Dear All,
We need to calculate the NRCS values of the particular scene from the SAR image. Specifically we need to differentiate NRCS values of VV-polarization and VH-polarization. In order to accomplish this work, we refer the document “Radiometric Calibration of S-1 Level-1 Products Generated by the S-1 IPF”. While doing this work, I had the following doubts.
Digital number:
1. Digital number represents which value?
2. This value is difference from the actual pixel value. That is if we download the image and read it in MATLAB it shows different values.
3. Further, Why this DN value is same for all pixels? This is representation is illustrated in the following image.
SigmaNought:
1. Why sigmanought, betanought and gamma values are same for VV and VH polarization? If these values are same in both polarization, then there is no meaning right? This issue is given in the following figure.
2. Further, Is beta value same as DN?
Pixel:
1. Is pixel in the calibration vector denote exact pixel value or else from - to values? (ie) if pixel 40 means - 0 to 39. If it is not what will be the values for intermediate pixels?
Line:
1. Same doubt as in pixel. Is line in the calibration vector denote exact pixel value or else from - to values? (ie) if line 668 means - 0 to 667. If it is not what will be the values for intermediate lines?
NRCS calculation:
1. If I have to calculate the NRCS value of the particular region, for example, I need to calculate the NRCS value of the pixel number 8720 and the line number 5300, then no.of.pixels in that region is 5300 x 8720 right? If I am wrong kindly provide the way.
I have these doubts. Kindly clear my doubts. Thanks in advance.
Thanks and Regards,
M.Shanmuga sundari.