SNAPHU Software


#21

Thank you Dr Marcus Engdahl and Dr Andreas Braun for your comment.

There are 6 days data availabe in the same sensor S1A:
S1A_IW_GRDH_1SDV_20170107T231936_20170107T232005_014732_017FB3_85B8 and S1A_IW_GRDH_1SSV_20170113T115035_20170113T115100_014813_01821F_62DD

is it ok if I coregistrasion and make interferogram from these image (I will chose VV polarization). I doubt GRD mode can not produce any interferogram.

Thank you


#22

GRD only have amplitudes. You need complex data for interferometry. You need the SLC products.
https://sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/product-types-processing-levels/level-1


#23

Thank you for replay Dr Luis Veci

I got 5.52 day times differences but perpendicular baseline is -1169553 meter. Is it ok to proceed ?
S1A_IW_SLC__1SDV_20170107T231936_20170107T232006_014732_017FB3_2E70.zip (Master)
S1A_IW_SLC__1SSV_20170113T115034_20170113T115102_014813_01821F_5F0D.zip (Slave)


#24

unfortunately, I can not proceed SLC data because on 7 Jan 2017 1SDV, I need IW1 VV pol and on the image 13 Jan 2017 1SSV, I need need IW3 VV pol . It has different IW.

So no data for that particular area below 24 days for SLC.

I though Sentinel 1A and 1B should have 6 days data in that particular area.

Thank you for any comment


#25

right, you need products of same polarization. But not all areas are covered equally, as you see here:
https://sentinel.esa.int/web/sentinel/missions/sentinel-1/observation-scenario


#26

Thank you Dr Andrew Braun.

yes, same polarization but not same IW number can not proceed Dr Braun, is is right?

one more thing,
low coherence will affect interferogram. a lot of site in Indonesia, especially in Aceh Tengah, low coherence is presented due to high vegetation. It means I have to elliminate result of DinSAR and can not use Sentinel data to produce a good interferogram due to atmospheric disturbance.

I read some papers. It is low coherence present but at least unwrapping phase can be proceed to D-InSAR with other sensor such as ALOS.

Sorry out of topic, I should move to another topic, but don’t do where to put. just go through my question and answer :wink:

Thank you for comment


#27

every SLC product consists of 3 sub-swaths (IWs)
If your images are taken within the same track (which means they geographically align and have the same extents) there should be no technical problem using them for interferometry.
You can use the TOPSAR Split module to select only one of the three sub-swaths to decrease the file size.

About coherence: It is generally destroyed by vegetation cover. But if you use long wavelengths (ALOS PALSAR) you have higher chances to penetrate some of the smaller vegetation and get coherence from the surfaces. This however ends at high canopies.

Some more points to consider:



#28

Dear ABraun:
I am a new user of SNAP, according to the tutorial you given above, the smooth installation of cygwin and SNAPHU, but when I put the contents of the red box on the contents of the paste -ENTER, there is a problem shown on the picture,I did not get the desired result,and I do not know why, Hope to get your answer, thank you very much!


#29

somehow the file extension *.conf is not recognized by your command. Try renaming it to snaphu.conf and run again.


#30

When I was installing the cygwin , it says the following error. Could you help me solve this problem. Thanks.


#31

I’m not experienced with cygwin so unfortunately not. But you should try a server which is a bit closer to you than Esslingen in Germany :slight_smile:


#32

It’s my fault. There’s no enough space in C directory of my computer. Thanks.


#33

sir,
I tried snaphu phase unwrapping in ubuntu linux 14.04 LTS. My system is having 8 gb ram (dual boot). I got an error.

When i run the command - snaphu -f snaphu.conf Phase_ifg_HH_23Dec20­09_26Dec2010.snaphu.img 4672 it gives an error saying-
snaphu v1.4.2 27 parameters input from file snaphu.conf (84 lines total) only one tile–disregarding multiprocessor option Logging run-time parameters to file snaphu.log>

Segmentation fault (core dumped)

Please guide me through this.I am not using cygwin terminal.
Thanks


#34

I rename file to: snaphu.conf but still can not work

your help is appreciated

thank you


#35

Could you please help me to find S1A_IW_SLC__1SSV data. In scihub.copernicus.eu I can ony find S1A_IW_SLC__1SDV images,

Thanks a lot,


#36

SSV is single polarization, so only VV band is included
SDV is dual polarization, both VV and VH bands are included.

For interferometry you only need one band (usually VV), so it doesn’t matter which products you use.