Read sounding info of maps

[danics]

hi everybody,

I want to create a plugin for reading available sounding info under ownship or mouse position (or nearest) in any scale, I mean maybe Map be in a large scale and so i must load a smaller scale without showing in viewport and get soundg information.

i want to know whats the proper way of writing this plugin?

thanks a lot.

[seandepagnier]

To get from raster charts is difficult and error prone.

For vector charts.. it is a feature currently not implemented. It would be nice.

[danics]

Yes, i want to this on cm93 or s57 charts

If map scale be in a right scale I can read the SOUNDG feature for cm93 charts but how can I read another chart scale's features without rendering it in Viewport?

thanks in advance

[nohal]

danics...
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.

Pavel

[danics]

it is a good idea, I look at it too thanks a lot.

Boat speed is slow enough for query this info from another thread and after all i don't think we need all chart scale's object data. just 3 or 4 must be enough and one part I don't understand completely is that witch ViewPort size and scale should i use for reading these info from different charts?, I mean a ViewPort With size 100x100 and center of boat position don't load correctly needed map (i use SetVPparams) ?
do you have any idea how can i use right values for scale and viewport size?

[nohal]

danics...
Why do you want the viewport and scale at all? Especially when you want to work with the data from charts not being displayed at all... I suppose you are interested in the boat/cursor lat/long and the sounding closest to it, aren't you?
The discussion would probably be a bit more productive looking at some code on Github.

Pavel