S2 SAFE files output no geospatial info

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srego
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Joined: Thu Jul 01, 2021 4:00 pm
company / institution: US. Environmental Protection Agency
Location: Rhode Island, USA

S2 SAFE files output no geospatial info

Post by srego »

Greetings - Im new to polymer and am trying to process some Sentinel 2 SAFE files through the application. The SAFE files have a projection prior to processing of WGS 84 / UTM ZONE 18 (EPSG 32618). The polymer output appears to be in width, height. Should I assume those are in Meters? Im seeing lat/lon variables as well. Does this output look correct from ncdump?

Portion of ncdump output file
netcdf test {
dimensions:
width = 10980 ;
height = 10980 ;
variables:
double latitude(height, width) ;
latitude:_FillValue = 9.96920996838687e+36 ;
double longitude(height, width) ;
longitude:_FillValue = 9.96920996838687e+36 ;
short bitmask(height, width) ;
bitmask:_FillValue = -32767s ;
bitmask:description = "LAND:1, CLOUD_BASE:2, L1_INVALID:4, NEGATIVE_BB:8, OUT_OF_BOUNDS:16, EXCEPTION:32, THICK_AEROSOL:64, HIGH_AIR_MASS:128, EXTERNAL_MASK:512, CASE2:1024, INCONSISTENCY:2048, ANOMALY_RWMOD_BLUE:4096" ;
bitmask:bitmask_reject = "bitmask & 1023 != 0" ;
float Rnir(height, width) ;
Rnir:_FillValue = 9.96921e+36f ;

Thanks
Steve
sakvaka_env
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Location: Helsinki, Finland

Re: S2 SAFE files output no geospatial info

Post by sakvaka_env »

As far as I know, the output has the same reference grid as the input (possibly resampled). The lat/lon bands are filled in by Polymer and are based on retrieving the UTM grid coordinates from the scene metadata and transforming those into longitudes and latitudes.
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fsteinmetz
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Re: S2 SAFE files output no geospatial info

Post by fsteinmetz »

This is correct. The level2 output is provided in the same gris as the level1. For Sentinel-2, there is an option for using the level1 at either 10, 20 or 60 m of spatial resolution, other than this over or undersampling, there is no reprojection in Polymer.
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