4.9.3. Export command¶

Synopsis

impexp export [-hV] [--[no-]fail-fast] [--replace-ids]
              [--ade-extensions=<folder>] [-c=<file>]
              [--compressed-format=<format>] [--id-prefix=<prefix>]
              [--log-file=<file>] [--log-level=<level>] -o=<file>
              [--output-encoding=<encoding>] [--pid-file=<file>]
              [--plugins=<folder>] [--use-plugin=<plugin[=true|false]>[,
              <plugin[=true|false]>...]]... [--worker-threads=<threads[,
              max]>] [[[-t=<[prefix:]name>[,<[prefix:]name>...]]...
              [--namespace=<prefix=name>[,<prefix=name>...]]...]
              [[-r=<version>] [-R=<timestamp[,timestamp]>]] [-i=<id>[,
              <id>...] [-i=<id>[,<id>...]]...] [--db-id=<id>[,<id>...]
              [--db-id=<id>[,<id>...]]...] [-b=<minx,miny,maxx,maxy[,
              srid]> [--bbox-mode=<mode>] [-g=<rows,columns>]]
              [[--count=<count>] [--start-index=<index>]] [-l=<0..4>[,
              <0..4>...] [-l=<0..4>[,<0..4>...]]... [--lod-mode=<mode>]
              [--lod-search-depth=<0..n|all>]] [[--no-appearance] |
              -a=<theme>[,<theme>...] [-a=<theme>[,<theme>...]]...]
              [-s=<select>] [-q=<xml>]] [[-T=<database>] [-H=<host>]
              [-P=<port>] [-d=<name>] [-S=<schema>] [-u=<name>] [-p
              [=<password>]]] [@<filename>...]

Description

The export command exports top-level city objects from the 3D City Database in CityGML or CityJSON format. It corresponds to the export operation offered on the Export tab of the graphical user interface (see Section 4.5). The command provides a range of options to adapt the export process. If you miss settings available for the GUI version of this command, you can use the --config option to pass a config file containing these settings.

General options

-o, --output=<file>¶: Specify the output file to use for storing the exported city objects. By default, CityGML is used as output format. The output format can be changed to CityJSON by choosing .json or .cityjson as file extension. Moreover, compressed exports using GZIP (.gz, .gzip) or ZIP (*.zip) are possible. The supported formats and file extensions are also listed in Table 4.18.

--output-encoding=<encoding>¶: Define the encoding of the output file using a IANA-based character encoding name. The default value is UTF-8.

--compressed-format=<format>¶: For compressed exports using GZIP or ZIP, specify the output format to use for encoding the data. Allowed values are citygml and cityjson.

--replace-ids¶: Replace all identifiers of features and geometries with UUID values (default: false).

--id-prefix=<prefix>¶: The prefix to use for UUID values when replacing object identifiers (default: ID_).

--[no-]fail-fast¶: Flag to indicate whether to fail fast on errors and to immediately cancel the export process (default: true).

--worker-threads=<threads[,max]>¶: Number of parallel threads to use for the export process. You can also specify a minimum and maximum number of threads separated by commas. A general description of the multithreaded processing used for the export process is provided in Section 4.5.9.12.

Query and filter options

The export command offers additional options to define both thematic and spatial filters that are used to restrict the export to a subset of the top-level city objects stored in the 3D City Database.

-t, --type-name=<[prefix:]name>[,<[prefix:]name>...]¶: Comma-separated list of one or more names of the top-level feature types to be exported. The type names are case sensitive and shall match one of the official CityGML feature type names or a feature type name from a CityGML ADE. To avoid ambiguities, you can use an optional prefix for each name. The prefix must be associated with the official XML namespace of the feature type. You can either use the official CityGML namespace prefixes listed in Table 4.11. Or you can use the --namespace option to declare your own prefixes.

--namespace=<prefix=name>[,<prefix=name>...]¶: Used to specify namespaces and their prefixes as comma-separated list of one or more prefix=name pairs. The prefixes can be used in other options such as --type-name.

-r, --feature-version=<version>¶: Specify the version of the top-level features to use for the export. Allowed values are latest, at, between, terminated, terminated_at and all. When choosing latest, only those features that have not been terminated in the database are exported, whereas all will export all features. You can also choose to export only features that were valid at a given timestamp using at or for a given time range using between. Likewise, terminated will return all terminated features whereas terminated_at will select features that were terminated at a given timestamp. In all cases, timestamps must be provided using the --feature-version-timestamp option. Further details about the feature version filter are available in Section 4.5.1.

-R, --feature-version-timestamp=<timestamp[,timestamp]>¶: One or two timestamps to be used with the --feature-version option. A timestamp can be given as date in the form YYYY-MM-DD or as date-time specified as YYYY-MM-DDThh:mm:ss[(+|-)hh:mm. The date-time format supports an optional UTC offset. Use one timestamp with the at and terminated_at values and two timestamps separated by comma with the between value of the --feature-version option.

-i, --resource-id=<id>[,<id>...]¶: Comma-separated list of one or more identifiers. Only top-level features having a matching value for their identifier attribute will be exported.

--db-id=<id>[,<id>...]¶: Comma-separated list of one or more database IDs. Only top-level features having a matching primary key for the ID column of the CITYOBJECT table will be exported.

-b, --bbox=<minx,miny,maxx,maxy[,srid]>¶: 2D bounding box to use as spatial filter. The bounding box is given by four coordinates that define its lower left and upper right corner. By default, the coordinates are assumed to be in the same CRS that is used by the 3DCityDB instance. Alternatively, you can provide the database srid of the CRS associated with the coordinates as fifth value (e.g. 4326 for WGS84). All values must be separated by commas. The bounding box is evaluated against the GMLID column of the CITYOBJECT table.

--bbox-mode=<mode>¶: Choose the mode of the bounding box filter. Allowed values are overlaps (default) and within. When set to overlaps, all features overlapping with the bounding box are exported. Otherwise, features must be within the given bounding box. Can only be used together with the --bbox option.

-g, --bbox-tiling=<rows,columns>¶: Use this option to enable tiling for the export. The bounding box given by the --bbox option is split into a regular grid having the specified number of rows and columns. Each grid cell is exported as separate tile. The values for rows and columns must be separated by a comma. More information about tiled exports is provided in Section 4.5.

--count=<count>¶: Maximum number of top-level features to be exported.

--start-index=<index>¶: Index within the result set of all top-level features from which the export shall begin. The start index uses zero-based numbering. Thus, the first top-level feature is assigned the index 0, rather than the index 1.

-l, --lod=<0..4>[,<0..4>...]¶: Comma-separated list of LoDs that shall be exported for the city objects. Each LoD value must be given as integer between 0 and 4. If you provide more than one LoD, use the --lod-mode option to specify how the values shall be evaluated. LoD representations of a city object that are stored in the database but not listed with this option are not exported. See Section 4.5.4 for more details.

--lod-mode=<mode>¶: Specify the LoD filter mode in case you have provided more than one LoD value for the --lod option. Allowed values are or (default), and, minimum, and maximum. When choosing or, a city object must have a spatial representation in at least one of the given LoDs to be exported, whereas and requires a representation in all LoDs. Both minimum and maximum are special versions of or where only the lowest or highest LoD representation from the matching ones is exported.

--lod-search-depth=<0..n|all>¶: Number of levels of nested city objects that shall be considered by the LoD filter when searching for a matching LoD representation (see also Section 4.5.4). Either provide a non-negative integer or all as value. The default value is 1.

--no-appearance¶: Flag to indicate that appearances of the features shall not be exported.

-a, --appearance-theme=<theme>[,<theme>...]¶: Comma-separated list of appearance themes. Only appearances having a matching theme will be exported. Use none as value to address appearance features lacking a theme attribute.

-s, --sql-select=<select>¶: Provide an SQL SELECT statement to be used as SQL filter when querying the database. In general, any SELECT statement can be used as long as it returns a list of database IDs of the selected city objects (see Section 4.5.3 for more information). You can also use an @-file to provide the SELECT statement (see Section 4.9.9.3).

-q, --xml-query=<xml>¶: This option allows you to use a full-fledged XML query expression as filter for the export operation. Make sure the query expression is valid and adheres to the specification for XML query expressions provided in Section 4.5.8. You can also use an @-file to provide the query expression (see Section 4.9.9.3). This option cannot be used with any other filter option of the export command.

Database connection options

The following options allow you to define the connection details that shall be used for establishing a connection to the 3D City Database. You can also use environment variables for this purpose (see Section 4.9.8).

-T, --db-type=<database>¶: Specify the database system used for running the 3DCityDB. Allowed values are postgresql for PostgreSQL/PostGIS databases (default), and oracle for Oracle Spatial/Locator databases.

-H, --db-host=<host>¶: Specify the host name of the machine on which the 3DCityDB database server is running.

-P, --db-port=<port>¶: Specify the TCP port on which the 3DCityDB database server is listening for connections. The default value is 5432 for PostgreSQL and 1521 for Oracle.

-d, --db-name=<name>¶: Specify the name of the 3DCityDB database to connect to. When connecting to an Oracle database, provide the database SID or service name as value.

-S, --db-schema=<schema>¶: Name of the database schema to use when connecting to the 3DCityDB. If not provided, the citydb schema is used for PostgreSQL by default, whereas the schema of the user specified by the option --db-username is used under Oracle.

-u, --db-username=<name>¶: Connect to the 3DCityDB database server as the user given by name.

-p, --db-password[=<password>]¶: Specify the password to use when connecting to the 3DCityDB database server. You can either provide the password as value for this option or leave the value empty to be prompted to enter the password on the console before connecting to the database. If you skip this option completely, the impexp tool will try to connect to the database without a password. If the database server requires password authentication and a password is not available by other means, the connection attempt will fail in this case.

Examples

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password -o my_city.gml

Export the entire database content as CityGML to the output file my_city.gml. The 3DCityDB to connect to is supposed to be running on a PostgreSQL database on the same machine. The connection will be established to the citydb_v4 database with the user citydb_user and the password my_password.

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password \
                -t Building -b 13.3508824,52.4799281,13.3578297,52.4862805,4326 \
                -o my_city.json

Only export Building features overlapping with the provided bounding box from the database. The coordinates of the bounding box are given in WGS84. For this reason, the fifth value 4326 of the -b option denotes the SRID that is used by the target database for the WGS84 reference system. The output format is CityJSON.

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password \
                -i ID_0815,ID_0816 -l 1,2,3 --lod-mode=maximum
                --compressed-format=citygml -o my_city.zip

Export the top-level city objects with the identifiers ID_0815 and ID_0816 from the database if they have an LoD representation in either LoD 1, 2 or 3. From the matching LoD representations, only export the highest LoD. The output file will be a compressed ZIP archive containing a CityGML file with the exported city objects.

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password \
                -s "select cityobject_id from cityobject_genericattrib \
                    where attrname='energy_level' and realval < 12" \
                -o my_city.zip

Export all city objects satisfying the given SQL SELECT statement.

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password \
                -s "select cityobject_id from cityobject_genericattrib \
                    where attrname='energy_level' and realval < 12" \
                -o my_city.zip

Export all city objects satisfying the given SQL SELECT statement.

$ impexp export -H localhost -d citydb_v4 -u citydb_user -p my_password \
                @/path/to/xml-query -o my_city.gml

Export all city objects satisfying the given XML query expression. To avoid possible system limitations on the length of the command line, the XML query is stored in a separate argument file called xml-query which is referenced from the command line using the @-file notation. The content of the xml-query file is shown below:

-q
'<query xmlns="http://www.3dcitydb.org/importer-exporter/config"> \
  <typeNames> \
    <typeName xmlns:bldg="http://www.opengis.net/citygml/building/2.0">bldg:Building</typeName> \
  </typeNames> \
  <filter> \
    <bbox> \
      <envelope srid="4326"> \
        <lowerCorner>13.3508824 52.4799281</lowerCorner> \
        <upperCorner>13.3578297 52.4862805</upperCorner> \
      </envelope> \
    </bbox> \
  </filter> \
  <sortBy> \
    <sortProperty> \
      <valueReference>bldg:measuredHeight</valueReference> \
    </sortProperty> \
  </sortBy> \
  <limit> \
    <count>20</count> \
  </limit> \
</query>'

According to this query expression, only the first 20 buildings satisfying the provided bounding box filter and sorted by their bldg:measuredHeight attribute will be exported.

Note

For the above @-file xml-query to work, the following requirements must be met:

The entire XML query expression is the value of the -q option and, thus, must be put on a single line in the argument file. Either avoid line breaks in your XML or escape them using a backslash \ character like in the above example.
Since the XML query expression contains whitespace, it must be put in double or single quotes. When using double quotes, all double quotes of the query expression itself must be escaped. To avoid escaping, the above example uses single quotes.