3.4. Spectroradiometer field measurements
During a field trip in 2011, 40 disturbed soil samples from
about 1.0 to 1.5 m depth open pits were collected through a
stratified random sampling technique. The sample locations
are representative of all rock types within the study area and
are located inside the buffer area of 25 km and an additional
buffer of 5 km around the road (Fig. 6). Samples were chosen
to evaluate the spectral reflectance of the selected ASTER
band combination through building the spectral library for
the study area based on the spectral signatures measured. In
addition, they were used for further calibration to support
detailed remote sensing analysis. Soil reflectance spectra were
obtained using the ASD field spec full range spectrometer
(http://www.asdi.com) that covers the spectral range of