Geotagging South Bay aerial photographs


There have been a few threads over the last couple of years about using GPS loggers to tag photographs with location data. The general notion has appeal for it would be nice to provide specific locations for my work in the South San Francisco Bay salt ponds. To date I have geotagged almost a thousand images on Flickr by manually dragging the images to their location on the Flickr/Yahoo map. While this is easy enough the coordinates thus assigned seem to be specific to the Flickr system and Yahoo’s somewhat less than impressive mapping application. So I have been looking for a combination of hardware and workflow that would be easy to use on my Mac and would geotag the source image in addition to its Flickr version.

Flickr map of Benton images

Map of my geotagged images on Flickr – I find the interface confusing.

Read on to see a neat airborne GPS solution.

Geotagging with the iPhone

In November I tested several programs for using my iPhone 3Gs as a GPS logger. EveryTrail (free) proved pretty easy to use and allowed the retrieval of a GPX file after uploading a trip log to their WWW site. I ended up using HoudahGeo (paid) to synchronize data in the GPX file with the EXIF data of photographs from the session. HoudahGeo has an intuitive interface, can process RAW files, plays nice with Lightroom, and can export to Google Earth.  In addition to filling an image’s GPS Latitude, GPS Longitude and GPS Altitude fields with location data from the GPX file, HoudahGeo will also reverse geocode images by assigning City, State, and Country values to their respective EXIF fields based on latitude and longitude.

In the November tests I was able to geotag all 800 or so images from a trip to Salt Pond E6B with a minimum of fuss (samples here). My workflow to prepare images for Flickr generally involves selecting a set of RAW files in Lightroom and exporting these as jpg files with a maximum dimension of 1200 pixels. These files are then uploaded to Flickr. The location data added to the RAW file by HoudahGeo makes the transition to Flickr just fine and the image is automatically assigned a map position once uploaded.

While geotagging with the iPhone was fun enough there were a few shortcomings. For instance, the EveryTrail software had to run continuously during a photo session so I could not use the iPhone for other purposes. And the positions recorded by the iPhone were those of the kiteflyer rather than the camera cradle. This led me back to KAP Discussion page to look for posts regarding GPS loggers that might fly with the camera.

An airborne GPS logger

In a discussion thread earlier this year Nick_K described the QSTARZ BT-Q1300S GPS Travel Recorder, which is the size of a key fob and weighs a mere 22 grams. Among the GPS loggers available these days the BT-Q1300S is quite compact and the device can deliver a GPX file via USB or Bluetooth connections. I ordered one up and in short order my dSLR camera cradle was GPS enabled.

QStarZ-1300s GPS logger

The QStarZ-1300s GPS logger mounted on the side of my camera cradle.

The maiden flight for this setup was last week at Salt Pond A23 and everything worked quite well. I have posted a set of geotagged images on Flickr. I was able to import the flight track into Google Earth for visualization with and without geotagged images. The camera cradle’s flight path is interesting and matches well my memory of the session. While there is general agreement that consumer GPS loggers are relatively inaccurate in fixing altitude data, points within the  flight track seem to have reasonable relationships to each other while the whole set seems to be too low by 10 meters or so.

Google Earth visualizations of the camera cradle’s flight track:

Google Earth display of camera track

Google Earth display of camera track

Google Earth display of camera track

Wish list

A while back I made a page that took each of the images in my Salt Pond Colors and Textures poster and linked it to a corresponding view in Google Earth. It would be nice at some point to log direction, tilt, and accurate altitude along with GPS coordinates. One could then imagine software creating the equivalent Google Earth placemark.

3 Responses to “Geotagging South Bay aerial photographs”

  1. ykcid00 Says:

    Nice work and effort

  2. blalor Says:

    Nice work, Cris! If you’re interested, I have a mostly-automatic workflow for geotagging images. I’ve got a handful of Python scripts: the first one imports NMEA or GPX tracklogs from the device (either an Amod AGL3080 or Garmin Oregon 400t) and indexes them by time in an sqlite database; the second one processes a batch of images from the camera and embeds the GPS data into the EXIF tags. From there, I use Automator to suck them into Aperture on my Mac, but you could do something similar for Lightroom. The point is that the whole process is completely automated and the data is stored in the photo, so it never gets lost. It works with both JPEG and RAW files that are supported by Phil Harvey’s ExifTool. I’m happy to share if that interests you. I hear good things about HoudaGeo, but I need the process to be as automatic as possible.

  3. Remonty ?ód? Says:

    Wow! Those are some nice photos, I especially like the Airbone gps logger photos 😉