My Geotagging Workflow

Posted by jeremy on October 13th, 2008 filed in Howto, Mac, Photography, Photos, Technology

Earlier this year, I blogged about my experiences with the Sony GPS-CS1 GPS datalogger. It was not the device I had hoped for, so I decided to try the Amod AGL3080.

The Amod has been a good choice. It works well with my Mac, has good battery life, and is decently accurate. When the device is connected to the computer via a USB cable, it shows up as a removable drive. To retrieve the GPS logs, simply copy them from the removable drive. This is ideal, because no special drivers are needed to use the device. The logs are written as a plain text file, in a format recognized as “Sony LOG”.

The Amod captures a data point every second and writes the data to a file. When the device is power cycled, it starts a new file. I use this to my advantage by starting a new file when I change the CF card in my camera. That way I know that each GPS log file corresponds to the shots on a card. One thing to be aware of is that the Amod device can take several minutes to acquire a signal, especially if it is in an area with a lot of tall buildings. It’s not a bad idea to power it up and wait for the indicator light to start flashing, indicating that it has acquired a signal, before starting to shoot.

Once I have finished a shoot, I tag all the shots prior to processing. Tagging the RAW files first ensures that the geotag metadata will follow the files around no matter what I do with them later. So before importing the photos to Aperture, I do the following:

1. Connect the Amod via USB and copy the logs to a GPS folder on my Desktop
2. Delete the logs from the Amod unit, and eject the device
3. Copy the photos from my CF cards to folders on my Desktop, divided so that each folder is a batch of photos that has a single GPS log file associated with it
4. Convert each GPS log to GPX format using HoudaGPS. Here are the settings to convert from the logs the AGL3080 creates to GPX format:


HoudaGPS Ready To Convert

5. Tag each batch of photos using GPSPhotoLinker:


Batch Tagging with GPSPhotoLinker

Now all the photos have the geographic data associated with them. I can import them into Aperture, process them, export them, and upload them. The geotags stay with the photos just like any other EXIF data, and I don’t have to worry about doing anything else.

If you’re looking for a way to capture GPS data to tag your photos, the Amod AGL3080 is tough to beat.