Outlier values in the DEM generated from Sentinel-1

Hello,

I constructed a DEM based on the tips in the youtube film from Sentinel-1. However, there are outlier values throughout the DEM raster (such as the attached photo). Is there a setting that can prevent such an error?

Thanks a lot.

Hard to tell at which step these were introduced.
Are these already visible in the interferogram?

Yes, there are in the interferogram.

Please share some more information. We can’t help effectively with little knowledge about your study area, the data, some screenshots…

The attachment is for the Interferometric phase after applying the Goldstein Phase Filtering.

I followed the S1TBX DEM generation with Sentinel-1 IW guideline.

Can you please check what value these have?

Did they exist before Goldstein filtering?

These black pixels exist after the Interferogram Formation. However, after TOPS Deburst are no longer in the image. But after the Goldstein Phase Filtering, these black pixels reappeared.

Value of some black pixels after the Interferogram Formation :

Product: S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg

Image-X: 12269 pixel
Image-Y: 1596 pixel
Longitude: 48°24’07" E degree
Latitude: 32°18’23" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 real
q_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.75302 coherence

latitude: 32.306416 deg
longitude: 48.401894 deg
incident_angle: 43.8738 deg
elevation_angle: 38.64624 deg
slant_range_time: 6201988.0 ns

Product: S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg

Image-X: 12323 pixel
Image-Y: 1602 pixel
Longitude: 48°24’13" E degree
Latitude: 32°18’26" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 real
q_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.46507 coherence

latitude: 32.30735 deg
longitude: 48.403664 deg
incident_angle: 43.88353 deg
elevation_angle: 38.654343 deg
slant_range_time: 6202827.0 ns

Product: S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg

Image-X: 18000 pixel
Image-Y: 2626 pixel
Longitude: 48°34’51" E degree
Latitude: 32°26’55" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 real
q_ifg_IW3_VV_05Jul2020_29Jul2020: 0.00000 imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.84030 coherence

latitude: 32.448673 deg
longitude: 48.58082 deg
incident_angle: 44.894512 deg
elevation_angle: 39.493954 deg
slant_range_time: 6291054.5 ns
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Value of some black pixels after the Goldstein Phase Filtering :

Product: subset_0_of_S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg_deb_flt7

Image-X: 1411 pixel
Image-Y: 742 pixel
Longitude: 48°02’33" E degree
Latitude: 32°13’52" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: NaN real
q_ifg_IW3_VV_05Jul2020_29Jul2020: NaN imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020_db: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.73801 coherence

latitude: 32.23111 deg
longitude: 48.04249 deg
slant_range_time: 6043569.0 ns
incident_angle: 41.973587 deg

Product: subset_0_of_S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg_deb_flt7

Image-X: 1452 pixel
Image-Y: 779 pixel
Longitude: 48°02’35" E degree
Latitude: 32°14’09" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: -89542543540224.00000 real
q_ifg_IW3_VV_05Jul2020_29Jul2020: -94444116246528.00000 imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020_db: 282.28851 intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: -2.32956 phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.72488 coherence

latitude: 32.23591 deg
longitude: 48.043045 deg
slant_range_time: 6044206.0 ns
incident_angle: 41.981606 deg

Product: subset_0_of_S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg_deb_flt7

Image-X: 3443 pixel
Image-Y: 1090 pixel
Longitude: 48°06’26" E degree
Latitude: 32°17’06" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: 89163269406720.00000 real
q_ifg_IW3_VV_05Jul2020_29Jul2020: -104058987741184.00000 imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020_db: 282.73657 intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: -0.86234 phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.89231 coherence

latitude: 32.285023 deg
longitude: 48.107105 deg
slant_range_time: 6075148.5 ns
incident_angle: 42.363976 deg

Product: subset_0_of_S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg_deb_flt7

Image-X: 6987 pixel
Image-Y: 1699 pixel
Longitude: 48°13’09" E degree
Latitude: 32°22’45" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: NaN real
q_ifg_IW3_VV_05Jul2020_29Jul2020: NaN imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020_db: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.58690 coherence

latitude: 32.37908 deg
longitude: 48.219204 deg
slant_range_time: 6130226.5 ns
incident_angle: 43.034016 deg

Product: subset_0_of_S1A_IW_SLC__1SDV_20200705_split_Orb_Stack_esd_ifg_deb_flt7

Image-X: 6887 pixel
Image-Y: 1782 pixel
Longitude: 48°12’49" E degree
Latitude: 32°23’20" N degree

BandName Value Unit
i_ifg_IW3_VV_05Jul2020_29Jul2020: NaN real
q_ifg_IW3_VV_05Jul2020_29Jul2020: NaN imaginary
Intensity_ifg_IW3_VV_05Jul2020_29Jul2020_db: NaN intensity
Phase_ifg_IW3_VV_05Jul2020_29Jul2020: NaN phase
coh_IW3_VV_05Jul2020_29Jul2020: 0.45238 coherence

latitude: 32.38884 deg
longitude: 48.2136 deg
slant_range_time: 6128672.5 ns
incident_angle: 43.0159 deg

Please check if 0 is assigned NoData in the band properties of the bands i, q, intensity, phase and coherence.
Probably these pixels are 0 and treated as NoData by SNAP. By disabling this option they might reappear in their designated color.

grafik

Dear, thank you very much.

The problem was solved with your guidance.