IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”,
was decreasing with the incidence angle with some undulations.
The maximum values of R? (coefficient of determination) were
observed as 0.828 at 30°, 0.561 at 20° and 0.759 at 20°
respectively, for three sets of reading. The best suitable angle for
operation of sensor was found between angle 20° and 30°. In
Fig. 4, for HH- polarization, the values of R? were much
undulating with angle as compared to VV- polarization. The
maximum value of R° was 0.830 at 30°, 0.851 at 20" and 0.928
at 25°. Hence, for HH- polarization, the best suitable angle of
operation of sensors onboard satellite was found to be in the
angle range of 20° to 30° for narrow leaf crop Paddy.
4, CONCLUSIONS
Reflectivity/scattering coefficient was found not only
higher magnitude but also higher angular variation at the
healthy and early growth stage of the crop in all the
observation made for three sets of reading for VV- and
HH- polarization.
At the completely ripe stage of crop, not only lesser
reflectivity/ scattering but also lower angular variation was
observed for both like polarization.
Due to an increase in the roughness such as increase in
number of leaf per plant, their size and random orientation,
crop height etc. reflectivity/scattering coefficient
decreased for both the like polarizations.
From the figures 3 and 4 discussed above, the best suitable
angle range for the operation of sensor for the
investigation of scattering coefficient was obtained 20° to
30° for the VV- & HH-polarization.
A comparison of angular variation of scattering coefficient
was made with other research workers (Sharma and
Singh,1992[6], Ulaby et al., 1975[7], Bush and Ulaby,
1976[8], Ulaby et al., 1982[9], Fung and Eom, 1985[10]
and found that the nature of variation is same. No claim in
comparing the magnitude with other reported results was
made due to sensitivity of our system and the changes in
climatic and environmental conditions.
These results obtained through ground based bistatic
scatterometer system indirectly provide the reference data
for the satellite-borne remote sensors. These results
provide the most suitable look angle for the operation of
sensors onboard satellite to obtain information
economically about the earth's surface.
ACKNOWLEDGMENT
Prof. D. S. Chauhan, Vice-chancellor, Technical University,
Uttar Pradesh is gratefully acknowledged for his constant
encouragement throughout the work.
[1]
[2]
[3]
REFERENCES
Ulaby, F.T., Moore, R.K. and Fung, A.K. "Microwave
Remote Sensing: Active and Passive", vol. III, From
Theory to Applications Dedham, MA: Artech House,
1986.
Pampaloni, P., and Poloscia, S., IEEE Trans. Geosci.
Rem. Sens., vol. 24 pp. 900-905, 1986.
Wegmuller, U., Int. J. Rem. Sens., vol 14, pp. 871-
883, 1993.
[4]
[5]
[6]
[7]
[8]
[9]
[10]
". Hyderabad, India;2002
Freeman, A., J. Villsenor. J, Klein JD.
Hoogeboom, and J. Groot, Int. J. Rem. Sens. vol. 15,
pp. 1799-1812, 1994.
Resenthal, W.D., Blanchard, B.J., Photogram. Eng.
Rem. Sens., vol. 50.no.4, pp. 461-468, april 1984.
Sharma, S.K., and Singh K.P., Adv. Space Res., Vol.
12, no.7 pp. (7) 73-(7)76,1992.
Ulaby , F.T., Bush, T.F. and Batlivala, PP.1EEE
Trans. Ant. Prop. vol. AP-23 no. 5, pp. 608-618, 1975,
Bush, T.F., and Ulaby, F.T., IEEE Trans. Ant. Prop.,
Vol. AP-24, no. 3 pp. 269-276, 1976.
Ulaby, F.T. Moore; R.K., and Fung, A.K. "Microwave
Remote Sensing (Active & Passive)", Addison
Wesley, vol. 2 pp. 1064-1982
Fung, A.K. Eom. HJ., IEEE Trans. Geosci. Rem.,
Sens., vol., GE-23, no. 5, pp. 768-775, 1978.
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