VanZyl decomposition Matlab code

pari · September 12, 2020, 3:47pm

Hi Everybody,

I am looking for Vanzyl three components decomposition code for Matlab.
I should not use SNAP or other software because I am applying decompositions on forest stands. So I need the code to run in Matlab. If anyone has this code, please help
Thanks

ABraun · September 12, 2020, 4:21pm

this is how it is implemented in SNAP:

github.com

senbox-org/s1tbx/blob/master/rstb/rstb-op-polarimetric-tools/src/main/java/org/csa/rstb/polarimetric/gpf/decompositions/vanZyl.java

/*
 * Copyright (C) 2015 by Array Systems Computing Inc. http://www.array.ca
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option)
 * any later version.
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see http://www.gnu.org/licenses/
 */
package org.csa.rstb.polarimetric.gpf.decompositions;

import org.csa.rstb.polarimetric.gpf.support.QuadPolProcessor;
import org.esa.s1tbx.commons.polsar.PolBandUtils;
import org.esa.s1tbx.commons.polsar.PolBandUtils.MATRIX;

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Can you specify why you canot use SNAP for this?

pari · September 12, 2020, 5:32pm

Thank you for the SNAP codes, I am not sure can I use these codes in Matlab or not (I will comment it).
Using SNAP, the decompositions will be applied to each image pixel. In other words, the results are at pixel level. When we are extracting the values for forest stands (stand-level processing) so we can not use SNAP.

ABraun · September 13, 2020, 6:48am

SNAP is mainly based on java so the code is not directly transferable. But maybe it helps you to implement it in matlab language.

Is it an option to calculate the decomposition at the pixek level and then use spatial statistics or create object features on the forest stands (e.g. as polygons)?

pari · September 13, 2020, 2:13pm

We talking about two options for calculating PolSAR features on stand level. The first one is calculating pixel-wise features (linear or nonlinear) followed by averaging. The second alternative is intensity averaging followed by PolSAR feature calculation. These options can be equivalent only if all operations in PolSAR feature calculation are linear. However, this is not the case. Thus, the “first” option is inadequate.