I tried using SNAP for preprocessing the data, but it says ‘Source image must be a SAR product’. The files are in .(tif) format and I have converted them into >dim using exporting in SNAP, but the error is coming while doing radiometric calibration.
Also can I use a fully python based environment for the analysis?
My guess is that SNAP cannot understand the metadata of the TIF file. Converting it into BEAM DIMAP format will not restore the information which is already unavailable from the beginning.
Are there any sample products available for testing?
Thanks for the reply. I also think that is the issue. But I don’t know which platform can I use for the processing. PFA the drive link with some data. Any suggestions will be highly appreciated.
Google drive link: https://drive.google.com/drive/folders/1Ik8Uf-gTBpwmWt3W7ZO1Jq_POH5ROyki?usp=sharing
I have never heard of this data. Maybe it is worth contacting the data provider if they suggest a software or package to work with them.
The internal metadata do not contain much information
Thank you for the help.
Hi there
I am new in SAR data processing. I have an Chandrayaan-2 DFSAR SLC L1.1 data scene which was downloaded from ISRO Database. This datset has not coordinate properties, and is having a GCS_Moon_Spheroid reference system, and I want to use this data for Polarimetric classification purposes for target property retrieval. First I must geocode and georeference the dataset. I used SNAP 64.5.0, and tried doing calibration but it shows dataset is not supported. Could you please help me?
I merged both topics in here. Currently, this sensor is not supported by SNAP, but maybe someone has an idea on a work around.
Thank you so much, I really wish somebody could help.
Hi there!
I faced the same issue using SNAP for CH-2 DFSAR data. You can use PolSAR Pro software for Processing. ISRO has also developed MIDAS software for DFSAR data extraction and processing. You can try it. I am using these two software for Ch-2 DFSAR data processing.
If you have any update using SNAP please let me know.
Thank you
I am finding myself with this same issue. I am trying to work with Chandrayaan-2 DFSAR calibrated SLC images (downloaded from https://chmapbrowse.issdc.gov.in/MapBrowse/).
It would be great if in the future, SNAP could pick up these images to process them.
Chandrayaan-2 SAR calibrated data contents example:
..[ch2_sar_ncxl_20220320t150601874_d_fp_d18]
├── [browse]
│ └── [calibrated]
│ └── [20220320]
│ ├── ch2_sar_ncxl_20220320t150601874_b_brw_xx_fp_xx_d18.png
│ └── ch2_sar_ncxl_20220320t150601874_b_brw_xx_fp_xx_d18.xml
├── [data]
│ └── [calibrated]
│ └── [20220320]
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_in_fp_xx_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_xx_fp_hh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_xx_fp_hv_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_xx_fp_vh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_xx_fp_vv_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_gri_xx_fp_xx_d18.xml
│ ├── ch2_sar_ncxl_20220320t150601874_d_sli_xx_fp_hh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sli_xx_fp_hv_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sli_xx_fp_vh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sli_xx_fp_vv_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sli_xx_fp_xx_d18.xml
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_in_fp_xx_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_ma_fp_xx_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_xx_fp_hh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_xx_fp_hv_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_xx_fp_vh_d18.tif
│ ├── ch2_sar_ncxl_20220320t150601874_d_sri_xx_fp_vv_d18.tif
│ └── ch2_sar_ncxl_20220320t150601874_d_sri_xx_fp_xx_d18.xml
└── [geometry]
└── [calibrated]
└── [20220320]
├── ch2_sar_ncxl_20220320t150601874_g_gri_xx_fp_xx_d18.csv
├── ch2_sar_ncxl_20220320t150601874_g_oat_xx_fp_xx_d18.csv
├── ch2_sar_ncxl_20220320t150601874_g_oat_xx_fp_xx_d18.xml
├── ch2_sar_ncxl_20220320t150601874_g_sli_xx_fp_xx_d18.csv
├── ch2_sar_ncxl_20220320t150601874_g_sri_xx_fp_xx_d18.csv
└── ch2_sar_ncxl_20220320t150601874_g_xxx_xx_fp_xx_d18.xml
Good morning, Mr. Braun. @ABraun
Lately, I have been working on a Python script with the aim of converting Chandrayaan-2 DFSAR Moon data into the Beam-DIMAP format for use in SNAP. It is by no means a correct or professionally made piece of code, I would say, but so far it appears to work at a basic level.
One of my interests is attempting to perform interferometry using Chandrayaan-2 data. One of the issues I have run into is the co-registration of the images, as well as the calculation of baseline parameters with SNAP’s InSAR Stack Overview tool, which returns unreasonably large values (edit: fixed this, it was the line_time_interval) for pairs of images with a relatively good overlap. The slave band never gets saved correctly, for some reason.
Chandrayaan-2 data comes with satellite orbit vectors (position, velocity, etc.), but they are referenced to the lunar-centered frame rather than the Earth-centered reference frame. I suspect this may be one of the possible issues.
Another issue is that Chandrayaan-2 images tend to be extremely long in the azimuth direction and narrow in range, which may contribute to these problems. While two images may have good overlap and alignment at the beginning of the track, they may gradually diverge toward the end. I am not sure how the co-registration process works internally, but simply creating a subset over the area where the images coincide may not be sufficient.
Any support or guidance as to how to tackle these issues would be appreciated!
@ABraun Hi Andreas, I see on some online STEP forum assistance that you’re listed as a STEP moderator to “@” when needing forum help. I am trying to post a new topic covering something I need help with but don’t see a forum for. I keep getting the same response that an error has occurred. I believe it’s because I am new here and don’t have a high enough “trust level”, or so the internet is telling me? Thanks in advance for any help here if you have it! Best regards, - Jaymie
