QGIS Tutorial – How to Use Natural Earth SQLite DB with QGIS

natural-earthqgisspatialitesqlite

I just downloaded the Natural Earth data in SQLite format from http://www.naturalearthdata.com/downloads/. I had assumed that this would be a SpatiaLite database, but it appears not to be! QGIS is failing to recognize it as a spatial database. OGR supposedly supports reading geometries even when stored in a plain SQLite database, but maybe QGIS doesn't use OGR for SpatiaLite?

The SQLite database does have geometry_columns and spatial_ref_sys tables. Is there some way to convert it to a full SpatiaLite database?

Best Answer

The sqlite file from NE is in FDO-OGR format, not the native spatialite geometry. If you're willing to do some manual labor, here's a way to convert to a spatialite db:

First make a new, empty spatialite database (I call it "nev.sqlite"), then in a separate terminal session open the original natural_earth_vector.sqlite with spatialite. (I used the newer version 4.1. Not sure if this will work with the older versions). Use the sqlite attach function to connect to your new nev.sqlite table, and create copies of the tables you want into the new database.

So:

micha@Wheezy:~$ spatialite natural_earth_vector.sqlite 
SpatiaLite version ..: 3.0.0-beta   Supported Extensions:
    - 'VirtualShape'    [direct Shapefile access]
    - 'VirtualDbf'      [direct DBF access]
    - 'VirtualXL'       [direct XLS access]
    - 'VirtualText'     [direct CSV/TXT access]
    - 'VirtualNetwork'  [Dijkstra shortest path]
    - 'RTree'       [Spatial Index - R*Tree]
    - 'MbrCache'        [Spatial Index - MBR cache]
    - 'VirtualSpatialIndex' [R*Tree metahandler]
    - 'VirtualFDO'      [FDO-OGR interoperability]
    - 'SpatiaLite'      [Spatial SQL - OGC]
PROJ.4 version ......: Rel. 4.7.1, 23 September 2009
GEOS version ........: 3.3.3-CAPI-1.7.4
SQLite version ......: 3.7.13

================ FDO-OGR Spatial Metadata detected ===============
.....
    created VirtualFDO table 'fdo_ne_110m_geography_regions_points'
    created VirtualFDO table 'fdo_ne_110m_geography_regions_polys'
    created VirtualFDO table 'fdo_ne_110m_glaciated_areas'
    created VirtualFDO table 'fdo_ne_110m_lakes'
    created VirtualFDO table 'fdo_ne_110m_land'
    created VirtualFDO table 'fdo_ne_110m_ocean'
    created VirtualFDO table 'fdo_ne_110m_rivers_lake_centerlines'
Accessing these fdo_XX tables you can take full advantage of
FDO-OGR auto-wrapping facility
This allows you to access any specific FDO-OGR Geometry as if it
where native SpatiaLite ones in a completely transparent way
==================================================================

Enter ".help" for instructions
spatialite> attach "nev.sqlite" AS nev;
spatialite> 
spatialite> CREATE TABLE nev.countries AS SELECT * from fdo_ne_10m_admin_0_countries;
spatialite> CREATE TABLE nev.populated_places AS SELECT * FROM fdo_ne_10m_populated_places;
spatialite> CREATE TABLE nev.railroads AS SELECT * FROM fdo_ne_10m_railroads;
spatialite> .q

*** FDO-OGR auto-wrapping shutdown done ***

All the lines "created VirtualFDO..." indicate that Spatialite recognized the data as FDO formated, and created virtual tables for each with the GEOMETRY converted to spatialite format. I attach to my new "nev" database and create new tables for each layer I'm interested in with the CREATE TABLE ... AS SELECT * FROM ... statements.

Now I switch back over the the new spatialite database. And run RecoverGeometryColumn() on each table to get a proper spatialite database, with all metadata, etc. Note that the FDO format allows for mixed MULTI and SINGLE geometry types, so I first check which geometry types each table contains, and make sure that all features are the same. I use CastToMulti() wherever necessary, like so:

micha@Wheezy:~/GIS/World/naturalearthdata.com$ spatialite nev.sqlite
SpatiaLite version ..: 4.1.1    Supported Extensions:
    - 'VirtualShape'    [direct Shapefile access]
    - 'VirtualDbf'      [direct DBF access]
    - 'VirtualXL'       [direct XLS access]
    - 'VirtualText'     [direct CSV/TXT access]
    - 'VirtualNetwork'  [Dijkstra shortest path]
    - 'RTree'       [Spatial Index - R*Tree]
    - 'MbrCache'        [Spatial Index - MBR cache]
    - 'VirtualSpatialIndex' [R*Tree metahandler]
    - 'VirtualFDO'      [FDO-OGR interoperability]
    - 'SpatiaLite'      [Spatial SQL - OGC]
PROJ.4 version ......: Rel. 4.7.1, 23 September 2009
GEOS version ........: 3.3.3-CAPI-1.7.4
SQLite version ......: 3.7.13
Enter ".help" for instructions
SQLite version 3.7.13 2012-06-11 02:05:22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
spatialite> .tables
SpatialIndex            geometry_columns_auth   spatialite_history    
countries               populated_places        sql_statements_log    
geom_cols_ref_sys       railroads               views_geometry_columns
geometry_columns        spatial_ref_sys         virts_geometry_columns
spatialite> 
spatialite> SELECT GeometryType(GEOMETRY) FROM countries;
POLYGON
POLYGON
MULTIPOLYGON
MULTIPOLYGON
POLYGON
MULTIPOLYGON
POLYGON
MULTIPOLYGON
MULTIPOLYGON
.....

Geometries are mixed, so set everything MULTI, then do RecoverGeometryColumn():

spatialite> UPDATE countries SET GEOMETRY=CastToMulti(GEOMETRY);
spatialite> SELECT RecoverGeometryColumn('countries','GEOMETRY',4326,'MULTIPOLYGON',2);
1
spatialite>

And so on for each table you need. Now the tables are available in QGIS.

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