPSUtilLog
Once the log file import is complete, a dialogue box appears.
If you are running Microsoft Windows, you can use GPS Image Tracker to geotag your photos directly by clicking the “Add Picture Files” button. The newer model of Sony’s GPS device, Sony GPS-CS1KA, comes with a software bundle called Picture Motion Browser.
At this point of our process, Audrey takes the .log files (text files with GPS data) from Dan (using a USB memory stick) and takes the following steps on her Mac Powerbook to complete the process.
Converting GPS .log Files to .gpx Format
- Software: GPS Babel+ freeware
- Objective: Convert .log files to .gpx file format
- Operating Systems Supported: PC, Linux, Mac OS
- Set the following variables:
- Operating Mode = Waypoints
- Input File Type = NMEA 0183 sentences
- Output File Type = GPS XML
- Under “Input Options”, use the “Select” button to choose the file ending with the .log extension that you’d like to convert.
- Press “Save File” in the bottom right-hand corner and choose the name and location of the file. We organize and name files by date in order to keep things organized. The resulting converted file will have a .gpx extension. The original .log file will be unaltered (i.e., you’ll have two files, the original .log file and the converted .gpx file).
Matching Location Data with Photos
- Software: GPS Photo Linker, freeware
- Objective: match data in GPS .gpx data files with photos, based on time stamps
- Operating systems supported: Mac OS
- PC alternative: A PC version of Picture Sync is rumored to be in Alpha. Another PC alternative is GPicSync.
Matching location data and photos is accomplished in two ways 1) automated tagging based on user-set tolerance rules and 2) manually tagging for any photos that remain untagged after this automated process (unless you change tolerance values and re-run the automated geotagging process).
Automated Geotagging Steps
- Click “Load Tracks” and choose the .gpx files you want to use for geotagging (whose time stamps are close to the photos you'd like to match).
- Click “Load Photos” and choose the photos you want to tag.
Note: If you have a large batch of photos to tag, we recommend that you choose the photos, grab a glass of wine and return 5-10 minutes later.
- Choose “Batch” and set the tolerance for the geotagging, either by distance or time. We always choose time, and set it to 600 “seconds from closest point” so that if the software cannot find GPS log data based on the exact time a photo was taken, it will search progressively (in either direction, before or after the photo was taken) to find the closest point. In this case, if the software cannot find a matching GPS log within 600 seconds (10 minutes), then the photo will remain untagged.
- Press “Batch save to photos” and the software will begin to embed the selected GPS log data into the EXIF data of each photo for which it has found a match (based on time stamp). If you are processing a large batch of photos, we recommend that you grab your second beverage since this step may also take time.
Note: Click “Time Zone” to make sure that the time zone is the same as the time the photos were taken (i.e., the same time your camera was set to). If in your batch of photos, you have photos taken in multiple time zones, we recommend that you split the photos into multiple batches by time zone.When the batch geotagging process concludes, an alert will appear in the bottom left-hand corner of the screen indicating how many photos were successfully tagged and how many remain untagged.
Bonus: If you happen to be connected to the internet while GPS Photo Linker is batch matching photos, the software will consult an online database to find the name of the town, region, and country associated with the latitude and longitude data. If it finds a match for the GPS coordinates, it will additionally embed this text location data into the photo’s EXIF data. Though embedding this data may be useful, it adds additional time to the process.
If all of your photos emerge from this process with geotags, then you are done and your photos now have geolocation data embedded in their EXIF data.If some of your photos remain untagged, then you have some manual tagging ahead of you (unless you choose to change GPS Photo Linker's tolerance values and re-run the automated geotaggging process):
- Select “Manual” and you will see a list of your selected location logs in the bottom left hand side.
- To find photos without geotags, you’ll must manually search through the photo thumbnails to find ones whose Latitude and Longitude tags are blank.
- Find the geotagged image that is closest in time or location to the non-geotagged image. Go through the log files for the day the closest geotagged photo was taken and find the exact log data by way of the time of the geotagged photo.
- Then select the photo (or photos) that need geotagging and save the Latitude and Longitude data from the log to the photo/photos by pressing “Save to photo.”
Congratulations! All your photos now have the location data embedded in the EXIF data, so the process is now finished! Read Part 3 to find out what you can do with the photos now that they are geotagged.