Chart depths - units - plugin API

[Rasbats]

Need to access the depth units (feet, metre etc) for the chart in use.

Is this possible? Or do the functions in the API only apply to a chart opened by the plugin?

This is for work on Survey_pi.

Mike

[nohal]

Mike, it is more complicated than it seems as charts with completely different units can be displayed in a quilt.
For vector charts on the other hand the depth unit is selected by the user and does not depend on the charts at all.

[Rasbats]

Thanks Pavel ...

That will save a lot of head banging.

Mike

[ian5142]

What about this?
virtual wxString GetDepthUnits() { return m_DepthUnits;}


from ocpn_plugin.h


What does it return?

[nohal]

That is an API of plugins implementing charts, like S63, oeSENC and oeRNC. It tells the core what depth units a chart provided by the plugin uses. = It does pretty much exactly the opposite of what Mike would want. What Mike wants is not practically possible in all but special cases where all the displayed charts use the same units.

[ian5142]

OK, so not that setting.


I am trying to retrieve this setting, from the screenshot.

[nohal]

PI_GetPLIBDepthUnitInt() will give you the depth units used by the S52 presentation library.

[ian5142]

What is the disadvantage to using that instead of creating a separate setting?

[nohal]

I'm afraid I don't understand, what does "creating a separate setting" mean exactly?

[ian5142]

Currently the survey_pi plugin has its own depth setting in its plugin preferences. This is of course independent of the rest of OpenCPN.

[Rasbats]

Ian ...

I think the real problem is the lack of units in the schema for the soundings table. At the moment we plot what NMEA is feeding the plugin and do not record the units. The workaround is that preferences are used to adjust for the display of the depth in the units you want but it does not change the sounding recorded in the table. Need to add a column for the units in use and display that in the plugin dialog.

Mike

[ian5142]

I thought of another workaround without adding a new column to the table / database. What about just adding an import only setting that is accessible in the import dialog window?


NMEA streams themselves default to meters. https://gpsd.gitlab.io/gpsd/NMEA.htm...depth_of_water Assume all values in the table are meters and convert to anything else.

[Rasbats]

That's a better idea. What is your source for depths non-metric? Is this a real-world problem? Or is it just to enable the correct display on the chart?

[ian5142]

My source for non-metric depths. My equipment all conforms to NMEA standards and outputs DPT sentences in meters. The only problem is if somebody imports something using the import dialog that is in feet or fathoms. I have no idea where this will come from.



I still have an end goal to display the data on the chart overlay in the same measurement as the chart (from the setting mentioned earlier).

[bcn]

Ideally you would generate a S-57 overlay chart. OpenCPN would take care about the units for presentation then.