The logical model goes like this: A Feature Source - Has 1..n spatial contexts - Each spatial context is uniquely named - Has 1..n feature classes - Each feature class has a designated logical geometry property - That geometry property has a spatial context association (to an existing name spatial context in the Feature Source)
Thus a layer's spatial context is the spatial context of the chosen geometry property of the feature class it is referencing. You don't assign a spatial context to a layer, you assign a feature class/geometry and the layer picks up the referenced spatial context from that. Now seeing you are talking about PostGIS in your other un-answered post, let me try to have a reasonable guess at how the FDO provider translates the PostGIS database into this logical model A Feature Source (A connection to a PostGIS database) - Has 1..n spatial contexts - [PostGIS Provider] It most likely infers this list from the spatial_ref_sys and geometry_columns metadata tables - Has 1..n feature classes - [PostGIS Provider] Any table that has a geometry/geography column - Each feature class has a designated logical geometry property - [PostGIS Provider] It probably either takes the first geometry/geography column or whatever is specified in geometry_columns - That geometry property has a spatial context of the chosen geometry property of the feature class it is referencing. - [PostGIS Provider] It probably either looks up geometry_columns or ST_SRID()'s the geometry/geography column so it knows what spatial_ref_sys table entry you are referring to. Now if you're wondering what is the purpose of a spatial context, it is primarily to determine the coordinate system of the originating layer. MapGuide uses spatial context information to determine if layers need on-the-fly feature re-projection when rendering maps. Hope that helps. - Jackie -- View this message in context: http://osgeo-org.1560.x6.nabble.com/Help-with-Spatial-Contexts-tp5310988p5311169.html Sent from the MapGuide Users mailing list archive at Nabble.com. _______________________________________________ mapguide-users mailing list mapguide-users@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/mapguide-users