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Documenting the road to peace: A GIS approach
The digital photos and movies were also downloaded to the desktop computer and placed in the same folder as the exported .gml file. The digital photos (in Joint Photographic Experts Group (JPEG) format) and the movies (in Moving Pictures Expert Group (MPEG) format) store date and time information in the header of the file, as seen in Figure 3. Trimble MediaMapper uses this information to match the multimedia files with GPS data.
 Figure 3: JPEG file header The next step was to use the Add Media wizard in Trimble MediaMapper. This wizard guides you, step by step, through the process of merging the multimedia files with the GPS track file. First we added names for the media layer (the layer that contains the digital imagery) and the track layer (the layer that contains GPS data). Then we specified the folders where the digital imagery and GPS data are located. The final step was processing the data. The first part of the data processing is to calibrate the digital camera clock. This was done by taking a photo of the UTC time displayed by the GPS receiver, and then comparing it with the date and time displayed in the header information of the multimedia file. Trimble MediaMapper then calculates an offset, which is used to match each multimedia file with a position from the GPS track file. When data processing was complete, the data was displayed in the map window. We then added regional data from the Digital Chart of the World (DCW) dataset, and a geo-referenced scanned map of northern Sri Lanka to give some spatial reference to the collected data. As we wanted to update the centerline data and view it in our GIS software, we exported the data to ESRI ArcGIS. Using the Trimble MediaMapper extension for ArcGIS, we could view the multimedia images in ArcGIS for a true picture of the road.  Figure 5: Viewing a digital image in GIS software As the data collected had a far greater potential audience than those with access to ArcGIS, we wanted to convert the data into a more accessible format. We used the Export to HTML functionality of Trimble MediaMapper to create HTML pages. This allows us to display the information over the Internet or write it to a CD-ROM. A website is currently under construction. Conclusion This project allowed us to test the usefulness of a multimedia data collection system. Using a handheld GPS receiver and a consumer digital camera, we were able to collect still and moving imagery and add it to our GIS data. GPS data collection and image capture can be undertaken with less than one hour of training, making it possible for almost anybody to complete. This pilot project exceeded our expectations of being able to build a multimedia GIS database. It has been said, “a picture is worth a thousand words”. One MPEG movie demonstrated to Norwegian mine clearing experts the extent of unexploded ordnance just 10 meters from the road . In another example, an image of part of the road showed non-governmental agency workers the difficulty of shipping goods by road. Trimble MediaMapper has proven to be a versatile data collection tool that simplifies acquisition, organization, and extension of site-specific multimedia—digital photographs, audio, video, and digital documents. With Trimble MediaMapper we were able to automatically merge the source media with spatial information from GPS receivers, and build an interactive media map that is widely accessible via the Internet.
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