MBTiles

Introduit dans la version 1.10: le pilote MBTiles permet de lire les rasters au format MBTiles, qui est une spécification pour stocker des données cartographique tuilées dans des bases de données SQLites.

GDAL/OGR doit être compilé avec la gestion du pilote SQLite, et des pilotes JPEG et PNG.

Le SRS esttoujours la projection Pseudo-Mercator (ie Google Mercator).

Le pilote peut récupéré les attributs des pixels encodés selon la spécification UTFGrid disponible dans certains fichiers MBTiles. Ils peuvent être obtenu avec la commande gdallocationinfo ou avec l’appel GetMetadataItem(“Pixel_iCol_iLine”, “LocationInfo”) sur un objet bande.

Exemples

• Accéder à un raster MBTiles distant :

  $ gdalinfo /vsicurl/http://a.tiles.mapbox.com/v3/kkaefer.iceland.mbtiles
  

  Renvoie :

  Driver: MBTiles/MBTiles
  Files: /vsicurl/http://a.tiles.mapbox.com/v3/kkaefer.iceland.mbtiles
  Size is 16384, 16384
  Coordinate System is:
  PROJCS["WGS 84 / Pseudo-Mercator",
      GEOGCS["WGS 84",
          DATUM["WGS_1984",
              SPHEROID["WGS 84",6378137,298.257223563,
                  AUTHORITY["EPSG","7030"]],
              AUTHORITY["EPSG","6326"]],
          PRIMEM["Greenwich",0,
              AUTHORITY["EPSG","8901"]],
          UNIT["degree",0.0174532925199433,
              AUTHORITY["EPSG","9122"]],
          AUTHORITY["EPSG","4326"]],
      PROJECTION["Mercator_1SP"],
      PARAMETER["central_meridian",0],
      PARAMETER["scale_factor",1],
      PARAMETER["false_easting",0],
      PARAMETER["false_northing",0],
      UNIT["metre",1,
          AUTHORITY["EPSG","9001"]],
      AXIS["X",EAST],
      AXIS["Y",NORTH],
      EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext  +no_defs"],
      AUTHORITY["EPSG","3857"]]
  Origin = (-3757031.250000000000000,11271093.750000000000000)
  Pixel Size = (152.873992919921875,-152.873992919921875)
  Image Structure Metadata:
    INTERLEAVE=PIXEL
  Corner Coordinates:
  Upper Left  (-3757031.250,11271093.750) ( 33d44'59.95"W, 70d36'45.36"N)
  Lower Left  (-3757031.250, 8766406.250) ( 33d44'59.95"W, 61d36'22.97"N)
  Upper Right (-1252343.750,11271093.750) ( 11d14'59.98"W, 70d36'45.36"N)
  Lower Right (-1252343.750, 8766406.250) ( 11d14'59.98"W, 61d36'22.97"N)
  Center      (-2504687.500,10018750.000) ( 22d29'59.97"W, 66d30'47.68"N)
  Band 1 Block=256x256 Type=Byte, ColorInterp=Red
    Overviews: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
    Mask Flags: PER_DATASET ALPHA
    Overviews of mask band: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
  Band 2 Block=256x256 Type=Byte, ColorInterp=Green
    Overviews: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
    Mask Flags: PER_DATASET ALPHA
    Overviews of mask band: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
  Band 3 Block=256x256 Type=Byte, ColorInterp=Blue
    Overviews: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
    Mask Flags: PER_DATASET ALPHA
    Overviews of mask band: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
  Band 4 Block=256x256 Type=Byte, ColorInterp=Alpha
    Overviews: 8192x8192, 4096x4096, 2048x2048, 1024x1024, 512x512
  

• Lire des attributs de pixel encodés selon la spécification UTFGrid :

  $ gdallocationinfo /vsicurl/http://a.tiles.mapbox.com/v3/mapbox.geography-class.mbtiles -wgs84 2 49 -b 1 -xml
  

  Renvoie :

  <Report pixel="33132" line="22506">
        <BandReport band="1">
          <LocationInfo>
            <Key>74</Key>
            <JSon>{"admin":"France","flag_png":"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"}</JSon>
          </LocationInfo>
          <Value>238</Value>
        </BandReport>
      </Report>
  

Voir aussi

• Spécification MBTiles
• Spécification UTFGrid