Biomedical Engineering Reference
In-Depth Information
Digital Image Processing for the Thermal
Images to Find Land Cover
and Vegetation Density
Pragyan Jain and D. Dutta
Abstract Land surface temperature (LST) on spatial and temporal domain controls
vital physical, chemical, and biological processes on Earth-atmosphere system. It is
also an important parameter at regional scale for energy budgeting and global
circulation. Surface temperature at an instant is controlled by a large number of land
surface and atmospheric phenomena viz., surface energy balance, atmospheric state,
thermal properties of surface, and subsurface medium along with sensor calibration
parameters. Hence, understanding the interaction of outgoing long wave radiation
with each of these components is important to model LST precisely. The process of
retrieval of LST from satellite data starts with radiometric calibration followed by
correction for atmospheric water vapor, aerodynamic transfer function, surface
emissivity as well as combined effects of viewing geometry, background, and
fractional vegetative cover. Once the approximation of LST is done, it needs to be
evaluated with respect to ground based measurement. In the present study, Landsat 7
ETM+ high gain thermal data was used to examine the relationship between dif-
ferent types of surface cover and vegetation density with sensible heat flux derived
from inverse Planck's model. Seasonal dynamics of LST under the similar land
cover and vegetation condition was also examined. Large dynamic range among
different land cover types was found in August (59K) in comparison to May
(22K). The LST is highest for salt affected and barren lands during May and
August, respectively. In contrast, water body appears colder in both the seasons. The
result shows that there is strong relationship with surface cover and LST. Vegetation
density in the nonvegetated areas does not show any distinct pattern, however, it
P. Jain (
&
)
Gyan Ganga Institute of Technology and Sciences Jabalpur, MP 482003, India
e-mail: pragyanjain@rediffmail.com
D. Dutta
RRSC (East), NRSC, Indian Space Research Organisation Rajarhat, New Town, Kolkata
700 156, India
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