MBTILES for opencpn

[ploubaz22]

Do you think that in future versions of opencpn the format of MBTILES cards is recognized

[bcn]

yes ...

[seandepagnier]

The future is now:

https://github.com/seandepagnier/mbtiles-nautical-tools

scripts can run on any OS, and convert mbtiles format into kap format which opencpn can read.




If you are looking for native mbtiles support in opencpn, we still have a few questions to answer because mbtiles contain possible transparency.



Should it calculate the quilted regions based on only the non-transparent part of the chart? This can be expensive. Or should we pre-process the non-transparent regions and describe them with a polygon with maximum number of points?


Furthermore, much mbtiles data is designed also to be blended, for example, satellite imagery on land with nautical chart in the sea. Many other possible combination exist. How do we handle the user interface for this? The standard chart piano is not sufficient unless we also add a slider to each key.

Consider cases like having 5 or 6 (or more) historical satellite images at various tide levels, and using blending to draw the tide moving in or out making it possible to predict where water is at any time in the future.

[rgleason]

Sean,
I do not know enough about mbtiles to answer your questions directly.
But I would like to ask a question about how this would affect weathfax_pi and if the mbtiles would have a transparency layer or not?

The reason I ask is weatherfax_pi actually depends on transparency to overlay, but kap does not have transparency as currently done in Opencpn.

But we all know that tiff does support a transparemcy layer, so presimably opencpn could too. That might make mbtiles more useful for weatherfax?
But would the transparent layer slow down Opencpn a lot?

It seems like mbtiles might be useful in weatherfax too particularly with the chart wizard tool.

Very interested in what you think.

Rick

[seandepagnier]

The weatherfaxes could be integrated as native charts.

The transparency doesn't slow things down much with opengl, but without opengl it will be a problem.

I'm not sure what the best solution for dealing with transparent charts in the user interface.