Sentinel 2 mosaic


#1

Hi,

I am trying to mosaic together two Sentinel 2 images, but when I try to run the mosaic it says that “Product ‘sourceProduct2’ contains bands of different sizes. Currently it is not possible to use it for mosaicking”

Both images correspond to the same path/taken the same day so they should have the same number and configuration of bands. I have tried also to mosaic only two of contiguous granules (lower right corner granule for the northern image and upper right corner for the southern image) but I get the same error.

I assume I have to do something with them before, but what? All granules and complete images have been saved in Beam-dimap format.


Remember decision by opening product
#2

Probably you have opened the Sentinel 2 products in their native resolution. It is better to chose one of the three offered resolutions when you try to open an S2 product. Either 10, 20 or 60 meter resolution. Probably you want the 10m resolution.


#3

Hello Marpet,

Do you mean open bands of the same resolutions only and leave the other ones out? Can you please advise on how to open all 13 of the sentinel products in just one resolution size?


#4

If you open the 10 m bands from the .xml file the other bands remain. However, I get still the same error when I attempt to mosaic.
The image shows the word view for when the native resolution is open (left) and the 10 m resol is open (right), just in cas it is of any help.


#5

What I ment that you have to choose the 10m resolution when opening the product. See image:
These products can be saved to BEAM-DIMAP format and then used for the mosaic.
This is still a bit inconvenient because we haven’t fully solved the multi-resolution issue.


#6

That’s what I did, but it still says that the band sizes are different :frowning:

Additionally, what I exaclty would need is to mosaic the granules 1 and 2 (see right side of the image attached), since it covers my study area. Problem is that one is in zone 36 south and the other one in zone 37 south. If I open both in the same zone (either 36 or 37) I end up losing part of my study area.

Anyways, whether I open both in the same or different zones I get the “Product ‘sourceProduct2’ contains bands of different sizes. Currently it is not possible to use it for mosaicking”

What to do what to do…


#7

I managed to do it in ERDAS subsetting the 10 m bands, process that took 6 hours for two granules…

If I now do it in SNAP it doesn’t give me any error message, but the resolution gets resampled to 60 m wheather I choose the 10 m or the 20 m bands.

May I assume then that SNAP is not ready for mosaicking S2 images yet?


#8

I managed to do decent mosaics with all the bands using the Semiautomatic classification plug-in in QGIS. It works very nicely! And there are useful tutorials too.


#9

Dear Javier,

Please be informed that, recently, we have uploaded a video tutorial on how to perform a mosaic using S2 data at: http://step.esa.int/main/doc/tutorials/snap-tutorials

The direct YouTube link is:
https://www.youtube.com/watch?v=PTmLs9BRSKE

Best regards


#10

Hi!

I have the same problem by making mosaics . SNAP gives me an error message : the bands do not have the same size .
I tried semi auto- classification with Qgis but it really takes a lot of time.
Is there a solution to have Bands of the same size?
Thank you


#11

Thanks Fabrizio! However, despite all the process runs fine and takes it time (a lot of time) I get an empty output when trying to get a 10 or 20 m resolution mosaic of two granules.

EDIT: All right, it seems that the image I was working with was somehow corrupted. I tried it with another pair of granules and it worked, and very fast!


#12

java.lang.NullPointerException
at org.esa.s2tbx.dataio.s2.ortho.Sentinel2OrthoProductReader.getMosaicProduct(Sentinel2OrthoProductReader.java:183)
at org.esa.s2tbx.dataio.s2.Sentinel2ProductReader.readProductNodesImpl(Sentinel2ProductReader.java:126)
at org.esa.snap.core.dataio.AbstractProductReader.readProductNodes(AbstractProductReader.java:169)
at org.esa.snap.core.dataio.ProductIO.readProduct(ProductIO.java:158)
at org.esa.snap.rcp.actions.file.ReadProductOperation.run(ReadProductOperation.java:37)
at org.netbeans.modules.progress.ui.RunOffEDTImpl$3.run(RunOffEDTImpl.java:275)
at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
[catch] at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)

When i tried to open the Granule in 10 meter resolution I got this message. What can i do to solve this?


#13

I am having problems to mosaic images in SNAP 3 (never had them in SNAP 2). The mosaic tool cannot read the part of the image which is in zone 36, only the one in zone 37 and I have no idea hot to change it. In the screencap you can see the extension of the images in the world view for zone 36, but when I check the box “display source products” in the mosaicing tool, it only displays the part corresponding to zone 37. Any idea how to modify this?


#14

Hi Javier,
Do you still have the same problem? Was it fixed since then?
Is it also the case with version 4.0?
Please let us know, I inform Julien, Nicolas and Omar about this behaviour, but they surely are already.
Thanks a lot for these elements of observation.
Cheers
Olivier


#15

Hi Olivier,

There are still problems with the mosaic tool (and re-projection too).
When trying to select a pre-defined CRS (ESPG:2193), you can find it OK but it is not put into the white space.

Cheers,
Mike


#16

Hello,
Now that the products are in several files, they need to be combined…
I’m trying to mosaic resampled products in .dim files and data folders. I’m curious about the pixel size - how come the default is not the pixel size of the resampled product? The fill in box in the GUI is in degrees and the smallest it accepts if 0.001. My mosaic is very coarse at best and at default value I get huge pixels. Question is: how to get 10m pixels when mosaicing BEAM-DIMAP products that are resampled to 10m?

-Paula


#17

In the Mosaic is WGS_84 as default projection selected. Its CRS is defined in degree. That’s why the pixel size is given in degree by default.
What’s wrong here is that you can’t define a small pixel size correctly. Below 0.001 it only shows 0.0. But it uses the values you have entered. So it is only a display issue. However this is wrong.

If you change in the upper part the projection, e.g. to UTM, you can enter the pixel size in meter.


#18

Thanks!

It went well untill I clicked run and got an error message about my cloud and cloud shadow condition, when I tried to remove the condition the whole mosaic app froze and I could not select anything. I restarted SNAP and started new mosaic, but the tabs Map Project Definition and Variables & Conditions remained frozen. Maybe I need to restart unity? Or reboot?

Fix: It seems I did not select the source, it was not enough to + it, I needed to select it also… now it seems to work :sweat_smile:

-Paula


#19

OK, good that it works now.


#20

Well. It wrote a 104 GB mosaic from two granules in 1h 43 min. The mosaic looks universally grey in SNAP. It seems that something went wrong.

-Paula