jmckenna at gatewaygeomatics.com
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GeoPackage, also written as “GPKG”, is a standards-based wrapper for the file-based SQLite database. GPKG is an encoding standard adopted by the Open Geospatial Consortium back in 2014, and has since gained popularity for distributing both vector & raster data, inside one compact file.
More information about GPKG is available at:
Similar to other database formats, the .gpkg file consists of several tables. The geometry is held in a BLOB table column.
Windows users who want to follow along, can convert MS4W’s included demo.db SpatiaLite database into a GPKG file (for the countries table) with the command (executed inside /ms4w/apps/local-demo/data/) :
ogr2ogr -f GPKG countries.gpkg demo.db countries
Data Access / Connection Method¶
GPKG access is available in MapServer through OGR’s GPKG driver. It is recommended to use GDAL/OGR version 2.2 or later for GPKG access.
OGR uses the names of spatial tables within the GPKG database (tables with a geometry column that are registered in the geometry_columns table) as layers.
The CONNECTION parameter must include the .gpkg extension, and the DATA parameter should be the name of the spatial table (or OGR layer).
CONNECTIONTYPE OGR CONNECTION "name.gpkg" DATA "layername"
The MapServer 7.4.x series contained a few critical fixes for GPKG access, therefore at the minimum, at least MapServer 7.6.0 is recommended.
Step 1: Use ogrinfo to examine¶
First you should make sure that your local GDAL/OGR build contains both the “GPKG” driver & the “SQLite / Spatialite” driver, by using the –formats command:
>ogrinfo --formats Supported Formats: ... GPKG -raster,vector- (rw+vs): GeoPackage SQLite -vector- (rw+v): SQLite / Spatialite ...
Once you have confirmed that you have the GPKG driver you are ready to try an ogrinfo command on your database to get a list of spatial tables:
>ogrinfo countries.gpkg INFO: Open of `countries.gpkg' using driver `GPKG' successful. 1: countries (Multi Polygon)
Now use ogrinfo to get information on the structure of the spatial ‘countries’ table:
>ogrinfo countries.gpkg countries -summary INFO: Open of `countries.gpkg' using driver `GPKG' successful. Layer name: countries Geometry: Multi Polygon Feature Count: 177 Extent: (-180.000000, -90.000000) - (180.000000, 83.645130) Layer SRS WKT: 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"]] FID Column = ogc_fid Geometry Column = GEOMETRY featurecla: String (0.0) scalerank: Integer (0.0) labelrank: Integer (0.0) sovereignt: String (0.0) sov_a3: String (0.0) adm0_dif: Integer (0.0) ...
Step 2: Add the layer in your mapfile¶
For OGR connections, it is always recommended to set CONNECTIONTYPE, CONNECTION, and DATA, as follows:
/* Countries */ LAYER NAME "countries" TYPE POLYGON STATUS ON CONNECTIONTYPE OGR CONNECTION "countries.gpkg" DATA "countries" # the OGR layername, found through ogrinfo CLASS NAME "World Countries" STYLE COLOR 200 200 200 OUTLINECOLOR 0 0 0 WIDTH 0.1 END #style END #class END #layer
Step 3: Test your Mapfile with shp2img¶
Use the MapServer commandline utility shp2img to verify that your mapfile creates a valid map image, and also display draw times, such as:
shp2img -m geopackage.map -o ttt.png -map_debug 3 msDrawMap(): rendering using outputformat named png (AGG/PNG). msDrawMap(): WMS/WFS set-up and query, 0.000s msDrawMap(): Layer 0 (countries), 0.078s msDrawMap(): Drawing Label Cache, 0.000s msDrawMap() total time: 0.079s msSaveImage(ttt.png) total time: 0.008s