sentinel-2sentinel-snap
I see that others have problems similar to mine. Attempts to open Sentinel-2 data in SNAP by means of the *.xml file(s) fail.
When I pick the xml file from here, supposed to be metadata file,
the answer is: "No appropriate Product Reader found"
If I pick the xml file from the subdirectory “DATASTRIP/S2A_OPER_MSI_L1C_DS_SGS_…”, the answer is the same.
Is this due to error during downloading or dezipping? If so, how can this be avoided?
the RGB image in snap is built using the red, green and blue bands of Sentinel-2 MSI: respectively bands 4, 3, 2 (as you can see on the snap shot, those bands are selected by default). the "Profiles" in this case are predefined colour composites to visualize the data (only 3 out of the 13 spectral bands of Sentinel-2 can be sen by the human eye at once).
You can create a similar geotif with gdal by creating a stack of those three bands, located in the /GRANULE/yourimagename/IMG_DATA directory
gdalbuildvrt -separate output.vrt image_B04.jp2 image_B03.jp2 image_B02.jp2
gdal_translate output.vrt output.tif -co TILED=YES -co COMPRESS=LZW -co BIGTIFF=YES
The advantage of using SNAP is that you do not need to unzip the file archive in order to open the image, and it is easier to select a subset and mosaic.
For color stretching, the fastest way in SNAP is to use the color manipulation. By default it uses the statistics of the image, but on my example below there was a lot of clouds, so the colour stretching had to be adjusted (except if you are interested in clouds...). Note that this is on the fly manipulation, so the pixel values are not modified. You could also do this with command lines, but is is difficult to automate on raw data that have not been atmospherically corrected and cloud screened (cloud, cloud shadow, large water area... can strongly affect the statistics).
After unzipping, you should find an xml file inside the root directory with the same name as the zipped file. Select the xml file and be patient because opening the file takes a little while. You can then view the data per band, or right click on the scene name to open an RGB composite.
Normally this should also work directly from the zip file.
However, you should note that the zip files are sometimes corrupted during the download, which seems to be te case with your file. In other words, I think that you are doing the right things and that the software is OK, but that the error comes from the file.
Best Answer
Which version of SNAP are you using?
Which kind of METADATA (
*.xml) file have your scenes?From almost a year ago, metadata naming convention changed and old versions of SNAP don't support that kind of structure. The old version was named as
S2A_OPER_*.xml, now all scenes have the same metadata name:MTD_MSIL1C.xml(check product description file). In this threat, this topic is addressed.I recommend you to delete old version of SNAP after upgrading to the new one.