Sentinel-2 SAFE conversion

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11-01-2016 02:51 AM
SanjayRana
New Contributor III

Hi Everyone,

I was wondering if anyone else has also experienced the issue that an ArcToolbox (copy raster function) conversion of Sentinel-2 .SAFE conversion to other formats automatically resamples all the bands to 60m. If so, did anyone find a solution?

Thanks,

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9 Replies
DanPatterson_Retired
MVP Emeritus

The product specs show the spatial resolution vs the number of bands at that resolution

Satellite sensor raster types—Help | ArcGIS for Desktop 

Sentinel-2 spacecraft has a Multi-Spectral Instrument (MSI) that collects data in spectral bands spanning from the visible and the near infrared to the shortwave infrared spectra at 3 different resolutions:

4 bands at 10m
6 bands at 20m
3 bands at 60m
Sentinel-2 MSI data is available as different product types and are systematically processed from Level-0 to Level-1C. Currently ArcGIS supports Level 1C products.

perhaps you only have the bands that are at 60m or you will have to resample those separately to get them associated with finer resolution bands.

SanjayRana
New Contributor III

Thanks Dan.  I do actually have all the bands. So, does the "copy raster" function works okay for you i.e. 10m S2 bands convert to 10 m and so on..

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DanPatterson_Retired
MVP Emeritus

Don't use them, but I would not expect another format to retain the differing cell sizes into one file type.  If you try exporting/copying the bands that are common (ie 10, 20, 60) separately, then I would expect the sizes to remain the same.  There is nothing in a tiff data structure, for example, to accommodate mixed cell sizes

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DanPatterson_Retired
MVP Emeritus

Also, check this blog to see if there is anything in there about the workflow that covers your situation

https://community.esri.com/community/gis/imagery-and-remote-sensing/blog/2016/04/27/use-sentinel-2-i... 

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CodyBenkelman
Esri Regular Contributor

Sanjay - no, the Copy Raster tool was not intended for datasets with multiple resolutions.  Can you tell us more about what you are seeking to do?  

Cody B.

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SanjayRana
New Contributor III

Cody, Dan - Many thanks for picking this up. I feel that SAFE format is still a bit unwieldy and uncommon format so basically would like to convert the files to common formats, particularly ERDAS Imagine, which does appear to have the ability to store multiband-rasters of various cell sizes, and would also keep (some of?)  the metadata. I have found that ArcMap is the only software that does the SAFE to IMAGINE conversion successfully and quickly i.e. not even ERDAS IMAGINE managed to do this well in my tests !

I thought the default cell size of 60m could be due to ArcMap's ENVIRONMENT settings for "cell size" in raster analysis, which are automatically defaulted to "maximum of inputs". I did trying setting the option of "minimum of inputs" but ArcMap crashed during the "copy raster". It would seem splitting the file into individual bands seems to be the only option.

I wouldn't mind if COPY RASTER resamples the 60m bands to 10m but to do the opposite is less desirable. I have also noticed that even for SAFE datasets, ArcMap although shows the 10m bands at a higher resolution than 60 m bands, the metadata or properties for the entire dataset still shows cell size of  60m. Perhaps a simple code-fix may be needed to read the xmls, differently for different bands and make the ENVIRONMENT setting option not crash the copy raster?

Thanks again!

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SanjayRana
New Contributor III

Hi, Before I do the band splitting, I was wondering if there are any workarounds at all?

Thanks,

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DanPatterson_Retired
MVP Emeritus

the resampling of the 60 to 20 or 10 is pretty well the only way you are going to get the data set into a useable format upon reassembly.  I presume that this should be a fairly clean process since each band would occupy the same space.  Given the uncommon format, you have the data for testing and would be best able to report back.  Whether you have to go to 20 or 10 would obviously depend on your band combinations and the outcomes and interpretations would undoubtedly be viewed in light of the coarser band even if resampled.  Aggregation to a coarser band is not the way to go.

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CodyBenkelman
Esri Regular Contributor

Sanjay

I will repeat my previous question.  Please tell us more about what you are seeking to do, with as much detail as possible.  

If you are intending to print the images to make a poster with Adobe Photoshop, our advice will be different than if you seek to create a mosaic and/or perform multispectral classification using ArcGIS.  How many scenes do you have?   Are you using ArcGIS do to the processing?  What version of ArcGIS do you have?  What are the dates of your Sentinel 2 scenes?

ESA has announced a new format for the imagery that will be coming out very soon, and I cannot confirm if we can support that format directly, but if you have images from October 2016 or earlier, and you are using ArcGIS 10.4, you can read the images DIRECTLY using the Mosaic Dataset and the Sentinel-2 raster type.  You will not resample the images in any band, you will not lose any resolution, and you will get the benefit of full metadata.  That is the purpose of the raster type.  We have published recommended workflows regarding the Mosaic Dataset in the Image Management Guidebook and you will find a workflow specific to Sentinel-2 at http://www.arcgis.com/home/item.html?id=e6e1f20cb0374d28a6eed24f5c2ff51b.  General information regarding the Mosaic Dataset is at  What is a mosaic dataset?—Help | ArcGIS for Desktop  

If you are going to resample your 60 meter bands to 10 meters, just realize you will increase the data volume for those bands by 36 times (28 MB will expand to 1 GB) and simultaneously reduce the quality of the imagery by resampling.  If you are seeking to use the imagery in Erdas Imagine, I would encourage you to look in their Help system or appropriate user forum.

Cody B

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