VFK - Czech Cadastral Exchange Data Format
This driver reads VFK files, ie. data in the Czech cadastral
exchange data format. The VFK file is recognized as an OGR
datasource with zero or more OGR layers. The filenames must end with
Note: starting with OGR 1.10, the driver is compiled only if GDAL
is built with SQLite support.
Points are represented as wkbPoints, lines and boundaries as
wkbLineStrings and areas as wkbPolygons. wkbMulti* primitives are not
used. Feature types cannot be mixed in one layer.
Starting with OGR 1.9, the driver reads and writes VFK data from/to
internal SQLite database. Default name of the database is
"<input_vfk_file>.db". Since OGR 1.10, you can define
an alternative DB name with OGR_VFK_DB_NAME configuration
option. If OGR_VFK_DB_OVERWRITE=YES configuration option is
given, than the driver overwrites existing SQLite database and reads
data from original input VFK file. By default, the internal SQLite
database is not automatically deleted. Since OGR 1.11, the internal
database is deleted if OGR_VFK_DB_DELETE=YES configuration
option is given.
Starting with OGR 1.10, resolved geometries are stored also in SQLite
database. It means that geometries are resolved only once when
building SQLite database from original VFK data. Geometries are stored
in WKB format. Note that GDAL doesn't need to be built with SpatiaLite
support. Geometries are not stored in DB
when OGR_VFK_DB_SPATIAL=NO configuration option is given. In
this case the geometries are resolved from DB.
Internal working and performance tweaking
Since OGR 1.9, the driver uses an internal SQLite database to resolve
geometries. By default, this file will be written in the same
directory as input VFK file. If SQLite database already exists then
the driver reads VFK features directly from the database (and not from
original VFK file).
Since OGR 1.11, the driver reads by default all data blocks. When
configuration option OGR_VFK_DB_READ_ALL_BLOCKS=NO is given
than the driver reads only data blocks which are requested by the
Datasource name is a full path to the VFK file.
VFK data blocks are used as layer names.
OGR internal SQL engine is used to evaluate the expression. Evaluation
is done once when the attribute filter is set.
Bounding boxes of features stored in topology structure are used to
evaluate if a features matches current spatial filter. Evaluation is
done once when the spatial filter is set.