Published in: J. STROBL and C. BEST (Eds.), 1998: Proceedings of the Earth Observation & Geo-Spatial Web and Internet Workshop '98 = Salzburger Geographische Materialien, Volume 27. Instituts für Geographie der Universität Salzburg. ISBN: 3-85283-014-1

AGADES
Experimentation with SPOT Data and
Integration in the CIP Framework

Thierry Levoir,

CNES, DGA/T/TI/PS/TD
18, avenue Edouard Belin
31055 Toulouse Cedex, FRANCE
E-mail : Thierry.Levoir@cst.cnes.fr

Abstract :

This is an experience report from the AGADES project which is conducted at the French Space Agency (CNES) in Toulouse, France. AGADES is the acronym for "Accès Généralisé aux Données Spatiales", Generalized Space Data Access System. The project demonstrates the possibility of constructing a generic system allowing high level access to results from different experiments and missions (EO, Space Physics, ...). A good example : AGADES has been used to access SPOT data by CNES user. We are working now to determine how such a system can be integrated in the CEOS Interoperability approach CIP (Catalog Interoperability Protocol).

Introduction : AGADES

With regards to modeling, the main system components are as follows :

a metadata management function based on an object model,
a physical data storage function compatible with the IEEE mass storage reference model,
a metadata access function allowing users to identify available data, to display available browse items and to make out orders for data,
data order processing and users delivery functions.

The main system architecture components are as follows :

an O2 (Object-Oriented Database System) metadata management data base,
a long term physical storage and conservation service set up by CNES and known as STAF,
a software package providing in particular for system protection, data protection and implementation of generic data extraction mechanisms,
a WWW server.

The following aspect regarding standardization and associated generic tools are emphasized :

standardization of dates and times in compliance with CCSDS recommendations,
standardization of data description in the EAST language (Enhance Ada SubSet - CCSDS panel 2),
standardization of browsing images in Archimede format (set up by CNES).

The genericness is the main point of this project and must be considered on several levels :

the data format,
processing on these different data formats,
means of assistance with the selection,
the interface,
criteria of data research,
the available delivery means for users,
the protection of data.

Accessing Spot Data with AGADES

The goal was to give an access to the new SPOT archive for the CNES Images Quality service.

We include in AGADES 53 attributes to select and order SPOT DATA :

ARCHIVE_PRODUCT_ID
| SATELLITE_ID.
| | FAMILY_NAME
| | NUMBER
| | INTERNATIONAL_CODE
| SENSOR_ID.
| | FAMILY_NAME
| | NUMBER
| LEVEL
| DESCRIPTION
| REFERENCE


PROCESSING_INFORMATION.
| RECEIVING_STATION
| | COUNTRY
| | AGENCY
| | STATION
| | FACILITY
| | SOFTWARE_RELEASE
| PROCESSING_FACILITY_NAME
| | COUNTRY
| | AGENCY
| | STATION
| | FACILITY
| | SOFTWARE_RELEASE


GENERIC_DATA_BLOCK.
| DATATION.
| | VIEWING
| | RECEIVING
| PASS_DESCRIPTIONS.
| | VIEWING.
| | | CYCLE_DURATION
| | | ORBIT_NUMBER
| | RECEIVING.
| | | CYCLE_DURATION
| | | ORBIT_NUMBER

SENSOR_DATA_BLOCK.
| PARAMETER_SETTINGS.
| | VIEWING_MODE
| | SATELLITE_ID.FAMILY_NAME
| | SATELLITE_ID.NUMBER
| | SATELLITE_ID.INTERNATIONAL_CODE
| | SENSOR_ID.FAMILY_NAME
| | SENSOR_ID.NUMBER
| | SENSOR_CONFIGURATION.LAMP
| | SENSOR_CONFIGURATION.B2_BAND
| | MIRROR_STEP
| | FOCUS_STEP
| | TRANSMISSION_MODE
| | CIPHERING_KEY
| | CHANNEL_NUMBER
| | CODING_MODE
| | TEST_FLAG
| | CALIBRATION_MODE
| | ON_BOARD_TAPE_COUNTERS.
| | | START_OF_SEGMENT
| | | END_OF_SEGMENT
| | SUB_SEGMENTS.
| | | NUMBER_OF_SUB_SEGMENTS
| | | LIST_OF_SUBPARAMETERS( 1..number_of_sub_seg).
| | | | NUMBER_OF_BANDS
| | | | SUB_SEGMENT_LOCATION.
| | | | | START.FRAME_NUMBER
| | | | | START.DATE
| | | | | END.FRAME_NUMBER
| | | | | END.DATE
| | | | COUPLING_MODE
| | | | COUPLED_MODE_FLAG
| | | | SPECTRAL_BAND
| | | | | NAME
| | | | | GAIN_NUMBER
| | MIR_MODE

The user after selecting one or more criteria can browse the results to define which data to order. The user doesn't access image browses data, because of their size, but access textual browses describing the data.

The recovery of the resulting files is done by FTP.

AGADES and CIP

Because of the success of AGADES experimentation with SPOT DATA, we're working on a new way to improve AGADES, in including it in the CIP framework.

The first STEP is to find the commonality between AGADES and the CIP.

The Object oriented data model

In the two cases, the main concepts of the object oriented approach are :

concept of "collections" and "groups of collections" (logical objects) : construction of a directed graph binding these nodes
concept of criteria associated to each graph node and allowing further selection (to lower graph levels)

CIP collection view

A user will have multiple methods to discover items in collections :

Collection Discovery : determine all collections which may be of interest
Collection Navigation : allows the user to examine collections related to a collection
Collection Searching : provide searches descending in the collection tree
Collection Locating : directly find a collection

In AGADES the definition of abstractions (to be implemented later in development) will allow to insert all CIP attributes, such as :

Collection Type
Creation Date
Keywords
...

Associated with the abstraction of "criterion" (whether it allows for example temporal selection or geographical selection or it implements dissemination user choices), we can integrate methods described above.

In a general point of view, we observe that there are sameness between the CIP and AGADES, but there are also lots of differences : Z39.50 protocol, Guide, Browse, . ..

Conclusion

CIP : A Catalogue Site Internal Architecture