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The HDF Group
Introduction to HDF5
Barbara Jones
The HDF Group
The 13th HDF & HDF-EOS Workshop
November 3-5, 2009
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 1 www.hdfgroup.org
Before We Begin …
HDF-EOS Home Page: http://hdfeos.org/
Workshop Info:
http://hdfeos.org/workshops/ws13/workshop_thirteen.php
The HDF Group Page: http://hdfgroup.org/
HDF5 Home Page: http://hdfgroup.org/HDF5/
HDF Helpdesk: help@hdfgroup.org
HDF Mailing Lists: http://hdfgroup.org/services/support.html
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 2 www.hdfgroup.org
HDF = Hierarchical Data Format
HDF5 is the second HDF format
• Development started in 1996
• First release was in 1998
HDF4 is the first HDF format
• Originally called HDF
• Development started in 1987
• Still supported by The HDF Group
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 3 www.hdfgroup.org
HDF5 is like…
5
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 4 www.hdfgroup.org
HDF5 is designed …
• for high volume and/or complex data
• for every size and type of system (portable)
• for flexible, efficient storage and I/O
• to enable applications to evolve in their use of
HDF5 and to accommodate new models
• to support long-term data preservation
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 5 www.hdfgroup.org
HDF5 Technology
HDF5 is a data model, library and file format for
managing data.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 6 www.hdfgroup.org
HDF5 Technology
• HDF5 (Abstract) Data Model
• Defines the “building blocks” for data organization and
specification
• Files, Groups, Datasets, Attributes, Datatypes, Dataspaces, …
• HDF5 Library (C, Fortran 90, C++ APIs)
• Also Java Language Interface and High Level Libraries
• HDF5 Binary File Format
• Bit-level organization of HDF5 file
• Defined by HDF5 File Format Specification
• Tools For Accessing Data in HDF5 Format
• h5dump, h5repack, HDFView, …
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 7 www.hdfgroup.org
The HDF Group
HDF5 Abstract Data Model
a.k.a. HDF5 Logical Data Model
a.k.a. HDF5 Data Model
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 8 www.hdfgroup.org
HDF5 File
lat | lon | temp
----|-----|-----
12 | 23 | 3.1
An HDF5 file is a 15 | 24 | 4.2
17 | 21 | 3.6
container that
holds data
objects.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 9 www.hdfgroup.org
HDF5 Groups and Links
HDF5 groups
and links Experiment Notes:
Serial Number: 99378920
/
organize
Date: 3/13/09
Configuration: Standard 3
data objects.
Viz SimOut
lat | lon | temp
----|-----|-----
12 | 23 | 3.1
15 | 24 | 4.2
17 | 21 | 3.6
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 10 www.hdfgroup.org
HDF5 Objects
The two primary HDF5 objects are:
• HDF5 Group: A grouping structure containing
zero or more HDF5 objects
• HDF5 Dataset: Raw data elements, together
with information that describes them
(There are other HDF5 objects that help support
Groups and Datasets.)
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 11 www.hdfgroup.org
HDF5 Groups
• Used to organize collections
• Every file starts with a root group
“/”
• Similar to UNIX directories A C
• Path to object defines it B
• Objects can be shared:
/A/k and /B/l are the same temp k l
temp
= Group
= Dataset
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 12 www.hdfgroup.org
HDF5 Datasets
HDF5 Datasets organize and contain your
“raw data values”. They consist of:
• Your raw data
• Metadata describing the data:
- The information to interpret the data (Datatype)
- The information to describe the logical layout of the
data elements (Dataspace)
- Characteristics of the data (Properties)
- Additional optional information that describes the
data (Attributes)
November 3-5,
2009 HDF/HDF-EOS Workshop XIII 13 www.hdfgroup.org
HDF5 Dataset
Metadata Data
Dataspace
Rank Dimensions
3 Dim_1 = 4
Dim_2 = 5
Dim_3 = 7
Datatype
Integer (optional)
Attributes
Properties Time = 32.4
Chunked Pressure = 987
Compressed Temp = 56
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 14 www.hdfgroup.org
HDF5 Dataspaces
An HDF5 Dataspace describes the logical layout
for the data elements:
• Array
• multiple elements in dataset organized in a
multi-dimensional (rectangular) array
• maximum number of elements in each
dimension may be fixed or unlimited
• NULL
• no elements in dataset
• Scalar
• single element in dataset
•
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 15 www.hdfgroup.org
HDF5 Dataspaces
Two roles:
Dataspace contains spatial information (logical
layout) about a dataset
stored in a file
• Rank and dimensions
• Permanent part of dataset
definition Rank = 2
Dimensions = 4x6
Partial I/0: Dataspace describes application’s data
buffer and data elements participating in I/O
Rank = 1
Dimension = 10
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 16 www.hdfgroup.org
HDF5 Datatypes
The HDF5 datatype describes how to interpret
individual data elements.
HDF5 datatypes include:
− integer, float, unsigned, bitfield, …
− user-definable (e.g., 13-bit integer)
− variable length types (e.g., strings)
− references to objects/dataset regions
− enumerations - names mapped to integers
− opaque
− compound (similar to C structs)
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 17 www.hdfgroup.org
HDF5 Dataset
3
5
V
Datatype: 16-byte integer
Dataspace: Rank = 2
Dimensions = 5 x 3
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 19 www.hdfgroup.org
HDF5 Properties
• Properties (also known as Property Lists)
are characteristics of HDF5 objects that can
be modified
• Default properties handle most needs
• By changing properties one can take
advantage of the more powerful features in
HDF5
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 20 www.hdfgroup.org
Storage Properties
Data elements
Contiguous stored physically
adjacent to each
(default) other
Better access time
Chunked for subsets;
extensible
Improves storage
Chunked & efficiency,
Compressed transmission speed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 21 www.hdfgroup.org
HDF5 Attributes (optional)
• An HDF5 attribute has a name and a value
• Attributes typically contain user metadata
• Attributes may be associated with
- HDF5 groups
- HDF5 datasets
- HDF5 named datatypes
• An attribute’s value is described by a datatype and a
dataspace
• Attributes are analogous to datasets except…
- they are NOT extensible
- they do NOT support compression or partial I/O
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 22 www.hdfgroup.org
HDF5 Abstract Data Model Summary
• The Objects in the Data Model are the “building
blocks” for data organization and specification
• Files, Groups, Links, Datasets, Datatypes,
Dataspaces, Attributes, …
• Projects using HDF5 “map” their data concepts to
these HDF5 Objects
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 23 www.hdfgroup.org
The HDF Group
HDF5 Software
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 24 www.hdfgroup.org
HDF5 Software Layers & Storage
API
Tools
h5dump h5repack HDFview
… High Level
tool tool tool
APIs
Java Interface
Language HDF5 Data Model
Interfaces Tunable Properties
Objects Chunk Size, I/O Driver, …
C, Fortran, C++ Groups, Datasets, Attributes, …
HDF5 Library
Memory Datatype Chunked Version and so
Internals Mgmt Conversion
Filters
Storage Compatibility on…
Virtual File
Posix Split
Layer MPI I/O Custom
I/O Files
I/O Drivers
Storage
HDF5 File File on
Format File Split
Parallel Other
Files
Filesystem
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 25 www.hdfgroup.org
HDF5 API and Applications
aClimate MATLAB
Applications Model
Domain Data EOS …
Objects library
HDF5 Library
Storage
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 26 www.hdfgroup.org
HDF5 Home Page
HDF5 home page: http://hdfgroup.org/HDF5/
• Two releases: HDF5 1.8 and HDF5 1.6
HDF5 source code:
• Written in C, and includes optional C++, Fortran 90 APIs,
and High Level APIs
• Contains command-line utilities (h5dump, h5repack,
h5diff, ..) and compile scripts
HDF pre-built binaries:
• When possible, include C, C++, F90, and High Level
libraries. Check ./lib/libhdf5.settings file.
• Built with and require the SZIP and ZLIB external
libraries
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 27 www.hdfgroup.org
Useful Tools For New Users
h5dump:
Tool to “dump” or display contents of HDF5 files
h5cc, h5c++, h5fc:
Scripts to compile applications
HDFView:
Java browser to view HDF4 and HDF5 files
http://www.hdfgroup.org/hdf-java-html/hdfview/
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 28 www.hdfgroup.org
h5dump Utility
h5dump [options] [file]
-H, --header Display header only – no data
-d <names> Display the specified dataset(s).
-g <names> Display the specified group(s) and
all members.
-p Display properties.
<names> is one or more appropriate object names.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 29 www.hdfgroup.org
Example of h5dump Output
HDF5 "dset.h5" {
GROUP "/" {
DATASET "dset" {
DATATYPE { H5T_STD_I32BE }
DATASPACE { SIMPLE ( 4, 6 ) / ( 4, 6 ) }
DATA {
1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24
} “/”
} ‘dset’
}
}
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 30 www.hdfgroup.org
HDF5 Compile Scripts
• h5cc – HDF5 C compiler command
• h5fc – HDF5 F90 compiler command
• h5c++ – HDF5 C++ compiler command
To compile:
% h5cc h5prog.c
% h5fc h5prog.f90
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 31 www.hdfgroup.org
Compile option: -show
-show: displays the compiler commands and options
without executing them
% h5cc –show Sample_c.c
Will show the correct paths and libraries used by
the installed HDF5 library.
Will show the correct flags to specify when
building an application with that HDF5 library.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 32 www.hdfgroup.org
The HDF Group
Browsing HDF5 Files with
HDFView
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 33 www.hdfgroup.org
HDFView
Structure of File Contents
of Dataset
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 34 www.hdfgroup.org
HDFView File Menu
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 35 www.hdfgroup.org
HDF-EOS5 File in HDFView
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 36 www.hdfgroup.org
Introduction to
HDF5 Programming Model
and APIs
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 37 www.hdfgroup.org
Operations Supported by the API
• Create objects (groups, datasets, attributes, complex data
types, …)
• Assign storage and I/O properties to objects
• Perform complex subsetting during read/write
• Use variety of I/O “devices” (parallel, remote, etc.)
• Transform data during I/O
• Make inquiries on file and object structure, content,
properties
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 38 www.hdfgroup.org
General Programming Paradigm
• Properties of object are optionally defined
Creation properties
Access properties
• Object is opened or created
• Object is accessed, possibly many times
• Object is closed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 39 www.hdfgroup.org
Order of Operations
• An order is imposed on operations by
argument dependencies
For Example:
A file must be opened before a dataset
-because-
the dataset open call requires a file handle
as an argument.
• Objects can be closed in any order.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 40 www.hdfgroup.org
The General HDF5 API
• Currently C, Fortran 90, Java, and C++
bindings.
• C routines begin with prefix H5?
? is a character corresponding to the type of
object the function acts on
Example Functions:
H5D : Dataset interface e.g., H5Dread
H5F : File interface e.g., H5Fopen
H5S : dataSpace interface e.g., H5Sclose
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 41 www.hdfgroup.org
HDF5 Defined Types
For portability, the HDF5 library has its own defined
types:
hid_t: object identifiers (native integer)
hsize_t: size used for dimensions (unsigned long or
unsigned long long)
herr_t: function return value
hvl_t: variable length datatype
For C, include hdf5.h in your HDF5 application.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 42 www.hdfgroup.org
The HDF5 API
• For flexibility, the API is extensive Victronix
Swiss Army
300+ functions
Cybertool
34
• This can be daunting… but there is hope
A few functions can do a lot
Start simple
Build up knowledge as more features are
needed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 43 www.hdfgroup.org
Basic Functions
H5Fcreate (H5Fopen) create (open) File
H5Screate_simple/H5Screate create dataSpace
H5Dcreate (H5Dopen) create (open) Dataset
H5Dread, H5Dwrite access Dataset
H5Dclose close Dataset
H5Sclose close dataSpace
H5Fclose close File
NOTE: The order specified above is not required.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 44 www.hdfgroup.org
Other Common Functions
DataSpaces: H5Sselect_hyperslab (Partial I/O)
H5Sselect_elements (Partial I/O)
H5Dget_space
Groups: H5Gcreate, H5Gopen, H5Gclose
Attributes: H5Acreate, H5Aopen_name,
H5Aclose, H5Aread, H5Awrite
Property lists: H5Pcreate, H5Pclose
H5Pset_chunk, H5Pset_deflate
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 45 www.hdfgroup.org
High Level APIs
• Included along with the HDF5 library
• Simplify steps for creating, writing, and
reading objects.
• Do not entirely ‘wrap’ HDF5 library
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 46 www.hdfgroup.org
The HDF Group
Example HDF5 Code
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 47 www.hdfgroup.org
Steps to Create a File
1. Decide on properties the file should have and
create them if necessary:
• Creation properties, like size of user block
• Access properties (improve performance)
• Use default properties (H5P_DEFAULT)
2. Create the file
3. Close the file and the property lists, as needed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 48 www.hdfgroup.org
Code: Create a File
hid_t file_id;
herr_t status;
file_id = H5Fcreate("file.h5", H5F_ACC_TRUNC,
H5P_DEFAULT, H5P_DEFAULT);
status = H5Fclose (file_id);
“/” (root)
Note: Return codes not checked for errors in code samples.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 49 www.hdfgroup.org
Dataset Components
Metadata Data
Dataspace
Rank Dimensions
3 Dim_1 = 4
Dim_2 = 5
Dim_3 = 7
Datatype
Integer
Properties
Chunked
Compressed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 50 www.hdfgroup.org
Steps to Create a Dataset
1. Define dataset characteristics
a) Datatype – integer
b) Dataspace - 4x6
c) Properties if needed, or use H5P_DEFAULT
2. Decide where to put it
• Obtain location ID: “/” (root)
A
- Group ID puts it in a Group
- File ID puts it in Root Group
3. Create dataset in file
4. Close everything
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 51 www.hdfgroup.org
HDF5 Pre-defined Datatype Identifiers
HDF5 defines* set of Datatype Identifiers per HDF5
session.
For example:
C Type HDF5 File Type HDF5 Memory Type
int H5T_STD_I32BE H5T_NATIVE_INT
H5T_STD_I32LE
float H5T_IEEE_F32BE H5T_NATIVE_FLOAT
H5T_IEEE_F32LE
double H5T_IEEE_F64BE H5T_NATIVE_DOUBLE
H5T_IEEE_F64LE
* Value of datatype is NOT fixed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 52 www.hdfgroup.org
Pre-defined File Datatype Identifiers
Examples:
H5T_IEEE_F64LE Eight-byte, little-endian, IEEE floating-point
H5T_STD_I32LE Four-byte, little-endian, signed two's
complement integer
Programming
Architecture* Type
NOTE: What you see in the file. Name is the same everywhere and
explicitly defines a datatype.
*STD= “An architecture with a semi-standard type like 2’s complement integer, unsigned integer…”
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 53 www.hdfgroup.org
Pre-defined Native Datatypes
Examples of predefined native types in C:
H5T_NATIVE_INT (int)
H5T_NATIVE_FLOAT (float )
H5T_NATIVE_UINT (unsigned int)
H5T_NATIVE_LONG (long )
H5T_NATIVE_CHAR (char )
NOTE: Memory types.
Different for each machine.
Used for reading/writing.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 54 www.hdfgroup.org
Storage Properties
Data elements
stored physically
Contiguous adjacent to each
(default) other
Better access time
Chunked for subsets;
extensible
Improves storage
Chunked &
efficiency,
Compressed transmission speed
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 55 www.hdfgroup.org
Code: Create a Dataset
1 hid_t file_id, dataset_id, dataspace_id;
2 hsize_t dims[2];
. herr_t status;
.
. Define H5F_ACC_TRUNC,
file_id = H5Fcreate (”file.h5", a dataspace
. H5P_DEFAULT, H5P_DEFAULT);
5 dims[0] = 4; rank current dims
6 dims[1] = 6;
7 dataspace_id = H5Screate_simple (2, dims, NULL);
8 dataset_id = H5Dcreate (file_id,”A",H5T_STD_I32BE,
dataspace_id, H5P_DEFAULT,
H5P_DEFAULT,
H5P_DEFAULT);
9 status = H5Dclose (dataset_id);
10 status = H5Sclose (dataspace_id);
11 status = H5Fclose (file_id);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 58 www.hdfgroup.org
Code: Create a Dataset
1 hid_t file_id, dataset_id, dataspace_id;
. hsize_t dims[2];
. herr_t status;
.
. file_id = H5Fcreate (”file.h5", H5F_ACC_TRUNC,
H5P_DEFAULT, H5P_DEFAULT);
. dims[0] = 4;
. dims[1] = 6;
. dataspace_id = H5Screate_simple (2, dims, NULL);
Where to put it Datatype
8 dataset_id = H5Dcreate (file_id,”A",H5T_STD_I32BE,
dataspace_id, H5P_DEFAULT,H5P_DEFAULT,
H5P_DEFAULT);
Size & shape Properties
(Link Creation, Dataset
Creation and Access)
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 59 www.hdfgroup.org
Code: Create a Dataset
1 hid_t file_id, dataset_id, dataspace_id;
2 hsize_t dims[2];
3 herr_t status;
4 file_id = H5Fcreate (”file.h5", H5F_ACC_TRUNC,
H5P_DEFAULT, H5P_DEFAULT);
5 dims[0] = 4;
6 dims[1] = 6;
7 dataspace_id = H5Screate_simple (2, dims, NULL);
8 dataset_id = H5Dcreate (file_id,”A",H5T_STD_I32BE,
dataspace_id, H5P_DEFAULT, H5P_DEFAULT,
H5P_DEFAULT); Terminate access to
9 status = H5Dclose (dataset_id); dataspace, dataset, file
10 status = H5Sclose (dataspace_id);
11 status = H5Fclose (file_id);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 60 www.hdfgroup.org
Example Code - H5Dwrite
Dataset ID from
H5Dcreate/H5Dopen Memory Datatype
status = H5Dwrite (dataset_id, H5T_NATIVE_INT,
H5S_ALL,H5S_ALL, H5P_DEFAULT, wdata);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 61 www.hdfgroup.org
Partial I/O
status = H5Dwrite (dataset_id, H5T_NATIVE_INT,
H5S_ALL, H5S_ALL, H5P_DEFAULT,wdata);
Memory File Dataspace (disk)
H5S_ALL H5S_ALL
Dataspace
To Modify Dataspace:
H5Sselect_hyperslab
H5Sselect_elements
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 62 www.hdfgroup.org
Example Code – H5Dwrite
status = H5Dwrite (dataset_id, H5T_NATIVE_INT,
H5S_ALL, H5S_ALL, H5P_DEFAULT, wdata);
Data Transfer Property List
(MPI I/O, Transformations,…)
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 63 www.hdfgroup.org
Example Code – H5Dread
status = H5Dread (dataset_id, H5T_NATIVE_INT,
H5S_ALL, H5S_ALL, H5P_DEFAULT, rdata);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 64 www.hdfgroup.org
High Level APIs: HDF5 Lite (H5LT)
#include “hdf5_hl.h“
.
.
file_id = H5Fcreate(“file.h5",H5F_ACC_TRUNC,
H5P_DEFAULT, H5P_DEFAULT);
status = H5LTmake_dataset (file_id,“A",2,dims,
H5T_STD_I32BE, data);
status = H5Fclose (file_id);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 65 www.hdfgroup.org
Steps to Create a Group
1. Decide where to put it – “root group”
• Obtain location ID
2. Define properties or use H5P_DEFAULT
3. Create group in file.
4. Close the group.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 67 www.hdfgroup.org
Example: Create a Group
“/” (root)
A B
4x6 array of
integers
file.h5
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 68 www.hdfgroup.org
Code: Create a Group
hid_t file_id, group_id;
...
/* Open “file.h5” */
file_id = H5Fopen (“file.h5”, H5F_ACC_RDWR,
H5P_DEFAULT);
/* Create group "/B" in file. */
group_id = H5Gcreate (file_id,"B", H5P_DEFAULT,
H5P_DEFAULT, H5P_DEFAULT);
/* Close group and file. */
status = H5Gclose (group_id);
status = H5Fclose (file_id);
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 70 www.hdfgroup.org
HDF5 Tutorial and Examples
HDF5 Tutorial:
http://www.hdfgroup.org/HDF5/Tutor/
HDF5 Example Code:
http://www.hdfgroup.org/ftp/HDF5/examples/examples-by-api/
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 71 www.hdfgroup.org
The HDF Group
Thank You!
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 72 www.hdfgroup.org
Acknowledgements
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.
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 73 www.hdfgroup.org
The HDF Group
Questions/comments?
November 3-5, 2009 HDF/HDF-EOS Workshop XIII 74 www.hdfgroup.org
