Phase to elevation problem

Microwave Toolbox Interferometry
#1

Hi I tried to used phase to elevation but my output is all zero this is my step

  1. Coregistration
  2. Interferogram formation
  3. Goldstein Phase Filtering
  4. Phase unwrapped by snaphu
    5.import the unwrapped phase
  5. phase to elevation

Are there any step to add or any step that i skip

Thank you

#2

did you have a lookk if the unwrapped interferogram was computed correctly?

#3

I think so

I set the snaphu export in TOPO mode

and this is the result after i import it back

subset_0_of_RS2-SLC-F1-ASC-28-Feb-2016_11_Stack_ifg_flt1_Unw_Phase_ifg_28Feb2016_03Jun2016|nullxnull
subset_0_of_RS2-SLC-F1-ASC-28-Feb-2016_11_Stack_ifg_flt1_Unw_Phase_ifg_28Feb2016_03Jun2016.bmp1044×692 2.07 MB

#4

maybe the DEM quality is bad at this location. Did you try another one, e.g. SRTM 3ArcSec?

#5

Same as my problem.

#6

Hi Sir…

It is OK that phase to elevation uses a digital elevation model in reference height calculation but how we know which DEM is the best to use over our area of interest to do unwrapping?

We have many DEM to use here to convert phase to elevation with different resolutions and in different times.

dems to unwrapped
dems to unwrapped539×547 32.2 KB

If we use Sentinel-1 over polar area to make DEM, then I have below options:

ACE30

Copernicus 30 m

Copernicus 90

Arctic DEM (which is not here)

GETASSE30

They have different resolutions and I do not know what criterias should the DEM have to be a good candidate for using in unwrapping? Its resolution should be near to my data? its time should be near to my data?

#7

currently, the most precise is Copernicus DEM 30 - and it’s globally available. But the main determinant for the quality of your result is how well topography is represented in your interferogram.