Making interferogram for TANDEM-X bistatic mode

marjanmarbouti · November 14, 2018, 3:33pm

Ok…l managed to make it by your help but lets explain my step to be sure, everything is OK;

In ‘map projection definition’, I left stuff like below (figure1);

Then my result is saved in ‘BEAM-DMAP’ format (figure2):

fihure2.
then I converted unwrapping file to elevation(figure3);

Figure 3.

And the result is here (figure4);

Figure4.
Is it OK?

ABraun · November 14, 2018, 3:34pm

very good!
I want to be mentioned in the publication then

marjanmarbouti · November 14, 2018, 3:35pm

Exactly, you helped me a alot. It is my pleasure:slightly_smiling_face:.

marjanmarbouti · November 14, 2018, 4:00pm

Some more notes:

How can compare my elevation result with ‘ASTER DEM’. There is a option to adding band for ‘ASTER DEM’ but it is empty. Shall I subtracted the mosaic I made from my elevation result for checking quality?
You told me:

As a last step, you can apply Tange Dopper Terrain Correction so both elevations are projected into a coordinate reference system Then you can stack them and compare the elevations.

Shall I do it now?
I tried to do it (figure 1) but them my result is like this (figure2). I think something is missing in image.

figure1.

Figure2.

marjanmarbouti · November 14, 2018, 4:06pm

Another thing that is weird for me is here;
Why when i applied terrain correction by using external file, the result is bigger that my elevation result. Please look at below;

ABraun · November 14, 2018, 4:11pm

Only use the elevation generated by InSAR as the input (as you did)
Using the ASTER here is totally fine. Make sure you check “DEM” in the terrain correction step. This writes the ASTER DEM in UTM coordinates into your target product so you can compare later.
Uncheck “Mask out areas without elevation”

If you do this with the InSAR elevations of both dates, the results will be of the same size and coordinate system and then you can select “Radar > Coregistration > Stack Tools > Stack” to bring them into one final product.

marjanmarbouti · November 14, 2018, 10:05pm

I made elevation result and the ASTER DEM in UTM coordinates (figure1) but it seems a little strange although I did not work with DEMs but why the ASTER DEM has DEM over some area of ice and does not have DEM over other parts?

ABraun · November 15, 2018, 4:45am

Have you checked how the ASTER dem looks in the mosaic?

Are you sure what we see is not the ACE30?

ASTER has 30 meters spatial resolution which is resampled to the resolution of the TDX data.

marjanmarbouti · November 15, 2018, 8:23am

This is something that I got from mosaic.

marjanmarbouti · November 15, 2018, 8:34am

I also put it on google earth and seems ok about location.

ABraun · November 15, 2018, 8:36am

does it really look like this in your study area?

marjanmarbouti · November 15, 2018, 8:50am

This is the image I have (green one).

I am trying to make a KMZ file from my result to see, if it is matched or not but then it gives me this error.

marjanmarbouti · November 15, 2018, 8:51am

This is that area and is matched with DEM.

marjanmarbouti · November 15, 2018, 9:07am

The area is right but I do not know why ASTER is in course resolution.

I downloaded this one,
https://search.earthdata.nasa.gov/search/granules?p=C197265171-LPDAAC_ECS&q=aster%20gdem&ok=aster%20gdem

Is it right?

marjanmarbouti · November 15, 2018, 9:26am

Another idea, I made a mosaic and I think the resolution was changed after making mosaic.
Yes. Now I got the point, making mosaic reduces resolution.
Any idea about it?

ABraun · November 15, 2018, 10:17am

that’s possoble. You can use the measure tool to see how large the single pixels are.
I see that you have just updated your post. Strangely, the DEM was resampled for mosaicing.

marjanmarbouti · November 15, 2018, 10:18am

No the problem is with mosaicing…look at this

ABraun · November 15, 2018, 10:21am

I just tried it with SRTM and they area also resampled to a lower reslolution.

marjanmarbouti · November 15, 2018, 10:38am

I found its solution. We should manually adjust it.

ABraun · November 15, 2018, 12:24pm

good that you found a solution.
Orthorectifying the DEM doesn’t make much sense to me. But as long as the result is not distorted, everything is fine.