image co-registration process with high accuracy is needed (Li
et al., 2007). The two images were fine co-registered using affine
geometric correction based on ground control points (GCPs) selected
from image to image. The differential backscattering intensity
image was calculated using Eq. (7):
di;jðdBÞ ¼ r0i
;j;postðdBÞ r0i
;j;preðdBÞ ði ¼ 1; 2; . . . L;
j ¼ 1; 2; . . . ;MÞ ð7Þ
where di,j = pixel value to dB of differential backscattering intensity
image at image line i and column j, r0i
;j;post = sigma nought r0 of postearthquake
backscattering intensity image at image line i and column
j, r0i
;j;pre = sigma nought r0 of pre-earthquake backscattering
intensity image at image line i and column j, L, M = number of lines
and columns in the product.
In this study, differential and false color composition methods
were used to highlight the geological disasters of landslides and
barrier lakes.
Building damages in Dujiangyan city were analyzed based on
1 m spatial resolution TerraSAR-X intensity image. A pre-earthquake
QuickBird image was used to extract ancillary GIS data of
buildings and blocks. The radar backscattering coefficient was calculated
for each building. The backscattering mechanisms of damaged
and undamaged buildings were illustrated. The impact of the
orientation of buildings on backscattering intensity measured by
SAR was discussed. Generally, the backscattering intensity determined
after building collapse is likely to be lowered compared to
that obtained from undamaged building or obtained preearthquake
image co-registration process with high accuracy is needed (Liet al., 2007). The two images were fine co-registered using affinegeometric correction based on ground control points (GCPs) selectedfrom image to image. The differential backscattering intensityimage was calculated using Eq. (7):di;jðdBÞ ¼ r0i;j;postðdBÞ r0i;j;preðdBÞ ði ¼ 1; 2; . . . L;j ¼ 1; 2; . . . ;MÞ ð7Þwhere di,j = pixel value to dB of differential backscattering intensityimage at image line i and column j, r0i;j;post = sigma nought r0 of postearthquakebackscattering intensity image at image line i and columnj, r0i;j;pre = sigma nought r0 of pre-earthquake backscatteringintensity image at image line i and column j, L, M = number of linesand columns in the product.In this study, differential and false color composition methodswere used to highlight the geological disasters of landslides andbarrier lakes.Building damages in Dujiangyan city were analyzed based on1 m spatial resolution TerraSAR-X intensity image. A pre-earthquakeQuickBird image was used to extract ancillary GIS data ofbuildings and blocks. The radar backscattering coefficient was calculatedfor each building. The backscattering mechanisms of damagedand undamaged buildings were illustrated. The impact of theorientation of buildings on backscattering intensity measured bySAR was discussed. Generally, the backscattering intensity determinedafter building collapse is likely to be lowered compared tothat obtained from undamaged building or obtained preearthquake
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