Easy Access of NASA HDF data via OPeNDAP
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The document discusses the HDF Group's implementation of OPeNDAP for accessing NASA's HDF data, providing an overview of the software framework and its relevance to the Earth science community. It covers the structure of OPeNDAP data objects, limitations in visualization, and the support for various HDF products, including HDF4 and HDF5. A live demo and additional resources are also mentioned to facilitate the accessibility of HDF data.
![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.
September 28,2010
HDF/HDF-EOS Workshop XIV
24
www.hdfgroup.org](https://image.slidesharecdn.com/opendaptutorialws14-140217085857-phpapp01/85/Easy-Access-of-NASA-HDF-data-via-OPeNDAP-24-320.jpg)
Easy Access of NASA HDF data via OPeNDAP
- 1. The HDF Group Easy Access of NASA HDF data via OPeNDAP Kent Yang and Joe Lee The HDF Group September 28,2010 HDF/HDF-EOS Workshop XIV 1 www.hdfgroup.org
- 2. Easy September 28,2010 HDF/HDF-EOS Workshop XIV 2 www.hdfgroup.org
- 3. Outline • Introduction to OPeNDAP • HDF4/5-OPeNDAP Handlers • Live Demo September 28,2010 HDF/HDF-EOS Workshop XIV 3 www.hdfgroup.org
- 4. OPeNDAP • A software framework that allows simple access to remote data • Client-server model • Servers make the local data accessible remotely • Clients make applications easily access to remote served data • Widely used by Earth Science Community • URL: http://www.opendap.org/ September 28,2010 HDF/HDF-EOS Workshop XIV 4 www.hdfgroup.org
- 5. Access HDF via FTP Aqua/Aura Users IDL AIRS/OMI FTP Local HDF Files September 28,2010 FTP Clients FTP Servers HDF/HDF-EOS Workshop XIV HDF Files 5 www.hdfgroup.org
- 6. OPeNDAP Concept Typical Remote Access View Data (User) FTP/HTTP Remote Data (HDF4/5) Visualization tools Visualization (e.g., grads) Tools (gradsdap) Handler (hdf4/5_handler) Client Library (libnc_dap) Server (Hyrax) Data Access Protocol (DAP) via Internet September 28,2010 HDF/HDF-EOS Workshop XIV 6 www.hdfgroup.org
- 7. Access HDF via OPeNDAP Aqua/Aura Users IDV HyraxHANDLER HDF AIRS/OMI libnc-dap DAP Visualization Tools September 28,2010 OPeNDAP Clients OPeNDAP Servers HDF/HDF-EOS Workshop XIV HDF Files 7 www.hdfgroup.org
- 8. OPeNDAP Data Types • OPeNDAP provides three basic data objects: - data descriptor structure (.dds) syntactic metadata – rigid - data attribute structure (.das) semantic metadata – flexible - data (.dods) - the actual data in a binary structure • Data are requested with a URL September 28,2010 HDF/HDF-EOS Workshop XIV 8 www.hdfgroup.org
- 9. OPeNDAP Servers CODAR netCDF HDF4/5 Matlab Data Data CODAR Data netCDF Tables SQL FITS CDF Data Data Data Data Data Data Matlab HDF4/5 September 28,2010 Data DSP Flat Binary JGOFS DSP FITS JDBC HDF/HDF-EOS Workshop XIV CEDAR General Data Data ESML FreeFrom CDF CEDAR 9 www.hdfgroup.org
- 10. OPeNDAP Clients netCDF C Ferret GrADS September 28,2010 netCDF Java IDV VisAD ncBrowse Matlab Client IDL Client Matlab IDL HDF/HDF-EOS Workshop XIV Access 10 Excel www.hdfgroup.org
- 11. Outline • Introduction to OPeNDAP • HDF4/5-OPeNDAP Handlers • Live Demo September 28,2010 HDF/HDF-EOS Workshop XIV 11 www.hdfgroup.org
- 12. Enhanced HDF4 Handler Enhanced HDF4 HANDLER Aura Users IDV MODIS Swath w/ Dim. Map Hyrax libnc-dap DAP Visualization Tools September 28,2010 OPeNDAP Clients OPeNDAP Servers HDF/HDF-EOS Workshop XIV HDF4 Files 12 www.hdfgroup.org
- 13. An example: Access HDF data via OPeNDAP Swath with Dimension Map September 28,2010 HDF/HDF-EOS Workshop XIV 13 www.hdfgroup.org
- 14. HDF-EOS2 Products Supported • GES DISC • AIRS / MERRA / TOMS • LAADS / LP DAAC / NSIDC • Many MODIS products • NSIDC • AMSR_E / NISE • LaRC • MISR / MOPITT / some CERES(TRMM) September 28,2010 HDF/HDF-EOS Workshop XIV 14 www.hdfgroup.org
- 15. Pure HDF4 Products Supported • GES DISC • TRMM L1B, L2B Swath • TRMM L3 Grid 42B & 43B products • OBPG (Ocean Color) • SeaWiFS / MODIST / MODISA • CZCS / OCTS September 28,2010 HDF/HDF-EOS Workshop XIV 15 www.hdfgroup.org
- 16. Pure HDF4 Products Supported • CERES • • • • • • • September 28,2010 CER_AVG CER_ES4 CER_ISCCP-D2like-Day CER_ISCCP-D2like-GEO CER_SRBAVG CER_SYN CER_ZAVG HDF/HDF-EOS Workshop XIV 16 www.hdfgroup.org
- 17. Limitations • Reasons for Visualization Failures • IDV / Panoply / Java Heap Memory • Network / DAP (e.g., max HTTP header size) • Can’t retrieve key information correctly (e.g., LAMAZ projection) from data • Unable to harmonize with CF-conventions (e.g., FillValue inside latitude and longitude) September 28,2010 HDF/HDF-EOS Workshop XIV 17 www.hdfgroup.org
- 18. Limitations(continued) • HDF-EOS2 + additional HDF4 objects • Additional HDF4 objects will be ignored. • The rest of pure HDF4 products not listed in previous slides are not tested and may not be visualized by Java OPeNDAP Clients. September 28,2010 HDF/HDF-EOS Workshop XIV 18 www.hdfgroup.org
- 19. HDF-EOS5 products Supported • OMI Swath, Grid • MLS/HIRDLS Swath • TES Grid September 28,2010 HDF/HDF-EOS Workshop XIV 19 www.hdfgroup.org
- 20. Learning Curve of accessing HDF data NCL From the ESIP wiki page: http://wiki.esipfed.org/index.php/Making_Science_Data_Easier_to_Use_with_OPeNDAP Making Science Data Easier to Use with OPeNDAP September 28,2010 HDF/HDF-EOS Workshop XIV 20 www.hdfgroup.org
- 21. Live Demo September 28,2010 HDF/HDF-EOS Workshop XIV 21 www.hdfgroup.org
- 22. OPeNDAP HDF4/HDF5 handlers • Source codes and RPMs can be found under http://opendap.org • Demo HDF5/HDF4 servers http://hdfeos.org/zoo/hdf5_handler/ http://hdfeos.org/zoo/hdf5_handler/ • Currently NASA GES DISC has installed both OPeNDAP HDF4 and HDF5 handlers September 28,2010 HDF/HDF-EOS Workshop XIV 22 www.hdfgroup.org
- 23. The HDF Group Thank you ! September 28,2010 HDF/HDF-EOS Workshop XIV 23 www.hdfgroup.org
- 24. 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. September 28,2010 HDF/HDF-EOS Workshop XIV 24 www.hdfgroup.org
- 25. The HDF Group Questions/comments? September 28,2010 HDF/HDF-EOS Workshop XIV 25 www.hdfgroup.org
- 26. Our Work • Let Visualization Clients Access HDFEOS2 and HDF4 files September 28,2010 HDF/HDF-EOS Workshop XIV 26 www.hdfgroup.org
- 27. HDF5-OPeNDAP Handler Update • Support Aura HDF-EOS5 OMI Swath • Access some files that follow HDF5 Dimension Scale Specification • Support Aura HDF-EOS5 MLS September 28,2010 HDF/HDF-EOS Workshop XIV 27 www.hdfgroup.org
Editor's Notes
- #3: The Earth Observing System Project Science Office -> eospso.gsfc.nasa.gov (Information about Earth Observing System)SDP Toolkit/HDF-EOS: http://newsroom.gsfc.nasa.gov/sdptoolkit/toolkit.html HDF Group website: http://hdfgroup.orgBut HDF-EOS Tools and Information Center http://hdfeos.org or http://hdfeos.net Screenshot of http://hdfeos.orgExplain two reasons for this work:We’ve done this work in the past few months.Some information of tools are out of date. Need to be updated.Requests for more information such as examples.
- #6: When it comes to the network access of data, people think of this manner.OPeNDAP is an open implementation of easy data access through visualization tools like IDV.Our work bridges the existing OPeNDAP framework and HDF so that visualization is possible over the Internet.
- #8: For people who are not familiar with OPeNDAP, I’ll explain how OPeNDAP works with HDF.OPeNDAP is an open implementation of easy data access through visualization tools like IDV.Our work bridges the existing OPeNDAP framework and HDF so that visualization is possible over the Internet.
- #13: I will quickly go over hdf5 handler update.First, I’ll describe the problems of the old handlers and then what we did, limitations of our solution and future work.HE2 to EOS2.
- #14: Here’s one proof that using HDF-EOS2 library really helps to visualize something that wasn’t possible with a parser-based solution.
- #15: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #16: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #17: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #18: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #19: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #22: IDV Examples from hdfeos.org.Demo server from hdfgroup.org.
- #23: We have summarized the top 7 reasons why some HDF-EOS will fail.We also listed some sample files that will not work with HDF4 handler.Here are screenshots of website.Make animation – screen shots in between texts.
- #27: Therefore, our primary goal is to enhance it so that it can visualize data instantly.
- #28: For HDF5 handler, we added support for some OMI swath file.Next, we added a support for some files that follow HDF5 dimension scale models.Finally, we changed short name option. This helps GrADs users to visualize data more quickly using the simple ‘sdfopen’ command.