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AN ASSESSMENT OF GROUND TRUTH VARIABILITY USING A "VIRTUAL FIELD REFERENCE DATABASE"
Citation:
Lunetta, R S., J. Iiames, J Knight, R. O. Congalton, AND T H. Mace. AN ASSESSMENT OF GROUND TRUTH VARIABILITY USING A "VIRTUAL FIELD REFERENCE DATABASE". PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING 67(6):707-716, (2001).
Impact/Purpose:
Our research objectives are to: (a) develop new methods using satellite remote sensor data for the rapid characterization of LC condition and change at regional to national scales; (b) evaluate the utility of the new NASA-EOS MODIS (Moderate Resolution Imaging Spectrometer) leaf area index (LAI) measurements for regional scale application with landscape process models (e.g., biogenic emissions and atmospheric deposition); (c) provide remote sensor derived measurement data to advance the development of the next generation of distributed landscape process-based models to provide a predictive modeling capability for important ecosystem processes (e.g., nutrients, sedimentation, pathogens, etc.); and (d) integrate in situ monitoring measurement networks with UAV and satellite based remote sensor data to provide a continuous environmental monitoring capability.
Description:
A "Virtual Field Reference Database (VFRDB)" was developed from field measurment data that included location and time, physical attributes, flora inventory, and digital imagery (camera) documentation foy 1,01I sites in the Neuse River basin, North Carolina. The sampling frame incorporated both systematic unaligned and stratified random design elements to provide
an even distribution of points across the study area and sufficient sampling site intensification to characterize under represented classes. Field sampling was accomplished during May through September of 1998 and 1999. Field crews navigated to sampling -points using Global Positioning Systems (GPS) operating in real-time (satellite broadcast) differential corrected mode. Circular plots with a radius of 36.5 meters were measured and flagged to provide 0.4 hectare plots. Field measurements were made corresponding to location and time, physical parameter and biophysical measurements. Measurements corresponding to physical parameters included, slope, aspect, elevation, percent cover of predominate land-cover type, water regime, and soil moisture condition (,descriptive), diameter breast height (DBH) and percent canopy cover wwe collected, at. appropriate. DBH was determined using a refractive lense technique, slope was measured using a clinometer, and percent canopy using both the vertical tube and hemispherical densitometer techniques. Detailed inventory of crop types, ground cover, shrubs, undcr-story tree and tree canopy constituents and relative abundances were dotermine4 for each site, as appropriate. Also, a high resolution (1040 x 940 pixels) natural color imagery series was acquired for each site,