2020-01-13, 09:12 PM
Since we are on this topic, a few tips for creating mbtiles charts from SASPlanet:
1. (and this is a big one) Don't choose every zoom. Zoom 1 is like a hemisphere, and Zoom 24 is grains of sand on the beach (I'm exaggerating, but you get the idea). Try starting at something like Zoom 6 or 8, and going down to around 18, choosing only every other zoom (6, 8, 10, 12, etc...). OpenCPN will scale between the zooms, and beyond about 18 you aren't getting enough additional detail to be worth the download time.
2. Preload you cache. Use the selection tool to choose the area you are going to make charts of, and the zoom levels, then tell SASPlanet to download those tiles. Save the selection area so you can use it again. When you go to export to mbtiles, just choose the same selection area and ask for an mbtiles chart to be made, using the same zoom levels you originally preloaded into your cache.
3. Use the polygon selection tool instead of the rectangular tool. That way you don't end up downloading and making charts of large areas of land that you don't care about.
All of this will cut your download time from days to hours.
1. (and this is a big one) Don't choose every zoom. Zoom 1 is like a hemisphere, and Zoom 24 is grains of sand on the beach (I'm exaggerating, but you get the idea). Try starting at something like Zoom 6 or 8, and going down to around 18, choosing only every other zoom (6, 8, 10, 12, etc...). OpenCPN will scale between the zooms, and beyond about 18 you aren't getting enough additional detail to be worth the download time.
2. Preload you cache. Use the selection tool to choose the area you are going to make charts of, and the zoom levels, then tell SASPlanet to download those tiles. Save the selection area so you can use it again. When you go to export to mbtiles, just choose the same selection area and ask for an mbtiles chart to be made, using the same zoom levels you originally preloaded into your cache.
3. Use the polygon selection tool instead of the rectangular tool. That way you don't end up downloading and making charts of large areas of land that you don't care about.
All of this will cut your download time from days to hours.