An HDF-EOS file contains one or more HDF-EOS data objects along with metadata. It provides geolocation information coupled to data, standardized subsetting by geography or time, and ECS metadata for archiving and distribution. The difference between HDF and HDF-EOS is at the object level within a file, not the file type itself. A file can contain both HDF and HDF-EOS objects.

1. An Overview of
HDF-EOS
(Part II)
Doug Ilg
Raytheon STX
Doug.Ilg@gsfc.nasa.gov
(301) 441-4089
1

2. Outline
The Swath Interface
What is an HDF-EOS File?
2

3. In
str
u
me
nt
Pa
th
Swath Data Sets
Instrument
Profiles
In
str
u
m
en
t
Pa
th
Instrument
Scan Lines
Along Track
Along Track
3

4. A Swath Structure
Dimension
Name: Scan
Size: 16
“Temp”
“Time”
Dimension
Name: Track
Size: 42
Dimension
Name: Geotrack
Size: 21
Map1
DataDimension: “Track”
Geodimension: “Geotrack”
Offset: 1
Increment: 2
4

5. Components of the Swath
Interface
Access
Definition
Basic I/O
Inquiry
Utility
Subset
5

6. Tips on Writing a Swath
Order of calls is significant:
– define dimensions before using them to
define fields of maps
– setting a compression method affects all
subsequently defined fields
Unless a dimension map is defined, a 1to-1 mapping is assumed during
subsetting. This can produce strange
results.
6

7. Swath Subsetting Features
By Time
– SWdeftimeperiod/SWextractperiod
By Geolocation
– SWdefboxregion/SWextractregion
By “Vertical” field
– SWdefvrtregion/SWextractregion
Tip: use Time or Geolocation first, then
Vertical
7

8. Compression Methods for
Swaths
Run-Length Encoding
Adaptive Huffman
Gzip
8

9. Question:
What’s an HDF-EOS File?
9

10. Some Answers
ECS: An HDF file with ECS metadata
Any file with an HDF-EOS object in it
A file with only HDF-EOS objects in it
10

11. My Answer
You’ve asked the wrong question.
The difference between HDF and HDFEOS is at the object level, not the file
level.
11

12. Key
An HDF file
HDF-EOS
One or more HDF-EOS data objects
with attendant structural metadata
ECS
Metadata
Core and possibly Archive
metadata
HDF
One or more HDF data objects
12

13. HDF
•Portability
•Elementary data access
•Basic self-description
HDF-EOS
• Geolocation information
tightly coupled to data
• Fully standardized
geographical subsetting
• Moderate self-description
ECS
Metadata
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
13

14. HDF
An HDF file with a set of
HDF data objects
Services Provided
•Portability
•Elementary data access
•Basic self-description
Services Not Provided
• Geolocation information
tightly coupled to the data
• Fully standardized
geographical subsetting
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
14

15. HDF-EOS
An HDF file with a set of
HDF-EOS data objects
Services Provided
• Portability
• Elementary data access
• Moderate self-description
• Geolocation information
tightly coupled to the data
• Fully standardized
geographical subsetting
Services Not Provided
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
15

16. Services Provided
• Portability
• Elementary data
access
HDF-EOS
• Moderate selfdescription
• Geolocation information
HDF
tightly coupled to some
of the data
• Partially standardized
geographical subsetting
An HDF file with a mixed
Services Not Provided
set of HDF-EOS and HDF • ECS ingest, archiving,
data objects
search, and distribution
• Enhanced self-description
• Fully standardized
geographical subsetting
16

17. HDF
ECS
Metadata
An HDF file with a set of
HDF data objects with
ECS metadata
Services Provided
• Portability
• Elementary data access
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
Services Not Provided
• Geolocation information
tightly coupled to the data
• Fully standardized
geographical subsetting
17

18. HDF-EOS
ECS
Metadata
An HDF file with a set of
HDF-EOS data objects
with ECS metadata
Services Provided
• Portability
• Elementary data access
• Geolocation information
tightly coupled to the data
• Fully standardized
geographical subsetting
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
Services Not Provided
• None
18

19. HDF-EOS
HDF
ECS
Metadata
An HDF file with a
mixed set of HDF and
HDF-EOS data objects
with ECS metadata
Services Provided
• Portability
• Elementary data access
• Geolocation information
tightly coupled to some of
the data
• Partially standardized
geographical subsetting
• ECS ingest, archiving,
search, and distribution
• Enhanced self-description
Services Not Provided
• Fully standardized
geographical subsetting
19