Alos palsar 2

Microwave Toolbox
#1

Hi all
I just wanted to share with all this processing flow in SNAP with ALOS PALSAR 2. All help or advice is welcome!

  1. Download the product (HH and HV polarizations)

    1
    11017×588 132 KB

    2
    2743×574 250 KB

  2. Geometric / Collocation

    4
    41366×728 204 KB

5
5428×549 13.3 KB

  1. Convert both images (HH and HV) to DB

    8
    81366×729 58.6 KB

  2. Create a new band dividing HH by HV

    10
    101366×729 361 KB

  3. Apply a speckle filter

    12
    121366×729 172 KB

On the other hand, I use the HV decibels band (created on the step 3.) to make a forest/non forest mask, but the limit (according to the histogram) is around -47 or -48 decibels.

forest
forest1121×661 201 KB

Thanks in advance for your suggestions!!

#2

Thank you for sharing, this looks nice.

Just one comment: You probably missed to add the 32 as a constant in the equation. This would probably result in the expected valid range of values (-40 to +10)
Source: Calibration Result of ALOS-2/PALSAR-2 JAXA Standard Products

#3

Thank you so mucha Andreas
The equation I’ve introduced in Band Math is this:

6
61209×412 55.7 KB

I didn’t know that was necessary a constant of 32…
So the expression would be?:
(10*Log10 (DN2) - 83 dB) +32

#4

Hm, the documentation you showed is quite clear about it, you’re right. The unexpected range just reminded me of t this additional constant, but it applies to Level1.1 data only.

So it would make sense from a mathematical point of view, but not from the theory side…

#5

As always, thank you Andreas

I have written to the ALOS PALSAR 2 support: aproject@jaxa.jp

I will keep you updated!

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