An Overview of HDF-EOS (Part II)

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HDF AND HDF-EOS WORKSHOP II (1998)

Source: http://hdfeos.org/workshops/ws02/presentations/ilg2/ilg2.ppt

Slide 11 discusses the key difference between HDF and HDF-EOS: object level, not file-level.

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An Overview of HDF-EOS (Part II)

  1. 1. An Overview of HDF-EOS (Part II) Doug Ilg Raytheon STX Doug.Ilg@gsfc.nasa.gov (301) 441-4089 1
  2. 2. Outline The Swath Interface What is an HDF-EOS File? 2
  3. 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. 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. 5. Components of the Swath Interface Access Definition Basic I/O Inquiry Utility Subset 5
  6. 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. 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. 8. Compression Methods for Swaths Run-Length Encoding Adaptive Huffman Gzip 8
  9. 9. Question: What’s an HDF-EOS File? 9
  10. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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

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