Ground displacement values

Microwave Toolbox
#1

Good afternoon,

I am looking at ground displacement along gas pipelines using sentinel-1 data. I have produced a series of image pairs and I can average them over time to get an idea of ground displacement. I followed various tutorials using the same imagery and I feel confident that I have processed my images correctly. I do however have have some errors in the data which can be summed up as…

  1. I have extremely high and low values (ranging from -500 mm to +500 mm)
  2. These values seem to occur over the whole image.

Now I can only think of three reasons for this →

1 - the processing was done incorrectly. I think this is highly unlikely as I carried out the image processing the same way as the tutorial. Also when I saw possible error I redone the processing with the same occurance.
2. Error in either of the images upon capture.
3. A calculation to correct the offset.

Has anyone come across something like this? I tried searching, but I couldn’t find an answer.

Cheers,

Ayelet.

#2

have you seen these?

Could it be that your study area is covered by forests? Maybe you can share some interferograms.

1 Like
#3

Thank you I will look through those links.

The areas is a pipeline route in Scotland where there are some areas classified as woodland, but the majority of the route is on improved grassland.

I will put some images together to have a look at later tonight.

#4

Hello. Most images I feel are Ok for the data, but some appear like this one which do not give the confident values.

img_error
img_error1374×903 398 KB

#5

I agree that this one is not usable.

How does a standard inteferogram (before unwrapping) look like?

#6

This is the IW2 before bursts before subsetting and unwrapping.

The images are -

S1A_IW_SLC__1SDV_20160120T062952_20160120T063020_009574_00DECB_D8EF - bursts 4-8
S1A_IW_SLC__1SDV_20160201T062950_20160201T063017_009749_00E3EF_0D05 - bursts 5-9

Whenever I have had images that have looked like this after unwrapping I have alway repeated the process with sadly the same outcome.

before_unwrap
before_unwrap1287×879 679 KB

#7

doesn’t look too bad, but it could contain some atmospheric contributions. Did you apply multi looking and filtering as well?

#8

This is before filtering. I haven’t used multilook on my images. Before unwrapping I always deburst and then apply goldstein filtering.

Is it worth applying multi look (i guess after deburst and goldstein) and then unwrap to see if this improves the image?