How to convert value of unwrapping interferogram (Sentinel-1)?

Vania891 · September 29, 2015, 7:27pm

As the values of the unwrapping interferogram deployed convert into displacements that are measured in meters?

mengdahl · October 4, 2015, 11:05am

This pdf-book is a good introduction to SAR Interferometry:

Vania891 · November 6, 2015, 3:30am

How to convert the relative values of the unwrapped phase in the absolute values for the displacements in the program s1tbx?

mengdahl · November 6, 2015, 11:20am

See equation 2.6 in here: http://www.esa.int/esapub/tm/tm19/TM-19_ptA.pdf

(this assumes you have a differential interferogram where the phase is directly related to displacement/atmospheric artefacts)

Vania891 · November 9, 2015, 6:19pm

If I understand you correctly, it follows from 2.6 to calculate the displacement (d)? The values for Δф taken from the unwrapped phase? The result will be displacement in millimeters values (if the wavelength (λ) will be specified in millimeters)?

huijungw · January 19, 2016, 1:48am

How can I know the wavelength is in millimeters or meters? I still confused about the displacement in which unit.

Ben · January 19, 2016, 2:41am

if you use mm in your equation for c band wavelength, then of course the resulting value is in mm. or else if you use the phase to displacement tool, it should be meters as indicated in the pixel info.

huijungw · January 19, 2016, 3:02am

thanks. I use the phase to displacement tool, and now I know the displacement is in meters.

agruno · March 31, 2016, 10:54am

in Sar edu tutorial show other equation. is it wrong for sentinel-1?

Ben · April 4, 2016, 2:19am

trigo functions are accepted in radians in snap. its the same.

agruno · April 4, 2016, 12:30pm

Yeap, but values between this function and Sanp command “Phase to displacement” are different.

gabrielaquintana77 · September 6, 2016, 7:33pm

Hi all

I need my results in mm, how I can make this ???

Thanks for advance

agruno · September 6, 2016, 7:54pm

Band math multiply band to 1000

agruno · October 3, 2016, 10:08am

Hi

I was read source code for Phase to displacement function

github.com

senbox-org/s1tbx/blob/master/s1tbx-op-insar/src/main/java/org/esa/s1tbx/insar/gpf/PhaseToDisplacementOp.java

/*
 * Copyright (C) 2016 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.esa.s1tbx.insar.gpf;

import com.bc.ceres.core.ProgressMonitor;
import org.esa.s1tbx.insar.gpf.support.SARUtils;
import org.esa.snap.core.datamodel.Band;

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As I understand the equation is disp=-(UW_phasewavelength)/(4pi)
But in my picture is also mulitiplied with cos(rad(incident_angle)) whitch are name as (LOS to vertical factor). Why itis not done by Snap Phase to displacement function?

Additionaly using band math for current equation (-(UW_phasewavelength)/(4pi)) the results are oposite sign as phase to dispalcement function that used Snap function

junlu · October 3, 2016, 6:00pm

Hi,
The current PhaseToDisplacementOp computes the LOS displacement only. We will update the operator to output both vertical and horizontal displacements to make it more useful. To determine the unit of a band, you can always right click on the band and select Properties.

Thanks,
Jun

dsmilo · July 7, 2017, 2:56pm

Hi @junlu, has the PhaseToDisplacementOp been updated yet? I need to know if I should be manually converting LOS displacement to vertical displacement or if it’s done already through the tool?

Thanks!

mauleon.fb · August 4, 2017, 12:42am

Hi. yes when will snap be updated so that phase to displacement can show vertical and horizontal displacement? im using snap 5.0

Tomcater · January 4, 2018, 12:25pm

Please make these updates ASAP.

inan · June 18, 2020, 3:58am

Hi agruno, I tried to find this tutorial searching sar-edu, but I couldn’t. Would you please share the link if you can still reach it?

ABraun · June 18, 2020, 4:01am

It is now here: https://eo-college.org/resource/insar_deformation/