ALOS-2 coregistration problem


#1

Hello,
when applying coregistration to ALOS-2 Images I encountered a problem. The residuals look fine but I get the error “the specific region if not null must intersect with the images bounds”. Any advice?
Thank you!


#2

Hi,
I am facing a problem while co-registration or even calibration of ALOS-1/PALSAR-1 L1.1 scenes.
The message is : ‘Input should be a SAR image’.
I have checked the metadata file and found that the values are missing.

How do I resolve the issue??

Thanks in advance


#3

how did you import your data?

SNAP requires metadata of your image if you want to use most of the SAR tools.
Open the scenes by File > Import > SAR > ALOS and select the corresponding file in order to open the image in SNAP. This will ensure that all available information (date, product, product level, incidence angle…) is available to SNAP.


#4

Hi,
I am using ALOS-1 L1.1 and not ALOS-2.
I have done the same thing, many times, but the problem still persists. I have attached a snapshot of the problem as well.

However, I am able to get the metadata using ALOS-2.

Is there an issue with the version of the software or anything else??

Thanks


#5

could it be that some parts of the product are missing?
Your screenshot indicates that the metadata wasn’t fully read by SNAP. You could also try to open the LDR file with a text editor and see if there are values in it or not. If not, I would contact the data provider.


#6

The Leader File shows all the data present.
I can process the data in other softwares such as ENVI and PolSARPro.
But for certain operations such as calibration, coregistration, etc., I am unable to open it in SNAP.

Thank you.


#7

which version of SNAP are you using?


#8

I am using SNAP 5.0


#9

Hi,
The earlier problem with ALOS-1 coregistration was solved. The error was in reading the LED file.
However, I have a problem with ALOS-2 Spotlight mode coregistration.
The process gets completed, with generation of intensity and i and q flies but the imaginary file of slave image has zero values.
How can I resolve the problem??

Thanks in advance.


#10

Hi Rosh,
could you write me, how did you solve problem with ALOS-1 coregistration? What is the error in reading LED file?
Thank you
Katerina


#11

Hi Katerina,

The LED file was corrupted because I had extracted the [S] matrix elements using PolSARPro to the same folder containing the LED file. However, if you use different folder for PolSARPro outputs there is no such errors.
After unzipping the ALOS-1 data, simply read the LED file in SNAP and follow the step for co-registration as given in the tutorial.
Hope this helps.

-Rosh


#12

Thank you, Rosh, for your swift reply.
I am using ALOS1 L 1.5 (geocoded) data for Offset Tracking application.
I downloaded the dataset in CEOS format from Alaska Facility.
After importing it to SNAP, there is some information missing (see attached image).
For Offset Tracking and I need to perform the DEM assisted coregistration before.
But it always fails, it generates an empty image in few seconds.
I think that the missing metadata information is the cause of the error. Maybe I am mistaken…
Thank you for any hints.
Katerina


#13

Hi Katerina,

Yes, you are right it is the missing info in the metadata file that prevents you from co-registration.
I was having the same issue, but like I said that was due to extracting [S] matrix in the same folder.
Although I have never used L1.5 data, I guess extracting in SNAP is same for all data types.
Have you extracted the data using any other software before importing in SNAP? If so, then that maybe the error.
You would always want to use SNAP first for all extraction.
HTH.

-Rosh