# HDF5 --- Hierarchical Data Format Release 5 (HDF5)

This driver intended for HDF5 file formats importing. This modification is suited for use with remote sensing data and fully compatible with underlying HDF5. This driver can import HDF5-EOS files. Currently EOS use HDF5 for data storing (telemetry form `Aura' satellites). In the future they will switch to HDF5 format, which will be used for telemetry from `Aura' satellite.

## Multiple Image Handling (Subdatasets)

Hierarchical Data Format is a container for several different datasets. For data storing. HDF contains multidimensional arrays filled by data. One HDF file may contain several arrays. They may differ in size, number of dimensions.

The first step is to get a report of the components images (arrays) in the file using gdalinfo, and then to import the desired images using gdal_translate. The gdalinfo utility lists all multidimensional subdatasets from the input HDF file. The name of individual images (subdatasets) are assigned to the SUBDATASET_n_NAME metadata item. The description for each image is found in the SUBDATASET_n_DESC metadata item. For HDF5 images the subdataset names will be formatted like this:

HDF5:file_name:subdataset

where:
file_name is the name of the input file, and
subdataset is the dataset name of the array to use (for internal use in GDAL).

On the second step you should provide this name for gdalinfo or gdal_translate for actual reading of the data.

For example, we want to read data from the OMI/Aura Ozone (O3) dataset:

    $ gdalinfo OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5
    Driver: HDF5/Hierarchical Data Format Release 5
    Size is 512, 512
    Coordinate System is `'

    Subdatasets:
      SUBDATASET_-1_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":APrioriLayerO3
      SUBDATASET_-1_DESC=[1645x60x11] APrioriLayerO3 (32-bit floating-point)
      SUBDATASET_0_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":AlgorithmFlags
      SUBDATASET_0_DESC=[1645x60] AlgorithmFlags (8-bit unsigned character)
      SUBDATASET_1_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":CloudFraction
      SUBDATASET_1_DESC=[1645x60] CloudFraction (32-bit floating-point)
      SUBDATASET_2_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":CloudTopPressure
      SUBDATASET_2_DESC=[1645x60] CloudTopPressure (32-bit floating-point)
      SUBDATASET_3_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":ColumnAmountO3
      SUBDATASET_3_DESC=[1645x60] ColumnAmountO3 (32-bit floating-point)
      SUBDATASET_4_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":LayerEfficiency
      SUBDATASET_4_DESC=[1645x60x11] LayerEfficiency (32-bit floating-point)
      SUBDATASET_5_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":NValue
      SUBDATASET_5_DESC=[1645x60x10] NValue (32-bit floating-point)
      SUBDATASET_6_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":O3BelowCloud
      SUBDATASET_6_DESC=[1645x60] O3BelowCloud (32-bit floating-point)
      SUBDATASET_7_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":QualityFlags
      SUBDATASET_7_DESC=[1645x60] QualityFlags (8-bit unsigned integer)
      SUBDATASET_8_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Reflectivity331
      SUBDATASET_8_DESC=[1645x60] Reflectivity331 (32-bit floating-point)
      SUBDATASET_9_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Reflectivity360
      SUBDATASET_9_DESC=[1645x60] Reflectivity360 (32-bit floating-point)
      SUBDATASET_10_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Residual
      SUBDATASET_10_DESC=[1645x60x10] Residual (32-bit floating-point)
      SUBDATASET_11_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":ResidualStep1
      SUBDATASET_11_DESC=[1645x60x10] ResidualStep1 (32-bit floating-point)
      SUBDATASET_12_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":ResidualStep2
      SUBDATASET_12_DESC=[1645x60x10] ResidualStep2 (32-bit floating-point)
      SUBDATASET_13_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":SO2index
      SUBDATASET_13_DESC=[1645x60] SO2index (32-bit floating-point)
      SUBDATASET_14_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Sensitivity
      SUBDATASET_14_DESC=[1645x60x10] Sensitivity (32-bit floating-point)
      SUBDATASET_15_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":StepOneO3
      SUBDATASET_15_DESC=[1645x60] StepOneO3 (32-bit floating-point)
      SUBDATASET_16_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":StepTwoO3
      SUBDATASET_16_DESC=[1645x60] StepTwoO3 (32-bit floating-point)
      SUBDATASET_17_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":TerrainPressure
      SUBDATASET_17_DESC=[1645x60] TerrainPressure (32-bit floating-point)
      SUBDATASET_18_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":UVAerosolIndex
      SUBDATASET_18_DESC=[1645x60] UVAerosolIndex (32-bit floating-point)
      SUBDATASET_19_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":dN_dR
      SUBDATASET_19_DESC=[1645x60x10] dN_dR (32-bit floating-point)
      SUBDATASET_20_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":dN_dT
      SUBDATASET_20_DESC=[1645x60x10] dN_dT (32-bit floating-point)
      SUBDATASET_21_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":GroundPixelQualityFlags
      SUBDATASET_21_DESC=[1645x60] GroundPixelQualityFlags (8-bit unsigned integer)
      SUBDATASET_22_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Latitude
      SUBDATASET_22_DESC=[1645x60] Latitude (32-bit floating-point)
      SUBDATASET_23_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":Longitude
      SUBDATASET_23_DESC=[1645x60] Longitude (32-bit floating-point)
      SUBDATASET_24_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":RelativeAzimuthAngle
      SUBDATASET_24_DESC=[1645x60] RelativeAzimuthAngle (32-bit floating-point)
      SUBDATASET_25_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":SolarAzimuthAngle
      SUBDATASET_25_DESC=[1645x60] SolarAzimuthAngle (32-bit floating-point)
      SUBDATASET_26_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":SolarZenithAngle
      SUBDATASET_26_DESC=[1645x60] SolarZenithAngle (32-bit floating-point)
      SUBDATASET_27_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":TerrainHeight
      SUBDATASET_27_DESC=[1645x60] TerrainHeight (8-bit integer)
      SUBDATASET_28_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":ViewingAzimuthAngle
      SUBDATASET_28_DESC=[1645x60] ViewingAzimuthAngle (32-bit floating-point)
      SUBDATASET_29_NAME=HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":ViewingZenithAngle
      SUBDATASET_29_DESC=[1645x60] ViewingZenithAngle (32-bit floating-point)
    Corner Coordinates:
    Upper Left  (    0.0,    0.0)
    Lower Left  (    0.0,  512.0)
    Upper Right (  512.0,    0.0)
    Lower Right (  512.0,  512.0)
    Center      (  256.0,  256.0)

Now select one of the subdatasets, described as `[1645x60] CloudFraction (32-bit floating-point)`:

    $ gdalinfo HDF5:"OMI-Aura_L2-OMTO3_2005m0326t2307-o03709_v002-2005m0428t201311.he5":CloudFraction
    Driver: HDF5Image/HDF5 Dataset
    Size is 60, 1645
    Coordinate System is:
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9108"]],
        AXIS["Lat",NORTH],
        AXIS["Long",EAST],
        AUTHORITY["EPSG","4326"]]
    GCP Projection = GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AXIS["Lat",NORTH],AXIS["Long",EAST],AUTHORITY["EPSG","4326"]]
    GCP[  0]: Id=, Info=
              (0.5,0.5) -> (261.575,-84.3495,0)
    GCP[  1]: Id=, Info=
              (2.5,0.5) -> (240.826,-85.9928,0)
    GCP[  2]: Id=, Info=
              (4.5,0.5) -> (216.754,-86.5932,0)
    GCP[  3]: Id=, Info=
              (6.5,0.5) -> (195.5,-86.5541,0)
    GCP[  4]: Id=, Info=
              (8.5,0.5) -> (180.265,-86.2009,0)
    GCP[  5]: Id=, Info=
              (10.5,0.5) -> (170.011,-85.7315,0)
    GCP[  6]: Id=, Info=
              (12.5,0.5) -> (162.987,-85.2337,0)
    ... 3000 GCPs are read from the file if Latitude and Longitude arrays are presents
    Corner Coordinates:
    Upper Left  (    0.0,    0.0)
    Lower Left  (    0.0, 1645.0)
    Upper Right (   60.0,    0.0)
    Lower Right (   60.0, 1645.0)
    Center      (   30.0,  822.5)
    Band 1 Block=60x1 Type=Float32, ColorInterp=Undefined
    Open GDAL Datasets:
      1 N DriverIsNULL 512x512x0

You may use gdal_translate for reading image bands from this dataset.

Note that you should provide exactly the contents of the line marked SUBDATASET_n_NAME to GDAL, including the HDF5: prefix.

This driver is intended only for importing remote sensing and geospatial datasets in form of raster images(2D or 3D arrays). If you want explore all data contained in HDF file you should use another tools (you can find information about different HDF tools using links at end of this page).

## Georeference

There is no universal way of storing georeferencing in HDF files. However, some product types have mechanisms for saving georeferencing, and some of these are supported by GDAL. Currently supported are (subdataset_type shown in parenthesis):

- HDF5 OMI/Aura Ozone (O3) Total Column 1-Orbit L2 Swath 13x24km (Level-2 OMTO3)

## Metadata

No Metadata are read at this time from the HDF5 files.

## Driver building

This driver builded on top of NCSA HDF5 library, so you need to dowload prebuild HDF5 librariesI HDF5-1.6.4 library or higher. You also need zlib 1.2 and szlib 2.0. For windows user be sure to set the attributes writable (especialy if you are using cygwin) and that the DLLs can be located somewhere by your PATH environment variable. You may also download source code NCSA HDF Home Page (see links below).

## See Also:

- Implemented as `gdal/frmts/hdf5/hdf5dataset.cpp` and `gdal/frmts/hdf5/hdf5imagedataset.cpp`.

- The NCSA HDF5 Dowload Page at the National Center for Supercomputing Applications
- The HDFView is a visual tool for browsing and editing NCSA HDF4 and HDF5 files.

  Documentation to individual products, supported by this driver:

  - Aura OMI Total Ozone Data Product-OMTO3