EO Satellite Tasking Extension for SPS OGC 10-135
swes:extension eosps:ReferenceFeasibilityID
http:ws.spotimage.comspsfeasibilityF2AEA58FFA12B56CC eosps:ReferenceFeasibilityID
swes:extension ...
sps:Submit
Requirement http:www.opengis.netspecEOSPS2.0reqcoreref-feasibility-id-valid
Req 15. The ReferenceFeasibilityID XML element shall be valid with respect to the
spsRequestExtensions.xsd schema and inserted within an extension element of the
Submit or Reserve XML request.
7.1.4 Feasibility study model
7.1.4.1 Introduction
In addition to the basic information included in the feasibility response defined in the SPS standard, detailed feasibility study results required for proper operations of EO satellites
shall also be provided by an SPS supporting this extension. This information shall be inserted in status reports produced as the result of a feasibility request and retrieved either
directly with the GetFeasibility request or via a secondary GetStatus request. The FeasibilityStudy class described in this clause describes the information model to be used
to provide detailed feasibility study results.
Requirement http:www.opengis.netspecEOSPS2.0reqcorefeasibility-study-report
Req 16. A StatusReport describing the result of a feasibility study and with a request
status of ‘Accepted’ shall include an instance of the FeasibilityStudy class.
Note: Feasibility results can also be provided for information when the demand is not feasible i.e. the request status in the response to GetFeasibility is “Rejected”. In this
case, the response will generally contain an incomplete list of segments i.e. a portion of the region of interest is not covered by any of the segments in the list andor a list of
cells with at least some of them having a very low probability of success.
7.1.4.2 FeasibilityStudy Class
7.1.4.2.1 Description
The results of a feasibility study are composed of an overall feasibility assessment, plus a detailed feasibility, per cell or per segment, depending on the mission.
Copyright ©
2011 Open
Geospatial Consortium
51
OGC 10-135 EO Satellite Tasking Extension for SPS
For some EO systems, feasible acquisition segments can be estimated long in advance and be provided directly in the results. For each planned segment, several properties are
then specified such as the date and time of acquisition, the combination of platform, instrument and mode used to acquire the segment, acquisition angles and ground
footprint of the segment, etc... The customer can then see the exact segments that will be acquired for him.
For other EO systems, such as highly agile satellites, feasible segments are not known in advance due to the possibility of acquiring multiple areas of the earth at a given instant in
time i.e. by pointing the satellite. In such cases, a frequent re-optimization of the satellite work plan with respect to the latest weather conditions especially for optical
instruments or other criteria is often done in order to satisfy a maximum number of customers. The consequence is that only an estimated list of potential segments can be
generated with no certainty that these segments will actually be acquired exactly as planned.
One common method to solve the problem of work plan optimization for agile satellites is the division of the region of interest in several smaller sub-areas called grid cells that
are processed individually in a statistical manner. Since the actual chosensuccessful segment covering each cell is not known with certainty at the time of the feasibility study,
statistical information is instead given to indicate the chance of successfully covering each cell, as well as the overall chance of successfully covering the whole area before the
end of the requested time window. Note that these probabilities can take into account climate, weather and satellite workload conditions, as indicated in the feasibility study.
In such a case, the feasibility result contains a list of cells in addition to the list of planned segments planned segments are optional if cells are given. Each cell feasibility
assessment can also include information such as the estimated date of success and the date of the first possible attempt. For advanced users, it is also possible to include all
possible acquisition attempts for each cell instead of a single estimated segment per cell in the feasibility response.
7.1.4.2.2 Data model
The feasibility study is a top level class and aggregates either a list of segments, a list of cells or both as explained above. It shall be inserted directly in the extension slot of a
StatusReport element.
52 Copyright
© 2011
Open Geospatial
Consortium
