ohdm2mapnik

Ohdm2mapnik (deprecated)

Use OSMImportUpdate

The following command will receive no additional support anymore, please use OSMImportUpdate instead!

Intro

ohdm2mapnik convert a OHDM (Open Historical Data Map) database schema to a mapnik readable Osm2pgsql schema.

Database setup

This project does not contain an option to create a time sensitive OSM database.
For this purpose use [https://github.com/OpenHistoricalDataMap/OSMImportUpdate](https://github.com/OpenHistoricalDataMap/OSMImportUpdate)!

For this command a OHDM database connection is need to set up in .envs/.local/.postgres for the developing instance and for production is it .envs/.production/.postgres.

An example will look like::

# OHDM PostgreSQL
# ------------------------------------------------------------------------------
OHDM_SCHEMA=ohdm

Theory

For converting the database from OHDM schema to Osm2pgsql (mapnik readable) schema, the command will create an SQL statement, which will merge multiple OHDM tables into one output.

The tables are classification, geoobject, geoobject_geometry and one of points, lines or polygon, depending on the type_target in the geoobject_geometry table. So if the type_target is 0 or ``1``` it will create points, for 2 lines and 3 it will create polygons.

In following image is an explanation of which data are used for merging the tables.

In next step, the z_order will be computed through the given data. The z_order is use in mapnik to order the objects for the renderer, so that an object with a higher z_order will be overdrawn by an object with a lower z_order. To compute the z_order, every classification entry & every tag in tags will be gone a dict, where is defined how to rank an object. In the following image is an diagram how to calc the z_order.

In the same time, when compute the z_order, the system checks if the dict which contains the z_order values, has a value for is_road. If this is true, a new PlanetOsmRoads object will be created from the data in the previous generated osm object. In :numref:ohdm2mapnik_planet_osm_roads is a diagram how a PlanetOsmRoads object will be created.

The code of the converter is in ohdm2mapnik.py.

Usage

For production instance use:

$ docker-compose -f production.yml run --rm django python manage.py ohdm2mapnik

For local instance use:

$ docker-compose -f local.yml run --rm django python manage.py ohdm2mapnik

Optional parameters

--clear_mapnik_db Clear mapnik (osm2pgsql) data & tile cache

--cache [CACHE] Amount of object which will be handle at once.

--convert_points Points convert will be enabled, if set, only enabled geometries will be converted. By default, all geometries will be converted.

--convert_lines Lines convert will be enabled, if set, only enabled geometries will be converted. By default, all geometries will be converted.

--convert_polygons Polygons convert will be enabled, if set, only enabled geometries will be converted. By default, all geometries will be converted.

--sql_threads [SQL_THREADS] How many threads should be used, to insert entries into the database.

--not_fill_ohdm_tables Do not fill the ohdm cache table. Do this only if the ohdm cache tables already filled!

Hint: To reset just the mapnik tables planet_osm_* use docker-compose -f local.yml run --rm django python manage.py migrate ohdm zero. For faster database testing!