Image Processing Reference
In-Depth Information
Field or laboratory measurements are performed with spectrally very high
resolution instruments. Spectra, or so called spectral endmembers , are usually
normalized to reflectance values and stored in a spectral database, along with an
appropriate set of meta-data. Spectral data may be combined with coordinate
information in a geo-database to provide an urban spectral cadastre. While such
data sets are abundant for many natural environments, there is still the need for
more extensive urban spectral libraries that allow selecting a great range of
very high resolution urban spectra from pre-defined sources. Once collected, very
high resolution spectral references may be resampled to the spectral resolution
of imaging spectrometers based on their band dependent sensitivity functions
(Fig. 9.3 ).
Fig. 9.3 Cobblestone pavement spectra from
laboratory measurements ( top ), resampled to
HyMap ( centre ) and Landsat TM spectral resolu-
tion ( bottom )
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