GIS is a hungry animal and needs data. GPS is a superior way to gather GIS data. In the past, digitizing, scanning, field notes, photogrammetry were favored for populating GIS systems. These data collection techniques have limitations in terms of accuracy, attribute collection, and cost. GPS brings accurate spatial and tabular information to GIS. As a result, increased GPS accuracy, data collection functions, and productivity has now shifted the balance in favor of GPS as a GIS data acquisition tool. Data acquisition is the most costly part of a GIS system. GPS can automate and speed data collection at lower costs with savings in the range of 50%-60% over conventional methods. In addition, GPS can update and maintain GIS with greater efficiency.
The common ways to use GPS for GIS applications is feature data collection and navigation to locate features. Now a new GPS data maintenance technique allows GIS users to easily update, verify, modify features, and collect previously unrecorded features. Data maintenance will allow the user to transfer GIS files into GPS data loggers for background reference, updating, and navigation purposes. This is the start of a trend to move GIS into the field rather than move the field into GIS.
The data maintenance cycle starts by moving previously collected themes into the GPS field system, updating, moving the field data back to GIS as a newly updated theme. Features may be added, modified, deleted, and restructured. Features can be filtered in the field to concentrate on feature type, attribute value, time collected, and update status. Imported file formats include ArcView (.shp), Mapinfo (.mif), and dBase files. A box icon indicating feature status controls data maintenance: new, updated, and imported. A map display provides reference for collected and updated features with selectable cursor for choosing features for target navigation. User can navigate directly to features for updating using navigation screens.
Trimble's Pathfinder Office software supports the data maintenance function with GIS file import, file transfer to data collector, differential correction, converting updated data into a GIS format, and filter the transfer to include new, updated, and all features.
The future promises increased integration between GPS and GIS systems with much of the work being done in the field on the spot.