|
Size: 1411
Comment:
|
← Revision 5 as of 2010-06-15 12:18:41 ⇥
Size: 1317
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 24: | Line 24: |
| img=reshape(fromfile('ASAR_seaice_mixed_20080421_f32_1000x1000.dat',dtype=float32),(1000,1000)) close('all') ql(img,vmin=0,vmax=0.3) colorbar() title('Sea ice radar backscatter intensity') |
sigma0=reshape(fromfile('ASAR_seaice_mixed_20080421_f32_1000x1000.dat',dtype=float32),(1000,1000)) |
Radar backscatter statistics
The received power (intensity) of a radar system is proportional to the (normalized) radar backscatter coefficient
latex error! exitcode was 2 (signal 0), transscript follows:
as a function of frequency, polarization and incidence angle. The backscatter coefficient describes how much of the transmitted energy is backscattered from the surface media.
A (calibrated) ASAR image img(y,x)=I is made of the measured intensities I which can be directly related to the backscatter coefficient. A value of zero means that no energy is reflected from the surface whereas a value of one means the total reflection.
Exercise
This ASAR image shows different sea ice types. Investigate the statistic of normalized backscatter value.
- What is the mean for the two prevalent sea ice types? Select homogeneous regions to answer this question.
- Try to fit the image PDF with a superposition of two gamma distributions (ADVANCED EXERCISE).
from pylab import *
sigma0=reshape(fromfile('ASAR_seaice_mixed_20080421_f32_1000x1000.dat',dtype=float32),(1000,1000))