Map loaded, but no data shown

[pgrawehr]

I tried using the "Europe" map from https://downloadlayer--onlinechart-ol3.netlify.com/#/download/%5Embtile%24/-719043247?lat=49.1602&lon=10.6979&zoom=5&layers=A1-1&lang=de with this plugin, but it just doesn't work as expected.

• I specify the directory where it's located in the plugin config (/home/pi/Charts/Mbtiles in my case)
• Server restarted (in interactive mode). It shows that it found one map in the given directory
• Open the freeboard-sk map viewer, the chart list shows the newly configured map
• Now I uncheck all the other (online) maps

Nothing is visible, despite the fact that I'm sure that I'm within the map range. The map does work in OpenCPN.

The server log contains messages of the form

GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1079/653 404 4.241 ms - 9
GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1082/655 404 47.244 ms - 9
GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1082/654 404 48.138 ms - 9
GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1082/653 404 46.008 ms - 9
GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1083/655 404 42.510 ms - 9
GET /signalk/v1/api/resources/charts/Europa1-20190621/11/1083/654 404 33.684 ms - 9

So the map server doesn't find the map it's supposed to have (or cannot properly decode the cell indices)

The world coastline map does work as expected.

[tkurki]

For one thing that file has odd min and maxzoom settings:

    "OSM-OpenCPN2-Europa1-20190621-0730": {
        "identifier": "OSM-OpenCPN2-Europa1-20190621-0730",
        "name": "Europa1",
        "bounds": [
            4.405517578125,
            43.45291889355465,
            16.995849609375,
            54.32613472050531
        ],
        "minzoom": 16,
        "maxzoom": 16,
        "format": "png",
        "type": "tilelayer",
        "tilemapUrl": "/signalk/v1/api/resources/charts/OSM-OpenCPN2-Europa1-20190621-0730/{z}/{x}/{y}",
        "scale": "250000"
    },

[tkurki]

There is only one zoom level in the file:

sqlite> select distinct zoom_level from tiles;
16

and if you zoom in to that level there is detail there, here shown Zellsee by RadolfZell

Where did these files come from? The Baltic file has more zoom levels available:

k$ echo "select distinct zoom_level from tiles" | sqlite3  OSM-OpenCPN2-Baltic-20190618-1343.mbtiles
8
10
12
14
16

[pgrawehr]

Oh... It seems I never hit exactly that zoom level. But that explains the problems, and is also consistent with the finding that the KAP file (the other format for the same region on that website) has the same behavior of only consisting of one level. It seems I need to find out how to request an update of the map files.

I found that MOBAC (https://mobac.sourceforge.io/) can create the correct maps (when feed with updated tile sources), but I would prefer not to do that myself, because it requires downloading a huge number of tiles for decently sized maps, which is "discouraged" by the server usage policies.