I have some success with two basic scripts I have written to put tiled data into opencpn
. There are many tiled data available via the web such as osm, google earth
, topographic data etc.. If you have used sas planet you can see quite a list of sources.
The first script extracts the coordinates of all of the cm93 tiles into a seed yaml file. mapproxy-seed pulls the tiled data into an mbtiles file with worldwide coverage and good scale without running out of storage
, and with reasonable bandwidth. I realize this has limitations as cm93 doesn't cover a lot of areas with good detail, but it's a starting point and covers a large amount of harbors and difficult passes. It's easily possible to add additional coordinates as needed in the future to expand the database.
Making mbtiles a native format in opencpn
is a goal of mine, but in the meantime I wrote another script which converts this single
mbtiles file into thousands of kap files.
The results are very good initially and there are various minor improvements to make.
I can for example pull google
imagery, In fact the current
ge2kap which by comparison is not as user friendly (mine can work on any os and just needs an input of bounding boxes, contours or shapefiles to define the areas to scan)
But there is a pressing issue. I know on many sail blogs etc, you can download google
imagery kap files. At least, it is ok for a single
user to pull but according to google, it is a violation of their tos to redistribute imagery.
Furthermore I would apply various filters to the imagery especially to improve contrast over water
, and possibly to reduce detail over land to save disk space.