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Geo-tagging is the writing of geographical information in image files. Downloader Pro can automatically geo-tag JPEG and raw files by storing positional information in the form of latitude and longitude read from track log data from a GPS device. This information is written to the standard EXIF GPS shooting data stored in JPEG files and in the XMP sidecar file for raw files and can be read by image browsers such as BreezeBrowser Pro.
Many handheld GPS devices can store a track log which can be downloaded to a PC. The track log contains both positional data in the form of latitude and longitude and the time in UTC (aka GMT). Downloader Pro is able to read the track log data and the time each picture was taken and use this to calculate where the picture was taken. It is important that the camera's clock is set accurately in order for this to work.
Some GPS devices such as the Sony GPS-CS1 GPS Tracker are designed specifically for photography and are very convenient to use with Downloader Pro. The Sony device is simply turned on before you start taking pictures and automatically logs your position every 15 seconds. When you download your photos you connect the GPS Tracker to your computer using a USB cable and Downloader Pro will automatically read the track logs and store the latitude and longitude in your files as they are downloaded. It can also optionally create a track log file which can be viewed in Google Earth or Google Maps.
With other GPS devices it may be necessary to download the track logs to your PC before downloading your images. Many GPS devices simply appear as a removable drive when connected to a PC using a USB cable and can be accessed directly by using the "Search removable drives option". Please consult the manual for your GPS device for information on how to download the track log to your PC.
Downloader Pro is able to read track log files in NMEA format with a .log or .nmea file extension or GPX files with a .gpx or .xml file extension. The free GPSBabel utility can be used to convert between many different GPS formats if your GPS isn't able to store track log data in NMEA or GPX format.
Select "GPS settings..." from the Edit menu in Downloader Pro to enable and setup GPS geo-tagging.
When "Lookup place names using www.geonames.org is selected Downloader Pro will connect to the internet to lookup the place name and other information using the latitude and longitude for the image. You also need to provide your Geonames username when using the Geonames service. You can create an account by visiting the Geonames website: www.geonames.org
This information is stored in the tokens shown in the example below and can be used to automatically add place name data to the IPTC/XMP data.
If Downloader Pro is unable to obtain place name information the tokens above will be replaced with empty values.
It is important that Downloader Pro is told what time the camera's clock is set to so that it can use the timestamps of the images to read the location data from the GPS track log. Normally both the camera and the computer are both set to local time and you only need to select "Camera is set to local time". If your camera is set to a different time zone from local time "Camera is set to local time" should be unchecked and the time zone offset wrt to GMT should be entered e.g. New York in the summer time (during DST) is four hours behind GMT and so a value of -4 for should be entered for the offset from GMT.
If your camera clock is out by a few minutes you can compensate for this by entering a value in the "Camera clock error" field.
If you are unsure that the time settings have been set correctly you can check them by comparing the "Camera time" display with the current time displayed in the setup menus on your camera.
The "GPS fix window" setting specifies how close the time of a GPS fix in the track log needs to be to the time the picture was taken for it to be accepted. Setting a large value will increase the chances that a GPS fix will be found in the track log but it may not be very accurate if the GPS track log has gaps in its data e.g. if you turn the GPS on, take some pictures in one location for a while then turn the GPS off, drive to a new location and forget to turn the GPS on again before taking more pictures DLPro will record the first location for the second set of pictures if the "GPS fix window" is set to a large value. If the "GPS fix window" is set to a small value (smaller than the time to drive from the first location to the second location) it won't find a suitable GPS fix in the track log.
Please note: Setting a large value for the "GPS fix window" only affects the accuracy of the GPS data stored in the image if there are gaps in the GPS track log. If the GPS track log contains a fix within a few seconds of when the picture was taken an accurate position will be stored in the shooting data of the image even if the "GPS fix window" is set to a large value.
Track Log Settings
Downloader Pro also needs to know where to find the GPS track log files and this is specified in the "Track log settings" section.
Some GPS devices such as the Sony GPS-CS1 simply need to be connected to the PC using a USB cable and they will appear as a removable drive. With these types of devices Downloader Pro will be able to find the track log files when the "Search removable drives" option is selected.
Many other GPS devices can't be connected directly to a PC as a removable drive and it is necessary to download the track log files to the PC. With this type of device you need to download the track log files to your PC and enter the location of the track log folder in the GPS settings dialog before downloading your photos.
Downloader Pro reads standard NMEA track log files with a .log or .nmea file extension and GPX or Garmin ForeTrex XML files with a .gpx or .xml file extension.
Downloader Pro can generate a track log file that can be viewed using Google Earth or online using Google Maps. To do this simply select the type of track log files you require and specify an output folder where Downloader Pro should write the files. Google Earth track log files have a .kml file extension and can be viewed by double clicking on the file in Windows Explorer. Google Maps track log files are web pages and have a .htm file extension. They can be viewed in a web browser by double clicking on the file in Windows Explorer.
Please note: Google Earth needs to be installed on your computer in order to view Google Earth track log files. A free download is available on the Google Earth web site. If you wish to display Google Maps on your website you will need to obtain a Google Maps API key from http://www.google.com/apis/maps/ (this is free for consumer use) and enter this in the "Google Maps Key" field in the GPS Settings dialog.
GPS devices are typically accurate to around 10 or 20 meters and usually write track log data at regular intervals e.g. every 15 secs. Some GPS devices also store altitude data in the track log file but this tends to be less accurate the the positional data (latitude and longitude). Downloader Pro reads the time the picture was taken using the shooting data stored in the image and uses this to interpolate the position using the location data stored in the track log file.
A summary of the GPS track logs available can be displayed by selecting "Check GPS track logs" from the Edit menu. This will display a list of all the track logs found, the number of GPS fixes they contains and the date and times of the oldest and newest fixes in the log.
A summary of the GPS data available for a particular image can be displayed by right clicking on the image and selecting "Check GPS data". This will display the filename, image date and time, date and time adjusted to UTC, the name of the track log and latitude, longitude and altitude data if available. The place name data obtained from www.geonames.org will also be displayed if this option was selected in the GPS setup dialog. The screenshot below shows an example: