Extract a geospatial database from a MapsForge map
map2db is a python 3 module which creates an FDO RFC 16 conforming sqlite geospatial database from the contents of a mapsforge format map created by forgemap with the dbl option.
This allows a map created from a derivative database of a database licensed under the Open Data Commons Open Database License (ODbL) v1.0 <https://opendatacommons.org/licenses/odbl/1-0> to satisfy the "Share alike" conditions of use described in section 4.6 of that license by simply providing a link to this tool.
If you have received a copy of a mapsforge format map with a link to this page, It may be have been created from a derivative database of a database licensed under ODbL v1.0. If so, the creator of such a map is required to offer you a copy in machine readable form of the entire derivative database that was used to create the map. map2db allows you to extract that derivative database from the map file that you already have, thereby satisfying this requirement. Note that section 4.6b allows that an algorithm may have to be applied to reconstruct the derivative database. map2db is the implementation of such an algorithm.
The license statement encoded in the map file for the recreated database is both written to the README table of the database and printed. The creator of the map file is responsible for ensuring that this statement defines the license under which the database is released, or the lack thereof, and that it satisfies any licencing requirements imposed by the data used to create the database.
A TOML configuration file suitable for building a new mapsforge map with the dbl option from the recreated database using forgemap is also produced.
If map2db is applied to any mapsforge map that was created by any program other than forgemap or which was created by forgemap, but without the dbl option, then a database can usually still be created from it. However, this database will contain the raw content of every tile in the map rather than a properly reconstructed database with various parts of each feature merged together and more simplified versions of such features discarded in favor of the less simplified versions. The dbl option of forgemap also explicitly encodes whether the source geometry was a line or area feature. Since this information is not available, those way features in which every coordinate block forms a closed ring with at least four points are assumed to be areas, while the remainder are assumed to be lines. This may misclassify some features as areas that should have been lines. Since not all closed rings of at least four points are valid, this may produce unexpected results. When used with such a map, a brief message explaining this is both written to the README table of the database and printed in place of a license statement. Since no database license statement is encoded in such a map file, the user is responsible for determining what legal restrictions apply to use of the recreated database.
map2db requires shapely version >= 2.0
Usage:
>>> from map2db import map2db >>> map2db(src_pathname, dst_pathname)
or
$ python3 map2db.py src_pathname dst_pathname
From the command line, if dst_pathname is not provided, then one is derived from src_pathname.