I am new in SAR data processing. I have an ALOS PALSAR PLR SLC L1.1 data scene which was downloaded from ESA Database. This datset has not coordinate properties and I want to use this data for Polarimetric classification purposes for geologic mapping. First I must geocode and georeference the dataset. I am using SNAP 64.5.0
Could you please help me?
there are tutorials for this purpose:
Multi-looking and speckle filtering are optional but calibration, deskewing and terrain correction are mandatory.
Hi I used that but result has not coordinate!
We need more information to be able to help you.
What steps did you undertake so far? How do you see it has ‘no coordinate’? Is it placed at a wrong location or at the 0,0 cordinate? Did you open it in another software? Do you get any error messages?
Thanks for your comments.
It locates at 0,0 coordinate.
I used the “ALOS PALSAR Orthorectification Tutorial” and step by step as below:
3- Speckle Reduction
5- Terrain Correction
With which software do you open your product?
Did you chose a specific coordinate system at the TC step?
I used SNAP.
when running Terrain correction, I recieve an error which is attached to previous post.
Try to use Range Doppler Terrain Correction instead of SAR Simulation Terrain Correction.
Also, try Deskewing before Multi-Looking.
If both does not work, fully skip the multi-looking and use Range Doppler TErrain Correction.
Please name all steps one by one.
- Range Doppler Terrain Correction
You can apply speckle filtering afterwards if your data requires it.
some ESA products have been reported to cause problems in SNAP, please have a look here:
If you have the chance to check, please test a PLR SLC L1.1 product from ASF vertex to see if it is caused by the file structure of ESA.
I am trying to generate DEM from ALOS PALSAR data. Please tell the required steps to generate the DEM.
I tried generating interferogram directly after coregisteration but it gave wrong output. When i tried coregisteration -> multilooking -> interferogram generation , it gave an error and it said input should be slc product. Please tell all the steps requied from intials if i have a pair of ALOS PALSAR data.
Multi-looking destroys the phase information which is needed for interferometry so you have to skip this step.
Did the coregistration work?
Yes the coregisteration worked. So i should generate the interferogram directly? without any kind of preprocessing?
actually yes. You can later filter or multi-look the interferogram.
Ok. Iactually have one more cofusion. While data coregisteration, there are various options there. what coregisteration should i perform?
the one that matches your data There is no right or wrong - it depends on resolution, terrain and temporal baseline of the data.
Don’t just press buttons, try to understand what these parameters mean. The manual is a start:
This publication also gives a nice overview:
well, after generating the interferogram, what further steps are required in ALOS PALSAR data to generate correct dem?
this forum is full of answers, you just have to read them.
- Example for Sentinel-1 data: The Order of DEM Creating Steps (you can skip the debursting)
- General discussions on DEM generation: DEM generation
- Tutorial for SAR interferometry with S1 data: http://sentinel1.s3.amazonaws.com/docs/S1TBX%20TOPSAR%20Interferometry%20with%20Sentinel-1%20Tutorial.pdf