Some questions about radiometric calibration (beta or gamma)

s1tbx
#1

Hello,
I have some questions about radiometric calibration using various satellite images.
Calibration to sigma0 is conducted well from various satellite images such as S-1, K-5, ICEYE, etc.
Whenever I tried to calibrate to beta0 or gamma0, there were some problems.
Using S-1, everything is fine.

However, when I used other satellite images, the target band(beta or gamma) was created to the virtual band like the following picture.
image
So, I couldn’t save the target band immediately.

Is it the only solution to save virtual band to real(?) band via band math?
Or, how can I save immediately the gamma0 or beta0 band?
I prefer to use snappy than the GUI program.

Thank you.

#2

you can right-click on any virtual band and selct “Convert Band”. Then simply File > Save Product and the band is permanently stored.

FAQ: What is a virtual band?

If you only need it for further processing in SNAP, there is no need to convert, because you can also take virtual bands as inputs for subsequent steps.

#3

What is the corresponding code for ‘Convert Band’ in gpt or snappy?
Only I can find in GPT code including “convert” is convert datatype…

Is it possible to access the virtual band in python(snappy)?
Using getBandNames or other things, only the real bands are shown.

#4

sorry, I overlooked this part.

I think you can define the exact output band of the calibration operator in snappy as well.
parameters.put('outputGammaBand', True)

https://www.youtube.com/watch?v=PiU68g3WRIY&

#5

Thank you.
Even though I defined that parameter as True, I didn’t work.
But I’ll check the video. Thank you.

#6

have you seen this work around? How to convert virtual bands to real bands using snappy

1 Like
#7

Thank you. I’ll check that work too.

#8

I assume that not all output formats support virtual bands, so if your snappy code is not already saving to BEAM DIMAP or maybe NetCDF-BEAM formats you might try them.