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

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

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

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

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)

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

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

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.

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

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

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

Yeap, but values between this function and Sanp command â€śPhase to displacementâ€ť are different.

1 Like

Hi all

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

Band math multiply band to 1000

Hi

I was read source code for Phase to displacement function

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

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

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 itâ€™s done already through the tool?

Thanks!

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