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Recent advances in mobile GPS/GIS mapping technology
Ashok Wadhwani Applied Field Data Systems, Inc. 16300 Katy Freeway, Ste. 250 Houston, Texas 77094 Tel: 281-5790492, Fax: 281-5790412 afdsaw@aol.com
Introduction GPS/GIS Field data collection is a perennial problem for cartographers, surveyors, engineers and researchers. Until recently, the tools available for mapping applications have been bulky in size and weight, expensive, and difficult to learn. During the past year, tremendous advances have taken place in GPS technology (receivers), data collection hardware, and field data collection software. Not only has the autonomous GPS accuracy improved, but the data collectors have become smaller, lighter, and less expensive. The software has become cheaper and easier to learn. In addition, for applications involving offsets, lower priced laser range finders have been become available. All of these advances have made the GPS/GIS data collection tasks easier, more economical and faster to complete. (See Fig. 1)  Figure 1: Mobile Mapping Advancements GPS Receivers With the elimination of Selective Availability (SA), autonomous accuracy is much better. Today, a single stand alone receiver can provide an accuracy of between 10-15 meters. These receivers are so small that they can easily fit in your shirt pocket and one can get these receivers for approximately $100. It is also now possible with the use of DGPS service to obtain sub meter accuracy in real time. (This eliminates the need for post processing). This DGPS service is available through the use of coast guard beacon receivers and satellite based DGPS service. The coast guard service is limited to the coastal areas of the country or around 50-200 miles radius of the station itself. For areas where the coast guard beacon service is not available, real time satellite based DGPS service is available almost throughout the world at reasonable cost.
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