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Sketch for using TSML domain-range type timeseries in aerodrome weather forecast #19

Closed ilkkarinne closed 3 weeks ago

ilkkarinne commented 3 months ago

As a response to the requirement for including observable properties with more than one component (wind speed & direction etc.), I drafted an example of using a modified TSML 1.3 TimeseriesDomainRange element as the forecast value container: https://github.com/spatineo/iwxxm-sx/blob/ee59d0dced89b16e94f741b4a67e9a724ee3fbd3/IWXXM/examples/AerodromeWeatherForecast-TSML-DR-Example.xml

In TSML, the domain-range timeseries data model is inherited from the GML Coverage Schema (GMLCOV) 1.0, thus GMLCOV schema is also imported in addition to TSML 1.3. As in the TVP example at #18 previously, the O&M XML Schema dependency is cut out by slightly modifying the TSML 1.3 XML Schema files.

I think the model seems to work reasonably well at least for the simple examples I could think of. Whether it makes sense to actually import the TSML and GMLCOV schemas in IWXXM or create the implementations of the required elements within IWXXM , remains another question.

ilkkarinne commented 3 months ago

Modified DR example and TSML 1.3 schemas to use CIS 1.1 instead of (deprecated) GMLCOV: https://github.com/spatineo/iwxxm-sx/blob/6cbf9c9d95af81d404d1364f103502a951503543/IWXXM/examples/AerodromeWeatherForecast-TSML-DR-Example.xml

ilkkarinne commented 3 months ago

As I learned from the OGC Member Meeting last week, one cannot use ISO 8601 time stamps as a coordinate reference system in the Coverage / Grid, as they do not form a TemporalCRS one could do arithmetic with. Instead one can use UnixTime which is one of the formally registered OGC TemporalCRS:es (http://www.opengis.net/def/crs/OGC/0/UnixTime). Unix time being just an integer count of seconds since 1970-01-01 00:00:00 UTC forms a proper CRS, although it's not as human-readable as ISO 8601 timestamps.

This change has been made to the DR-example in commit 951bbc of AerodromeWeatherForecast-TSML-DR-Example.xml

ilkkarinne commented 2 months ago

As I've managed to introduce record-type values for the TSML TVP encoding IWXXM profile, I feel that there is no more need for the otherwise more clumsy DR encoding in the scope of the aerodrome forecast.

ilkkarinne commented 3 weeks ago

Closing, as the TVP option seems to provide a better alternative to the issue