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Project Overview
Radar interferometry is becoming one of the most important sources for digital elevation models (DEMs) and other topographic data. For example, in February 2000 the Shuttle Radar Topography Mission (SRTM) mapped the majority of the Earth's land surface using interferometry. Yet the effects of forests on the accuracy and effectiveness of radar interferometry are not well understood. At short wavelengths (X- and C-band wavelengths) the radar signals are primarily responding to the upper canopy, while at very long wavelengths the signals may reach the ground surface. |
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| This project developed a 2100 sq km DEM for a region in northwestern Wisconsin, using L-band (24 cm wavelength) interferometric radar imagery from the SIR-C system. The accuracy of this DEM was then evaluated with respect to a wide range of variables. Significant differences were found in the accuracy of elevation estimates in different forest types (e.g., red pine, jack pine, quaking aspen, and northern hardwoods). Within these types, stands with different stem diameters had different levels of elevation accuracy. A detailed study of red pine stands showed that the apparent elevation bias in these stands is a function of the interaction between multiple factors, including thinning status and stem diameter. |
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