AbstractAn On-Line Positioning User Service for Geographic Information Systems Track: Land Management Author(s): Gerald Mader, Neil Weston For the past 4 years, NGS has operated the On-Line Positioning User Service (OPUS), which provides centimeter-level positioning accuracies with respect to the CORS network. OPUS users submit via the OPUS Web page upwards of 2 hours of dual-frequency GPS data and receive a positioning report by e-mail within several minutes. These accuracies utilize GPS carrier phase observations, which are generally produced by high-end GPS receivers. However, many users, particularly those in the GIS community, do not require such high accuracies and instead could satisfy most of their positioning requirements with accuracies on the order of 1 meter or less. OPUS-GIS has been designed to provide meter and submeter level accuracies using the pseudorange data produced by most low-end GPS receivers. OPUS-GIS uses the differential range solutions to improve accuracy by placing the position correctly the National Spatial Reference System (NSRS) while also improving precision by averaging the positions to 3 CORS. Gerald Mader National Geodetic Survey, NOAA/NOS 380 New York St. Redlands, CA 92374 US Phone: 909-793-2853 E-mail: andrea_garcia@esri.com Neil Weston National Geodetic Survey, NOAA/NOS 380 New York St. Silver Spring, MD 92372 US Phone: 909-793-2853 E-mail: andrea_garcia@esri.com |