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Tools and Examples that Improve the
Interoperability of NASA HDF-EOS Data
http://hdfeos.org
MuQun Yang, Hyo-Kyung Lee, and Mike Folk
The HDF Group
The HDF Group has developed and maintained the following tools for the interoperability of NASA HDF and HDF-EOS data. Some tools are still under active development.
Use netCDF tools to access HDF-EOS via OPeNDAP
Users
Terra/Aqua/Aura
Translation Layers
HDF4/5
Handlers
libnc-dap
DAP
netCDF Visualization
Tools
OPeNDAP
Clients
OPeNDAP
Servers
HDF4/5 Files
Use NetCDF-4 to access HDF-EOS5
Augmentation
HDF-EOS5
NetCDF4
HDF-EOS5
file
HDF5
Augmented
HDF-EOS5
file
NetCDF-4
file
HDF5
Use HDF-EOS2 Dumper to help the access of HDF-EOS2 using IDL and MATLAB
Example Usage: %eos2dump –a1m MYD02HKM.A2010031.0035.005.2010031183706.hdf
Use cases: HDF-EOS2 files
with non-geographic
projections, like SINSOID
and SOM, and swath
dimension maps.
Latitude
Longitude
in ASCII file
HDF-EOS2 Dumper
Extract geo-location
information
HDF-EOS2 File
HDF SDS Interface
MATLAB
IDL
Example Latitude Output:
-61.0802, -61.0949, -61.1096,
-61.1241, -61.1387, -61.1531,
-61.1675, -61.1818,-61.196,
…
Text file Interface
Use HDF4 XML Map Writer to access HDF4 using generic file readers
hmap
linked with
HDF4 library
HDF4 File
Object Data
Reader
program
HDF4 Mapping File
(XML document)
Groups, Data Objects,
Structural and Application
Metadata;
Locations of Object Data
This work was supported by cooperative agreement number NNX08AO77A from the National Aeronautics and Space Administration (NASA).
Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author[s] and do not necessarily reflect
the views of the National Aeronautics and Space Administration.
http://hdfeos.org
OPeNDAP Examples
GES DISC AIRS IDV
NSIDC AMSR_E IDV
NSIDC AMSR_E Panoply
GES DISC OMI IDV
LP DAAC MODIS IDV
LAADS MODIS Panoply
LaRC MISR Panoply
GES DISC MLS Panoply
HDF-EOS5 Augmentation Tool Example
HDFEOS
GRIDS
CloudFractionAndPressure
Data Fields
CloudFraction[XDim][YDim]
Products supported:
NASA Aura HIRDLS,
MLS, OMI, TES, and
MEaSUREs GSSAP
[nLevels][nTimes]
CloudPressure[XDim][YDim]
XDim
YDim
Provide coordinates
required by netCDF-4.
Provide the connections between
dimension and dimension scales.
MATLAB and IDL examples that use the HDF-EOS2 Dumper outputs
LAADS MODIS Aqua IDL
(Swath)
LP DAAC MODIS Terra MATLAB
(Grid)
HDF4 XML Map Writer Example
/* Open the hdf file for reading. */
infile = fopen(hdfname, "rb");
if(infile == NULL) {
printf("Error opening file: %s\n", hdfname);
exit(EXIT_FAILURE);
}
/* Read the dataset into the buffer. */
buffer = malloc(nBytes);
fseek(infile, offset, 0);
fread(buffer, 1, nBytes, infile);
Provide offset and bytes
of HDF4 objects in XML.
Read binary data
with fseek() and fread() in C.
NSIDC AMSR_E IDL
(Polar Grid)
def __init__(self,hdf_fileName):
try: #it opens the HDF creating a file object
file_path=path.normpath(hdf_fileName)
self.file_handler=file(file_path,"rb")
…
self.file_handler.seek(int(chunk.attrib["offset"]),0)
#if chunk.attrib["compression"] in
("zlib","szip","DEFLATE"):
tmp_buffer_object.write(self.file_handler.read(int(chun
k.attrib["nBytes"])))
Read binary data
with seek() and read() in Python.
Acknowledgements: We thank Dan Marinelli, Carol Boquist and Rama Ramapriyan of the NASA ESDIS project; Christopher Lynnes, James
Johnson and Fan Fang from NASA GES DISC; Ruth Duerr from NSIDC; James Gallagher from OPeNDAP, Inc.; Cheryl Craig from HIRDLS team;
UCAR's NCL User Group and John Evans from MathWorks for their valuable suggestions and help.