Re: Read sounding info of maps
You would have to load and parse all the charts that cover the area all the time. Quite a performance penalty involved, IMO.
Of course there could be plan B to extend the plugin API currently providing named chart objects to the API with sounding values and store them externally in an efficient, indexed way - Principally the same what Chart Object Search plugin does. Of course it works just after the chart is displayed once, but the subsequent performance hit is minimized.