Question about Performing Radiometric Terrain Correction upon ALOS ScanSAR Level 1.5 Images

Hi GAMMA folks,

I have used par_EORC_PALSAR_geo to convert ALOS Level-1.5 images into GAMMA-supported format. However, the image geometry is GEOCODED, which cannot be used in gc_map of mk_geo_radcal processing chain. (gc_map only takes image geometry in slant range geometry).

I am wondering if it is okay to use GRD_to_SR to transform images first, then proceed the mk_geo_radcal processing chain. Is there any problem it might cause?

Really appreciate your help.

Jack

Replies (4)

RE: Question about Performing Radiometric Terrain Correction upon ALOS ScanSAR Level 1.5 Images - Added by Jack Chang about 5 years ago

Just quickly tried it. Got an error message as follow when running gc_map:

ERROR p_interp(): time outside of range: 1.01374 min: 52170.00000 max: 52830.00000

I will keep on thinking about how to deal with it, but meanwhile does anyone have idea how to work around this issue?

Thanks,
Jack

RE: Question about Performing Radiometric Terrain Correction upon ALOS ScanSAR Level 1.5 Images - Added by Charles Werner about 5 years ago

Hello,
This message suggests that the data are not in slant-range and that the state
vectors are not matching the annotation

There may be an error in reading the input data.

Are the ALOS ScanSAR images in a slant range or ground range geometry?
Perhaps the images have been converted to ground range or are ellipsoid corrected.

Please make these data available so that we can look into what options are
available.

Best regards,
Charles Werner

RE: Question about Performing Radiometric Terrain Correction upon ALOS ScanSAR Level 1.5 Images - Added by Jack Chang about 5 years ago

Hi Dr. Werner,

I am attaching the original IMG* and LED* file together with an ASCII format parameter file(ALPRS*LED.txt) in following link. Data were downloaded from Alaska Satellite Facility.

https://drive.google.com/open?id=1AILlvckF5_wH5qSdt7JTzJPVRcI3VaJS

I am also attaching mli.par (20061114.HH.mli.par) file which I obtained by using par_EORC_PALSAR_geo command. A bmp image of corresponding MLI image is also attached.
In the mli.par file, it says geometry is GEOCODED.

Thank you very much for your prompt reply.

Best,
Jack

Download all files

20061114.HH.mli.par (3.92 KB) 20061114.HH.mli.par	MLI parameter file obtained from "par_EORC_PALSAR_geo" command
20061114.HH.mli.bmp (565 KB) 20061114.HH.mli.bmp	bmp image of MLI image obtained from "par_EORC_PALSAR_geo" command

Question about Performing Radiometric Terrain Correction upon ALOS ScanSAR Level 1.5 Images - Added by Charles Werner about 5 years ago

Hello,
you cannot use GRD_to_SR to transform a ellipsoid geocoded image to get a slant
range image. this program is really only meant for ASAR ground-range images.

Ground-range data from Sentinel-1 are converted to slant range when they are
ingested. They can be geocoded from the

Best regards,
Charles Werner

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