Introduction and Objectives
The demand for aerial and spatial imagery, and derived products, has been increasing over the years. At the same time, the technology has evolved allowing to produce a bigger variety of data with an increasing quality and accuracy. As a consequence of these advances, and the multiplication of deployed sensors, the amount of Earth Observation data collected and stored has exploded. For example, Envisat, launched in 2002, transmits 280 gigabytes of data every day, while the first three satellites of the Sentinel constellation beam together around 10,000 gigabytes in the same period. Better and more accurate data allow for new kinds of applications to be developed. Current high precision images permit analyzing phenomena that were not visible before. EO data have been recognized as critical to support major applications such as disaster and crisis management, and environmental (land, ocean and atmosphere) monitoring. Recently, decisions have been taken to ensure EO data will be available to anyone who needs them (see: Open access to Sentinel missions data: http://www.esa.int/esaEO/SEMXK570A2G_environment_0.html).
Data holders are now facing the problem of facilitating the access to their resources. Several initiatives have been taken during which Web portals have been developed allowing for resource providers to publish their services, and end-users to search for and obtain the EO products. ESA's Service Support Environment (SSE) is one such portal. These portals are however still too complex to be used by users who have limited knowledge of the Earth Observation domain in general, and in satellite imagery in particular. Users are accustomed to their own domain of activity and the associated terminology and should not have to learn many EO domain specific terms.
The objective of RARE is to build a distributed software system accessible through a Web-based user interface that allows searching for EO-related resources such as satellite images, maps and geo-localized features (e.g. coverages and points of interests) using application domain terms, that is, using the terminology any potential user is accustomed with. RARE will provide a centralized service that interfaces with a number of on-line resources that were not integrated in the past. These resources include:
- a terminology service supporting the navigation facility between related application terms,
- a query analyzer that augments the knowledge with unforeseen concepts and relations extracted from the Internet,
- gazetteers used to resolve place names,
- various reasoners mapping the application terms selected by the users to product categories, and
- a centralized catalogue service that collects the properties of on-line resources registered in the KEO registry and other remote catalogues.
RARE will hide as much as possible the technical information related to the resources themselves: the system determines, based on elaborate mapping rules defined with the help of domain experts, which categories of resources are valuable in regards to the application terms entered by the users. This mechanism greatly reduces the time and the knowledge needed to search for, and obtain, the right resource for the right problem. It brings the advantages of EO-derived resources into the users domain of interest with minimal effort.
RARE will develop a software platform that:
1) provides a Web-based user interface driven by application terms (domain specific, i.e. land, ocean and atmosphere monitoring, emergency response and security) users are familiar with;
2) includes an initial set of application domains and may be extended to new domains;
- terms searched by the users to application terms;
- location names to geographical coordinates (using gazetteers);
- application terms, geographical coordinates and time constraints to categories of EO products;
- EO product categories to actual services.
4) gives access to any type of geo-localizable resources: pictures, maps, features, coverages, processors;
5) interfaces with existing catalogs and services using standardized protocols (OGC, ISO);
6) interfaces with a client application to visualize the data.
Using the RARE Web interface, the user can access EO products by providing a query such as:
In this example:
- "feluy" may be a city in Belgium,
- "total" will be resolved to the petroleum company (after interactive disambiguation),
- the time period is around an explosion that occurred in the year 2009, and
- the EO products may be a satellite image of 1.5m resolution, an infrared HRS image with 0.5m resolution, population density in the area, infrastructure in the area, heat detection algorithms, etc.
At the start of the project, a survey of the state-of-the-art ontology integration methodologies and a review of existing semantic architectures are conducted. These preliminary activities are performed during the project definition phase, in parallel to the work on the specification of the user and the software requirements. The remaining of the project follows the classical flow used to design, implement, integrate and validate software systems. A knowledge engineering activity will however be performed during the detailed design and implementation phase. During this activity the Multi-domain ontology will be extended and the reasoning rules will be specified.
The following results are expected from the RARE project:
- Contribution to OGC standards, in particular to the semantic capabilities of the catalogue service.
- Extension of the OTE Terminology / EO Ontology to the five GMES application domains.
- Design of an EO products categorization/classification scheme.
- Conversion service transforming query strings expressed in general terms to requests containing application domain terms and normalized geographic and time constraints.
- Reasoning services mapping normalized requests to product categories, and ultimately to available datasets.
- Web user interface for interacting with the resolving and reasoning services.
|KOM||--||December 2010||Kick Off Meeting|
|TKO||T0||February 2011||Technical kick-off|
|SRR||T0+5M||July 2011||System Requirements Review|
|PDR||T0+9M||November 2011||Preliminary Design Review|
|CDR||T0+19M||December 2012||Critical Design Review|
|PAR||T0+23M||July 2013||Preliminary Acceptance Review|
|FP||T0+24M||September 2014||Final Presentation|
|End||T0+30M||February 2015||End of Warranty Period|
Space Applications Services, Epistematica