An Introduction To Geo-Photography
So youve returned from a wonderful holiday. You had a great time, and have lots of photos to remind you. Chances are that you used a digital camera and took twenty times the number of photos that you would have taken with a film camera.
Digital photographs offer many advantages over film. They can be reviewed on the spot to ensure that what you saw is what you got. They can be edited. Botched photos can be discarded without wasting film and the cost of developing. No longer do you have to wait a week for the photos to return from the developer.
There is one important thing, however, that digital photos will not allow you to do, and that is to write on the back of the photo to record the date, the place, and the subject.
Wouldnt it be good if we could do something similar with our digital photos?
Even better, what if the camera did this for us automatically? Well, to a large degree it can. Not only can the time the photograph was taken be recorded, but also the exact location. Such information is recorded within the image file as Exif (EXchangeable Image File Format) data.
Most digital image files store information about the photograph itself (called metadata). To be useful this information needs to be readable and ideally needs to be in a standard form. Most camera manufacturers use the Exif data standard, which allows metadata to be encoded in JPEG and TIFF files. Exif metadata may include:
- Date and time.
- Camera information (aperture, ISO, shutter speed, focal length, metering mode).
- A thumbnail image.
- GPS (Global Positioning System) data including latitude, longitude and altitude.
- Image descriptions and copyright information.
- Makernotes (this is used by manufacturers to encode extra information).
Viewing this information is surprisingly easy. In Windows, one needs to select the photo in Windows Explorer or in Windows Picture and Fax Viewer. Right-clicking the mouse brings up a menu from which the user can select Properties, then Summary, then Advanced. A significant amount of information about the photo can often be found, however this method does not display GPS data.
There are dedicated, stand-alone Exif viewers such as Opanda IExif, and add-ons for Mozilla Firefox and Internet Explorer, which display Exif data on right-clicking the image. Two of these are Exif Viewer and Kuso Exif Viewer.
Location, Location, Location
So how does one get the location (GPS) data into the digital image file? There are four general solutions:
1. Use A Camera With An Inbuilt GPS
While there were some early models that did this, and some current high-end models used for surveying, there are surprisingly few cameras with this functionality today.
There are some recent mobile phone/camera combinations, such as the HP hw6915 sport GPS, and there are also some car navigation systems that include a camera that will add the GPS coordinates, including Navman AIOs (N40i, N60i). However, these systems do not take the high-resolution photos to which most digital photographers are now accustomed.
2. Connect A GPS Unit To The Camera
Some cameras allow data from a GPS unit to embed location data into the image file at the time the photo is taken. Such models include Ricohs Caplio 500SE (which embeds data wirelessly from a nearby Bluetooth GPS unit) and the Nikon D300 (via an adaptor cord purchased optionally). Wireless Bluetooth solutions are obviously preferred as a cabled arrangement adds bulkiness to the camera.
3. Add The Location Information Manually
Some software products, such as RoboGeo, allow you to do this, either by typing in the GPS co-ordinates or by clicking on a location on a map. While this may be viable when working with one or two photos, it becomes tedious to calculate positions for multiple photographs.
4. Syncronise Your Camera And GPS On Your Computer
This solution is often the most practical, and the authors preferred GPS photography method.
Under this arrangement, the photographer uses a GPS device to record his/her movements whilst shooting the photos. Operating independently from the camera, the GPS unit simply logs the latitude and longitude at regular intervals (e.g. every 15 seconds), and the exact time of each log entry. This tracklog, is later transferred to the photographers computer.
Because the photographers camera will have recorded (into the Exif data of each image) the time that the photo was taken, it is easy for computer software to look at this time recorded (in the tracklog) and match it with the corresponding latitude and longitude. This location information is then added to Exif metadata for that image.
Because the timestamps are the only information used to perform the match between the image and the GPS data, this approach requires that the cameras internal clock be accurately matched to the GPS units own clock before GPS photography commences.
Where to start?
If you have a GPS unit that can record tracklogs, and if this can be connected to your computer, then you already have most of what you need. On your next excursion try the following:
- Turn the GPS unit on and allow it to get a satellite fix.
- Set the camera time to exactly match the GPS time.
- Set the GPS to record a tracklog based on 15 second intervals.
- Carry your GPS unit with you whilst taking your photos.
- When you have finished taking your photos, save the tracklog on the GPS.
- Load the photos to your computer, and import the tracklog from the GPS.
- Use a program such as RoboGeo to add the GPS data to the photos (geo-tag).
An alternative is the free program Grazer. It could not be simpler, and works well, but is light on extra features. One downside of the program is that it does not give error messages when something goes wrong.
And now the easy solution
Using a GPS unit is OK for those who have one and have taken the time to learn to fully use it. For most of us however, a simpler solution is needed. This is where GPS data loggers come in.
Data loggers are units dedicated to recording GPS tracklogs. They are typically small and will usually function longer than most GPS units on a single charge/set of batteries. The process simplifies to:
- Synchronize the times for the GPS data logger and the camera.
- Turn on the data logger and take it with you when photographing.
- Upload your photos to your computer.
- Plug in the data logger and run its software.
Examples of GPS data loggers include Sonys CS1, GisTeQ, iBlue 757 Pro 32, GlobalSat DG100, TraCKsTICK II, WinTec WTC-200 and ITrekZ1.
And now the fun
There are several fun, interesting, and useful things you can do once the Exif data is imported:
Locate Where The Photo Was Taken
Using Exif Viewer in the Firefox web browser, one can pin-point the location for any geo-tagged photo on a Google Earth map (right-click, select View image Exif data, scroll to GPS Info and select Google Maps). Other software can also be used such as Picture Motion Browser or PhotoTrackr.
View A Map Of Where You Went
The path that you and your data logger followed can be plotted on a map. The location of each photo can also be highlighted and linked back to the image, adding context to the photo.
Stamp Your Photos With Exif Data
The location and time a photo was taken can be stamped onto the visible image using RoboGeo.
View A Slideshow Of Your Trip
Programs like PhotoTrackr can play a slideshow of your images while displaying a map showing where each photo was taken.
Upload Your Photos To The Internet
PhotoTrackr directly enables uploads to Google Earth and locr. Once done, others can view the photos based on geographic location. Photos can also be uploaded to Flickr in order to share your photos with the world.
Improvements in photo quality and falling costs have caused the uptake of digital cameras to surge in recent years. The increased popularity of these devices has resulted in an explosion in the number of complementary products and services designed to extend their usefulness GPS related solutions being one of the more interesting categories.
Combining GPS devices and related software with digital cameras adds another dimension to modern-day photography. The technology is readily accessible, adds value to your photographs, and most importantly, is enjoyable to use.
Posted in Australian eHealth