TopSAR Processing

[zahra0729]

Hi dear, I have a problem in step of coregistring of some topsar images…what’s the problem , I dont know!!pls help me!
Why I get into this problem, just in some images…!!? If my pc has a low memory RAM, why I could did interferometric analysis before this without any problems!!!

[ABraun]

java heap space indicates that your computer doesn’t have enough memory.

[zahra0729]

But why before this it worked well …i did around 50,60 interferogeram analysis by this pc!

[ABraun]

maybe other programs are consuming some RAM as well or your PC needs a restart…

[zahra0729]

My memory RAM is 8GB…
Thanks alot for your replying, but can i solve this problem by increasing my hard disk space?

[ABraun]

not really - unless your hard drive is 100% full, this would also cause errors.

Besides that, you can try to increase the cache:

Java Heap Space Error

Do you let the process run from the command line or directly within SNAP Desktop? In Desktop you can try to increase the cache. Go to Tools\Options and switch to the Performance tab. Set the Cache size to a higher value. e.g. 4096. You can also try to use the file cache. Therefor you need to change the option on the S1TBX tab. If you use gpt on the command line you can specify the -c parameter. Probably you also need to set the -q option. Maybe to something like 120. See

[zahra0729]

Thanks alot for the reply!
I perform analysis directely using snap desktop😒

[ABraun]

that means you can do what was suggested.

[zahra0729]

I increas cache up to 4026 … but it didn’t work!! Is it possible my images are not suitable for analysing???

[ABraun]

if you have more RAM you can of course enter a higher number.

[zahra0729]

I really dont know what can I do😞

[ABraun]

same reason

[zahra0729]

Maybe my images are not sutable!!

[ABraun]

How can I know? I don’t know your images or your PC environment? I can only guess from the very little information you provide. You didn’t even tell which sensor you are using.

[zahra0729]

I am using sentinel-1 images for analysing land subsidence in two regions of Iran, before this I was working on another region…and everything went well and without any error like this! But in this new region I just perform processing on 2 monthes data! After that I got into this problem,like java heap script or GC overhead and etc…

[ABraun]

did you reduce your data size in the TOPS coregistration menu?
It is described here: The Order of DEM Creating Steps

[zahra0729]

I didn’t reduce number of bursts before, but now how can I khonw how many number of burstes arr neccesary for me!I set the number between 4 to 6! and my intersted region locates on IW3…
Then Is it right in order to work on IW3 ,we select the number of bursts between 4to 6.???

[ABraun]

you can coarsely guess it a bit from the kmz file in the ‘preview’ folder

[zahra0729]

Thanks alot!!
I,ll try it​:pray:

[Serasia]

1. S1 TOPS coregistration with ESD2. Deburst and Subset3. Interferogram Formation4. Topographic Phase Removal5. Goldstein Phase Filtering6. Snaphu Exprort7. Unwrap via Snaphu8. Snaphu import9. Phase to Displacement10. Range - Doppler Terrain Correction11. Choose a reference point12. Final mapThis is a basic processing

Hi,
I have a very big problem.
I hve followed all the steps:

1. S1 TOPS coregistration with ESD
2. Deburst and Subset
3. Interferogram Formation
4. Topographic Phase Removal
5. Goldstein Phase Filtering
6. Snaphu Exprort
7. Unwrap via Snaphu
8. Snaphu import
9. Phase to Displacement
10. Range - Doppler Terrain Correction
11. Choose a reference point
12. Final map
    This is a basic processing

and I have also create the following band math:
final terrain corrected defo band * coherence mask band.

I have done this process in an area where I’m sure that there is a vertical displacement of -10m but my results are completely different.
How is it possible?
Where can I be wrong?

Please help me.
Thanks.