[gdal-dev] HDF5 and geolocation arrays
Even Rouault
even.rouault at spatialys.com
Mon Apr 29 13:08:48 PDT 2024
Michael,
actually support for those products was already there at 95% since they
use the HDF5EOS GRID formalism which we support since 3.7. But that
particular type of products has an oddity. They have an empty
GROUP=Dimension within the GROUP=GridStructure in the HDF5EOS metadata,
which our parser didn't like as we use the information in this group to
map dimension names to dimension index and size. Fixed/worked around in
https://github.com/OSGeo/gdal/pull/9807 . Hard to tell if those products
are in fault given that the HDF5EOS specification at
https://www.earthdata.nasa.gov/s3fs-public/imported/ESDS-RFC-008-v1.1.pdf
, appendix A, is extremely minimum regarding the HDF5EOS metadata itself
(for once, I complain for a spec to be too minimal !), and the example
they give for grids doesn't make sense to me (the declared dimension
names and sizes have nothing to do with the ones use in the grid)
I now get:
$ gdalinfo
HDF5:"AMSR_U2_L3_SeaIce12km_B04_20120702.he5"://HDFEOS/GRIDS/SpPolarGrid12km/Data_Fields/SI_12km_SH_18H_ASC
Driver: HDF5Image/HDF5 Dataset
Files: AMSR_U2_L3_SeaIce12km_B04_20120702.he5
Size is 632, 664
Coordinate System is:
PROJCRS["unnamed",
BASEGEOGCRS["Unknown datum based upon the custom spheroid",
DATUM["Not specified (based on custom spheroid)",
ELLIPSOID["Custom spheroid",6378273,0,
LENGTHUNIT["metre",1,
ID["EPSG",9001]]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]]],
CONVERSION["Polar Stereographic (variant B)",
METHOD["Polar Stereographic (variant B)",
ID["EPSG",9829]],
PARAMETER["Latitude of standard parallel",-70,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8832]],
PARAMETER["Longitude of origin",0,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8833]],
PARAMETER["False easting",0,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",0,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["(E)",north,
MERIDIAN[90,
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]],
ORDER[1],
LENGTHUNIT["Meter",1]],
AXIS["(N)",north,
MERIDIAN[0,
ANGLEUNIT["degree",0.0174532925199433,
ID["EPSG",9122]]],
ORDER[2],
LENGTHUNIT["Meter",1]]]
Data axis to CRS axis mapping: 1,2
Origin = (-3950000.000000000000000,4350000.000000000000000)
Pixel Size = (12500.000000000000000,-12500.000000000000000)
Metadata:
Conventions=CF-1.6
HDFEOS_INFORMATION_HDFEOSVersion=HDFEOS_5.1.15
history=This version of the Sea Ice processing code contains updates
provided by the science team on September 16, 2019. For details on these
updates, see the release notes provided in the DAP.
institution=NASA's AMSR Science Investigator-led Processing System (SIPS)
references=Please cite these data as: Markus, T., J. C. Comiso, and
W. N. Meier. 2018. AMSR-E/AMSR2 Unified L3 Daily 12.5 km Brightness
Temperatures, Sea Ice Concentration, Motion & Snow Depth Polar Grids,
Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA National
Snow and Ice Data Center Distributed Active Archive Center. doi:
https://doi.org/10.5067/RA1MIJOYPK3P.
source=satellite observation
title=AMSR-E/AMSR2 Unified L3 Daily 12.5 km Brightness Temperatures,
Sea Ice Concentration, Motion & Snow Depth Polar Grids
Corner Coordinates:
Upper Left (-3950000.000, 4350000.000) ( 42d14'27.21"W, 39d11'27.54"S)
Lower Left (-3950000.000,-3950000.000) (135d 0' 0.00"W, 41d23'59.41"S)
Upper Right ( 3950000.000, 4350000.000) ( 42d14'27.21"E, 39d11'27.54"S)
Lower Right ( 3950000.000,-3950000.000) (135d 0' 0.00"E, 41d23'59.41"S)
Center ( 0.000, 200000.000) ( 0d 0' 0.01"E, 88d 8'51.76"S)
Band 1 Block=632x1 Type=Int32, ColorInterp=Undefined
NoData Value=0
Metadata:
add_offset=0
coordinates=lon lat
long_name=18.7 GHz horizontal daily average ascending Tbs
packing_convention=netCDF
packing_convention_description=unpacked = scale_factor x packed +
add_offset
scale_factor=0.1
standard_name=brightness_temperature
units=degree_kelvin
_FillValue=0
Even
Le 29/04/2024 à 21:10, Michael Sumner via gdal-dev a écrit :
> This HDF5 (requires earthdata credentials your "Authorization: Bearer
> <token>" in GDAL_HTTP_HEADERS, or equiv) presents without geolocation
> arrays.
>
> gdalinfo
> "/vsicurl/https://n5eil01u.ecs.nsidc.org/AMSA/AU_SI12.001/2012.07.02/AMSR_U2_L3_SeaIce12km_B04_20120702.he5"
> -sd 26
> Driver: HDF5Image/HDF5 Dataset
> Files:
> /vsicurl/https://n5eil01u.ecs.nsidc.org/AMSA/AU_SI12.001/2012.07.02/AMSR_U2_L3_SeaIce12km_B04_20120702.he5
> Size is 608, 896
> Metadata:
> Conventions=CF-1.6
> HDFEOS_INFORMATION_HDFEOSVersion=HDFEOS_5.1.15
> history=This version of the Sea Ice processing code contains updates
> provided by the science team on September 16, 2019. For details on
> these updates, see the release notes provided in the DAP.
> institution=NASA's AMSR Science Investigator-led Processing System
> (SIPS)
> references=Please cite these data as: Markus, T., J. C. Comiso, and
> W. N. Meier. 2018. AMSR-E/AMSR2 Unified L3 Daily 12.5 km Brightness
> Temperatures, Sea Ice Concentration, Motion & Snow Depth Polar Grids,
> Version 1. [Indicate subset used]. Boulder, Colorado USA. NASA
> National Snow and Ice Data Center Distributed Active Archive Center.
> doi: https://doi.org/10.5067/RA1MIJOYPK3P.
> source=satellite observation
> title=AMSR-E/AMSR2 Unified L3 Daily 12.5 km Brightness Temperatures,
> Sea Ice Concentration, Motion & Snow Depth Polar Grids
> Corner Coordinates:
> Upper Left ( 0.0, 0.0)
> Lower Left ( 0.0, 896.0)
> Upper Right ( 608.0, 0.0)
> Lower Right ( 608.0, 896.0)
> Center ( 304.0, 448.0)
> Band 1 Block=608x1 Type=Int32, ColorInterp=Undefined
> Metadata:
> comment=data value meaning: 0 -- Open Water, 110 -- missing/not
> calculated, 120 -- Land
> coordinates=lon lat
> long_name=Sea ice concentration daily average
> units=percent
>
>
>
> gdalinfo --version
> GDAL 3.9.0dev-cb4d30f56d, released 2024/04/15
>
> The geolocation arrays are sds 33 and 32 respectively:
>
> HDF5:"/vsicurl/https://n5eil01u.ecs.nsidc.org/AMSA/AU_SI12.001/2012.07.02/AMSR_U2_L3_SeaIce12km_B04_20120702.he5"://HDFEOS/GRIDS/NpPolarGrid12km/lon
>
> HDF5:"/vsicurl/https://n5eil01u.ecs.nsidc.org/AMSA/AU_SI12.001/2012.07.02/AMSR_U2_L3_SeaIce12km_B04_20120702.he5"://HDFEOS/GRIDS/NpPolarGrid12km/lat
>
> And things work when lining those up in VRT with warp. Can the HDF5
> driver be made to auto-detect these geolocation arrays?
>
> I see that the NETCDF driver actually does:
>
> gdalinfo
> "NetCDF:/vsicurl/https://n5eil01u.ecs.nsidc.org/AMSA/AU_SI12.001/2012.07.02/AMSR_U2_L3_SeaIce12km_B04_20120702.he5"
> -sd 26
>
> I'm asking as an email rather than pursuing the fix because, these
> data are actually a regular grid on the north and south poles, and so
> geolocation by arrays is sub-optimal the specification is listed in
>
> https://nsidc.org/sites/default/files/au_si12-v001-userguide_1.pdf
>
> and the two parameter sets are
>
> Np-north: -te -3850000, -5350000, 3750000, 5850000 -t_srs EPSG:3411
> Sp-south: -te -3950000, -3950000, 3950000, 4350000 -t_srs EPSG:3412
>
> Is this generally something we should pursue within GDAL? It seems
> like an endless task to detect-on-open exactly this situation and
> assign the easy fix, but this is a pretty fundamental data stream and
> it's very common so the longlat/arrays might be numerically detectable
> with other heuristics hinting that it's polar (??) and there are
> plenty of other sources that present equivalents in the right way e.g.
> this one:
>
> "/vsicurl/https://noaadata.apps.nsidc.org/NOAA/G02135/north/daily/geotiff/2012/07_Jul/N_20120702_concentration_v3.0.tif"
>
> The right approach is probably to inform the providers and get the
> right metadata baked in ... but there's pros and cons to either. I'm
> not sure there's even enough information in these files to clearly
> detect the situation, it would be a bit like the NSIDCbin driver with
> its very strict requirements.
>
> Cheers, Mike
>
>
> --
>
> Michael Sumner
> Software and Database Engineer
> Australian Antarctic Division
> Hobart, Australia
> e-mail: mdsumner at gmail.com
>
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--
http://www.spatialys.com
My software is free, but my time generally not.
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