"No data" error while loading custom .mbtiles file

Question

I'm using Nutiteq SDK to develop an Android map app that needs to work offline and display a map of a small city, so im working with .mbtiles file. So far, an .mbtile file downloaded using TileMill worked great, or rather one of their demo projects, because Internet access is sometimes a big problem for me, for that same reason, it sounded great when a friend of mine told me he wrote a Python script to create an .mbtiles file from a tiles .png folder, with the exact .mbtiles format. I tried using a file obtained this way and i get the following error when loading files:

10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=277 y=444
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=278 y=444
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=277 y=443
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=278 y=443
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=277 y=445
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer: Start loading  zoom=10 x=278 y=445
10-02 00:11:41.976: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=277        y=444
10-02 00:11:42.340: DEBUG/TileDatabaseHelper(404): not found z=10 x=277 y=579
10-02 00:11:42.340: ERROR/hellomap(404):      com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:42.536: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=278 y=444
10-02 00:11:42.636: DEBUG/TileDatabaseHelper(404): not found z=10 x=278 y=579
10-02 00:11:42.636: ERROR/hellomap(404):     com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:42.746: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=277 y=443
10-02 00:11:42.746: DEBUG/TileDatabaseHelper(404): not found z=10 x=277 y=580
10-02 00:11:42.746: ERROR/hellomap(404): com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:42.947: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=278 y=443
10-02 00:11:43.186: DEBUG/hellomap(404): onDrawFrame: Last frame time 325ms
10-02 00:11:43.346: DEBUG/TileDatabaseHelper(404): not found z=10 x=278 y=580
10-02 00:11:43.360: ERROR/hellomap(404): com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:43.360: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=277 y=445
10-02 00:11:43.596: DEBUG/hellomap(404): onDrawFrame: Last frame time 230ms
10-02 00:11:43.706: DEBUG/TileDatabaseHelper(404): not found z=10 x=277 y=578
10-02 00:11:43.706: ERROR/hellomap(404): com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:43.706: DEBUG/hellomap(404): DbMapLayer task: Start loading  zoom=10 x=278 y=445
10-02 00:11:43.706: DEBUG/TileDatabaseHelper(404): not found z=10 x=278 y=578
10-02 00:11:43.706: ERROR/hellomap(404): com.nutiteq.layers.raster.MBTilesMapLayer$DbFetchTileTask: No data.
10-02 00:11:43.966: DEBUG/hellomap(404): onDrawFrame: Last frame time 249ms

I'm guessing something wrong with the script, but the fact is he is using the same .mbtiles file with the MapBox iOS SDK without problem.

I was hoping someone who has worked with maps, preferably with MBTiles and/or Nutiteq can give some insight.

Thanks.

Answer 1

From the log it seems that the requested map tiles are just missing from the database. You can check it with

sqlite3 <file>.mbtiles
sqlite> select * from tiles where zoom_level=10 and tile_column=277 and tile_row=579;

If this returns empty data, then the data is not there. If it returns a line, then check that the file was opened properly.

There is also possibility that y is flipped, as TMS has different origin than common web map tiles (like OSM). You can change this in application, MBTilesLayer has setTmsY(), try to set it true.