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Image Processing
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The Analytic of Remotely Sensed Digital Image
4 Disintegration of pixel's remotely sensed data value
As we review equation (1) and equation(6), we can get the following expression that presents the relationship between the original remotely sense data
 and the remotely sensed component of solar direct light
 of pixels;
In the similar way, the relationship between the original remotely sensed data
(DNij) and the remotely sensed component of sky-scattering light illuminance
DDij of pixels
Suppose the Band 4 original data value on a remotely sensed image are as follows;
Then :
Because pixel's remotely sensed data value of
APR(DAij) depend on the atmospheric conditions and have no relationship with the ground features, the expression
(DNij-DDij)in the equations is the atmospheric correction in traditional remotely sensed image processing.
For the sake of simplification, all above discussion is based upon the assumption that the surface is of Lambertian feature. But the conclusive expressions are also appropriate for the non-Lambertian surface, because the coefficients, Fij, Gij and Gij in the equation are computed directly based on the equimultiple change of the same pixel's ground irradiance (the directions of incidence and reflection are same either on natural ground surface or on horizontal ground surface), don't involve the directional reflection.
5.Composition and Decomposition of Remotely sensed digital image
Being Have the expression of pixel's remotely sensed data value with the three components of the solar direct light, sly-scattering light illuminance and atmospheric path radiance, we can now resolve the original remotely sensed digital image light illuminance (SSI) image and atmospheric path radiance(APR) image.
Suppose the original remotely sensed image is defined as:
| G(i,j) |
i=1,2,.....,n; |
j=1,2,.....n. |
The solar direct illuminance (SDI) image is defined as:
| Gs(i,j) |
i=1,2,.....,n; |
j=1,2,.....n. |
The sky-scattering light illuminance (SSI) image is defined as:
| GD(i,j) |
i=1,2,.....,n; |
j=1,2,.....n. |
The atmospheric path radiance(APR) image is defined as:
| GA(i,j) |
i=1,2,.....,n; |
j=1,2,.....n. |
then
Where i=1,2…….,n; j=1,2…..,m.
The image composition and decomposition can be realized by the above calculation point by point.
For the sun light is a kind of strong-directional non-polarized light, the SDI image can be used in research of direction reflection of ground surface features. The sky-scattering light is anisotropic random polarized, its corresponding remotely sensed image, which is free from shadow disturb, can be applied in research of computer identification and classification. The remotely represents the difference of atmospheric environment monitoring.
In conclusion, the different kind of components of natural light shows different characters. The analytic of remotely sensed image plays a unique powerful role in the research of remote sensing mechanism, and ground surface radiant energy quantitative analysis.
Reference
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1.Li Xianhua, Correction of Terrain Influence in remote sensing Information, Journal of Topography, May, 1986,15(2)
- 2.Li Xianhua, Calculation and emendation of diffusion irradiant energy of Remotely sensed Data on upland condition, Remote sensing Technique and Application,Mar,1992,7(1).
- 3 Li Xianhua, Inversion Calculation of the Pixel's Surface Reflectivity of the remotely sensed data , Environmental Remote Sensing, Dec, 1993,8(4)
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