2.4.4 Polarimetry
In this example, we are going to use three applications :
- the first one is SARDecompositions. This application is used to compute the HaA
decomposition. It takes as inputs three complex channels from bands HH HV and VV.
- the second one is SplitImage. Indeed, the previous application had produced an output image
made up of three channels, H a and A, and we wish to focus on the H parameter (entropy). So
we let this application split this image into three one-band-images.
- the last one is ColorMapping. The entropy image has values ranging from 0 to 1, and they can be
easily displayed by Monteverdi. But since we have a nice visualizing tool in hand, we wish we could
go a little bit further. Here comes the application ColorMapping. It is going to be used with the
following parameter settings:
- method = continuous. This parameters tells the application to use a gradient of colors to
represent the entropy image.
- method.continuous.lut = hot. We specify here the kind of gradient to be used : low values
in black, high ones in white, and intermediate ones in red/orange/yellow...
- method.continuous.min = 0 and method.continuous.max = 1. Here, the gradient of colors
must be adjusted to the dynamic of the entropy image (note: it is theoretically known
that in HaA decomposition, H ranges from 0 to 1. Generally speaking, the histogram of
Monteverdi can also be used for this purpose).
In the figure below ( 2.11), we show the obtained result, with the local contrast layer effect.