Page 1 CSISS LCenter for Spatial Information Science and Systems 11/08/2007 Implementation of OGC Web Coverage Service Using HDF5/HDF-EOS5 as the Base File Format Peichuan Li, Ph.D. Liping Di, Ph.D. Genong (Eugene) Yu, Ph.D. Center for Spatial Information Science and Systems (CSISS) George Mason University 6301 Ivy Ln, Suite #620 Greenbelt, MD

Page 2 CSISS Center for Spatial Information Science and Systems 10/08/2007 Contents Introduction Methodology Samples of system implementation Discussion and Conclusion

Page 3 CSISS Center for Spatial Information Science and Systems 10/08/2007 Introduction 1.Activities & Purpose –The requirement for the ongoing Sensor Web project conducted at CSISS ; –Research its possibility for WCS to serve new kinds of base data that it is different from what we have previously done;

Page 4 CSISS Center for Spatial Information Science and Systems 10/08/2007 Introduction (Cont.) 2.Objectives –Final Goal: To implement a Web Coverage Service (WCS) for describing and delivering multidimensional geospatial coverage data in HDF-EOS 5/HDF-5 format. The services followed OGC WCS Specification [1] The Web Coverage Service (WCS) implemented provides the Transaction operation. [2] The transaction provides the flexibility of re- serving derived results in standard geospatial services. –Phrases: Phrase 1: –Focus on Aura/HIRDSL L2(hdfeos5) base data; –Implement general operations of WCS. i.e. getCoverage, getCapabilites, DescribeCoverage…; –Provide he5 Swath and netCDF responding to client’s request; Phrase 2: –Add Transaction operation; –Provide Aura / plain hdf5 base data support;

Page 5 CSISS Center for Spatial Information Science and Systems 10/08/2007 Introduction (Cont.) 3.About Aura HIRDLS data [3] –HIRDLS is an infrared limb-scanning radiometer designed to sound the upper troposphere, stratosphere, and mesosphere to determine temperature; –HIRDLS measures the concentrations of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, CFC11, CFC12, ClONO2, and aerosols; –Locations of polar stratospheric clouds and cloud tops. –The goals were to provide sounding observations with horizontal and vertical resolution superior to that previously obtained; –To observe the lower stratosphere with improved sensitivity and accuracy; and to improve the understanding of atmospheric processes through data analysis, diagnostics, and use of two- and three-dimensional models.

Page 6 CSISS Center for Spatial Information Science and Systems 10/08/2007 Introduction (Cont.) About AutoChem [4] –AutoChem is a NASA release software that constitutes an automatic computer code generator and a documenter for chemically reactive systems written by David Lary between 1993 and the present. It was designed primarily for modeling atmospheric chemistry, and in particular, for chemical data assimilation.NASADavid Lary atmospheric chemistrydata assimilation

Page 7 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology 1.Architecture Web user AutoChe m System Other App. System WCS_T Server Aura/HIRDLS Data Files Web Protocol WCS Comm. Interface WCS_T Interface

Page 8 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology –The Component diagram

Page 9 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) –Sequence diagram

Page 10 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) 2.The difficulties to be solved A.Representing, defining and restoring of the Line string coverage [5] The definition of OGC Coverage: –GIS coverages (including the special case of Earth images) are two- (and sometimes higher-) dimensional metaphors for phenomena found on or near a portion of the Earth’s surface. –A coverage is a special case of (or a subtype of) feature. –A feature with geometry has one or more properties taking values that are OpenGIS geometries (as defined in Topic 1, and in the Implementation Specifications.)

Page 11 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) The coverage we used from HE5/HIRDLS is different from what we met previously. Geolocation information is based on line string geometry, in contrast to image and grid coverage. The geolocation and other location information were mapped by “Time” information indirectly. (Source comes from [6])

Page 12 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) –Define an abstract data model (ADM) to present coverage with line string geometry in memory, mapping He5/HIRDLS Swath data to ADM, in addition to manipulate and process coverage on ADM. –Dataset in ADM is a one/two (not more than two) dimension array. One of the dimensions is nTime dimension associated with Time and then mapped to Longitude/Latitude indirectly; –One coverage is identified by its name ID and correspond to one Swath data field in HIRDLS data file. e.g. HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O3 File Name Data TypeSwath nameData Field name

Page 13 CSISS Center for Spatial Information Science and Systems 10/08/2007 B.Sub-setting operation for this particular kind of coverage –Domain sub-setting: We use Time sequence parameter to process Domain sub-setting requested from user. The Domain sub- setting by geographic Bounding Box will be implemented in future. The extent of nTime is about 24h one day that are restricted by HIRDLS data. Time granule is one second (the time frame and representation followed Aura/HIRDLS data production specification). Methodology (cont.)

Page 14 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) –Range sub-setting: Range sub-setting extracts data on non-nTime dimensions that are defined in ADM of coverage. It will depend on available number of dimensions and range of its value. The parameter that client requested for range sub- setting is defined by WCS spec.

Page 15 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) –Output format: For the reason of special coverage to be defined, the restore file format for outputting coverage adopts he5/Swath and NetCDF format. Another reason to adopt the he5/Swath is due to the specific requirement of AutoChem application.

Page 16 CSISS Center for Spatial Information Science and Systems 10/08/2007 Methodology (cont.) C.Strategy of system design and development 1.Based-on object-oriented design and programming 2.WCS_T request messages follow OGC WCS_T Specification. 3.Wrap he5 c interface into c++ implementation class 4.Platform of development, testing and running; 1.eclipse 2.Linux 5.Utilize open source software and tools 1.expat and scew libraries for XML parser 2.Hdf , hdf-eos , netCDF c/c++ lib 3.Other required c/c++ lib and tools

Page 17 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation Current constraints of services routines: –Base data must be Aura/HIRDLS. –Domain sub-setting only supports Temporal Period request. –Output format only supports he5 and netCDF. –For the sake of research, services routines only complete GetCoverage operation up to now.

Page 18 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) Samples for “Get Method”: –Sample 1: with Domain and Range sub-setting bin/he5Swath?SERVICE=WCS&VERSION=1.1.0&REQU EST=GetCoverage&IDENTIFIER=HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O3&TimeSequence= / &FORMAT=image/hdf eos5&RangeSubset=O3:NONE[Pressure[ , , ]]

Page 19 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) –Sample 2: with Range sub-setting and without Domain sub setting bin/he5Swath?SERVICE=WCS&VERSION=1.1.0&REQU EST=GetCoverage&IDENTIFIER=HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O3&FORMAT=image/ hdfeos5&RangeSubset=O3:NONE[Pressure[ , , ]]

Page 20 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) –sample 3: with Domain sub-setting and without Range sub-setting bin/he5Swath?SERVICE=WCS&VERSION=1.1.0&REQUEST=Get Coverage&IDENTIFIER=HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O3&TimeSequence= / &FORMAT=image/hdfeos5 –sample 4: without Domain and Range sub-setting bin/he5Swath?SERVICE=WCS&VERSION=1.1.0&REQUEST=Get Coverage&IDENTIFIER=HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O3&FORMAT=image/hdfeos5

Page 21 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) Post Method: –WCS XML Request Message

Page 22 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) - request HIRDLS2_v c3_2007d053.he5:SWATH:HIRDLS:O O3 None Pressure

Page 23 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.) - response WCS XML Respond Coverage created from GetCoverage operation request to a WCS

Page 24 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.)

Page 25 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.)

Page 26 CSISS Center for Spatial Information Science and Systems 10/08/2007 Samples of system implementation (Cont.)

Page 27 CSISS Center for Spatial Information Science and Systems 10/08/2007 Discussion & Conclusion Aura/HIRDLS data can be served effectively through the combination of powerful HDF-EOS and WCS –WCS provides standard interfaces to enable the access of Aura/HIRDLS data by geospatial applications. –WCS_T provide a transparent, standard mechanism for the transaction of geospatial data in the Web environment. –This WCS can be consumed by other Web services easily through its standard interfaces. It is realistic to chain different WCS into a complex composite service and better serve specific, advanced applications, e.g. application in sensor web project.

Page 28 CSISS Center for Spatial Information Science and Systems 10/08/2007 Discussion & Conclusion The work in future –To complete other required operations (e.g. getcapabilities, describeCoverage, transaction.) –Provide support for coverage request with BBox parameters and one more coverage output. –Provide support for composing BBox and Temporal Period request.

Page 29 CSISS Center for Spatial Information Science and Systems 10/08/2007 Reference 1.OGC r8, , “Web Coverage Service (WCS) Implementation Specification, Version: 1.1.0”. 2.OGC , “Web Coverage Service (WCS) — Transaction operation profile, Version: 1.1.0”. 3.July 1, 2006, “A Short Guide for V 2.00 Level-2 Data from HIRDLS PI”, from guide-Level2data_InitialRelease.pdf. 4."AutoChem Wiki." from 5.OGC , “The OpenGIS® Abstract Specification Topic 6: The Coverage Type and its Subtypes, Version 4 ” June 2006, “HIRDLS Version 2.0 Level 2 Data Description Quality Documents”, from ata_Description_InitialRelease.pdf

Page 30 CSISS Center for Spatial Information Science and Systems 10/08/2007 Acknowledgements This study has been supported by two NASA-funded projects: NASA AIST-QRS (PI: Dr. John F. Moses, Co-I: Dr. Liping Di, Dr. Wayne Feltz, Dr. Jason Brunner, Dr. Robert Rabin) and NASA AIST (PI: Dr. Liping Di, Co-I: Dr. James Smith, Dr. David Lary). This study is also partially supported by the National Basic Research Program (973 program) of China: 2006CB (PI: Dr. Jianya Gong).

Page 31 CSISS LCenter for Spatial Information Science and Systems 11/08/2007 Questions?

Page 32 CSISS LCenter for Spatial Information Science and Systems 11/08/2007 Thanks