What is step processing to do same as romania mosaic?

snap
#1

Hello,

I would like to to similar rhings as romania mosaic at this link.
https://sentinel.esa.int/web/sentinel/missions/sentinel-1/news/-/article/sentinel-1-mosaic-of-romania

It’s amaazing tho homogeneaity of radiometry at this scale so I supposed that that there is radiometric correction using dem.

So I think that the main step is first calibration with gamma naught in order to apply terrain correctionwith radiometric correction using local incidence angle.

So I would like to know if it’s really this step and in addition how many time it takes to process that mosaic for what kind of computer ?

Indeed I would like to do same thing on guiana shiekd with approxymatively 15 Iww desending and 4 ascending.

Thanks in advance.

#2

As soon as the next update is released there will be a new operator to remove the garbage on the borders of GRD images.
Apply GRD border noise removal, calibration to beta0, multilooking, terrain flattening, terrain correction.

#3

Hello,

Thanks a lot for information and I am really impatient to try new version in order to build graph including processing that you explain with also bandmath that does not work well with snap beta 2.05 due to interface bug.

#4

Iveci,
Has ESA documented how those borders can be masked out?

thanks

#5

Ah, Luis, so you are now convinced that you can do multi-looking BEFORE terrain flattening??
That’s good to know, because it makes for a faster processing chain.

Guido

#6

For grd product you multilook at 20x20 i supposed ?

I have tried a graph with all the step shown before and on my laptot in xubuntu with 8go ram Unfortunately I have an error java vm heap… At terrain flatening step.
However, graph with cal and terrain correction works well.

I know that it’s due memory issue because it works well in a subset.

Have you an idea to solve this memory problem ?

edit: same with 2. beta 06. Is it necessary to use a stronger computer with at least 16GO of ram or is it possible to use standard laptop (4GO) with some tricks ?

Thanks in advance

#7

clardeux, 4GB is definitely not recommended, 8GB is the minimum in my opinion and 16GB the “recommended” amount. You should upgrade your memory, I have 64Gb on my workstation and I’ve seen the snap64-process grab up to 20Gb so far.

#8

I agrreebwith you that for now ot’s better to have more ram to work and work faster with snap.

However and Unfortunately everybody don’t have workstation like asn I see in my project.

This is why, if it’s possible to find a way to optimize memory management or memory settings in snap for people who have not workstation would be very nice.

Thanks for reply