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GeoSnitch for iOS gathers location data for embedding by ShutterSnitch  
Tuesday, June 5, 2012 | by Rob Galbraith
GeoSnitch, a new app for the iPhone, iPad and iPod touch from 2ndNature, tracks the position of your device and then creates a geolocation file which can be imported by ShutterSnitch, our longtime favourite iOS app for receiving pictures from a wireless camera. ShutterSnitch then reads the geolocation data and embeds it into corresponding picture files. For ShutterSnitch users, it's a slick and simple way to put location information into pictures within the app's collections. In addition, the files created by GeoSnitch can be read by any other geolocation software capable of parsing .kmz documents, such as Google Earth.

Introducing GeoSnitch

GeoSnitch is straightforward to use. Launch it, press the record button and tracking is underway. The app queries the iOS device's location once every second, then creates a new entry within a KML-format file that includes latitude, longitude and altitude plus a time stamp (heading and tilt are also included within each entry but are fixed values currently).

Location tracking is stopped automatically at user-selected intervals between 30 minutes and 24 hours, or ended manually from within GeoSnitch. Then, the .kmz file that's created can be passed to ShutterSnitch for picture embedding, or it can be sent elsewhere as an email attachment.

When ShutterSnitch receives a .kmz file, it scans its collections for pictures whose capture times match the time stamps in the file. Then, it presents a screen in which found pictures can be selected and geotagged (the location data is inserted into GPS EXIF tags within the image).

When ShutterSnitch later encounters a geotagged picture it will optionally display its location within a resizeable map area that's attached to the thumbnail strip.

The screenshots below show some of the process and the outcome, including:
  • The tracking of location by GeoSnitch and the resulting .kmz recordings
  • Selecting and geotagging pictures
  • A picture file, with embedded geolocation info provided by GeoSnitch, being displayed in ShutterSnitch on the iPhone and both ShutterSnitch and iPhoto on the iPad
  • A Google Maps view of the same latitude and longitude coordinates
(The Nikon 1 V1 JPEG shown in the screenshots can be viewed/downloaded here.)

GeoSnitch
Recording and .kmz files
Embedding and result
ShutterSnitch on iPad
iPhoto on iPad
Google Maps
Things to note
  • ShutterSnitch will embed location data into JPEGs only.

  • When ShutterSnitch embeds the location data it also re-compresses the JPEG image, which can lead to a slight loss of picture quality. This will be a deal stopper for some.

  • Once location recording is enabled within GeoSnitch, the app does not need to be in the foreground and the screen does not need to be on for the app to track the device's location. As long as GeoSnitch is not forced to quit from the multitasking bar it will continue its location monitoring until it's told not to, either when the automatic recording time limit is reached or you press the start/stop toggle within the app.

  • Constant location tracking can use a lot of battery power, particularly if you're using an older iPhone. My iPhone 4S, however, is able to run for hours and hours with GeoSnitch actively tracking its location in the background, even when that location is continually changing. Same goes for my third-generation iPad (tracking based on Wi-Fi exclusively, as I don't have an iPad with cellular data capability). In one test of my previous phone, an iPhone 3GS with a relatively new battery, it went from fully-charged to dead within four hours of switching on location recording in GeoSnitch, even though the screen was kept off for most of that time.

  • The accuracy of the location given to GeoSnitch by the iOS device will vary. An iPhone, or the cellular data version of the iPad, can determine location from GPS data as well as cell tower and Wi-Fi hotspot proximity, and therefore will deliver the most consistently true idea of where the device is at that moment. A Wi-Fi only iPad or iPod touch rely on Wi-Fi hotspot proximity alone to determine location, which means accuracy will be all over the map (pun intended).

  • GeoSnitch queries the iOS device for location data once every second. An iPhone, or the cellular data version of the iPad, will generally update the device's location at least as often as this, while a Wi-Fi only iPad (and presumably the iPod touch too) seems to perform location updates at less frequent - and varying - intervals. So, even though GeoSnitch is asking the iOS device for its location once every second, the freshness of that location data is determined by the iOS device itself, on its own schedule.

  • As with other similar geotagging solutions, it's imperative that the camera's clock be set correctly, so that the capture time in the picture file can be matched up to a time stamp within entries in a GeoSnitch .kmz file. ShutterSnitch, during the geotagging step, does enable you to enter a time offset, to account for capture time errors. But if you've dealt with this previously, you'll know that fussing with offsets is a pain best avoided by ensuring the camera is on the right time before taking pictures.

  • As of GeoSnitch 1.0, each entry in its .kmz files contain latitude, longitude, altitude, heading, tilt and a time stamp. Currently, the heading and tilt values don't change and are there just to give Google Earth an idea of where to "look" when displaying GeoSnitch-tracked locations. As of ShutterSnitch 2.4.1, only latitude and longitude are embedded into pictures.

    Developer Brian Gerfort indicates that near-term updates to GeoSnitch and ShutterSnitch will broaden the data both tracked and embedded. GeoSnitch will begin to record speed, and the heading field will no longer be a fixed value. ShutterSnitch will gain the ability to embed altitude, speed and heading. (Tilt will not be embedded at any point since it's not an EXIF GPS field; as mentioned earlier, it's included in the .kmz files for those who want to open them in Google Earth.)
GeoSnitch is available now for US$.99 (or approximate equivalent in other currencies) from the iTunes App Store on your computer, or the App Store on your iOS device. ShutterSnitch is US$15.99 (or approximate equivalent).
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