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Extract OSM data with Osmium

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  • avatar
    Name
    YuChun Tsao
    Twitter

The previous article (import-osm-data-into-postgis-with-osm2pgsql) introduces how to import OSM data into PostGIS through osm2pgsql. In this article, I will extract OSM with Osmium and import customized osm.pbf into PostGIS.

Environment

  • Ubuntu 18.04
  • CMake 3.24.1

Installation

Follow the official documentation to install: Osmium Command Line Tool

Download OSM data

Download from geofabrik

In this article, I will use taiwan-latest.osm.pbf for the next step.

You can use osmium fileinfo to inspect your osm.pbf file

osmium fileinfo taiwan-latest.osm.pbf

File:
  Name: taiwan-latest.osm.pbf
  Format: PBF
  Compression: none
  Size: 114332934
Header:
  Bounding boxes:
    (118.1036,20.72799,122.9312,26.60305)
  With history: no
  Options:
    generator=osmium/1.14.0
    osmosis_replication_base_url=http://download.geofabrik.de/asia/taiwan-updates
    osmosis_replication_sequence_number=3577
    osmosis_replication_timestamp=2023-01-14T21:21:25Z
    pbf_dense_nodes=true
    pbf_optional_feature_0=Sort.Type_then_ID
    sorting=Type_then_ID
    timestamp=2023-01-14T21:21:25Z

You can use -e option to show more information about the pbf.

Creating geographic extracts

Extract with bounding box

osmium extract \
  -s simple \
  -b 121.561,25.030,121.568,25.036 \
  taiwan-latest.osm.pbf \
  -o bounding_box_output.pbf

-s, --strategy
Osmium offers three different extract strategies simple, complete_ways(default) and smart. Their results are different, more or less OSM objects will be included in the output.
More information about extract strategy can read manual of Osmium.

Extract with bounding box

Extract with OSM boundary

You can find relation id from OpenStreetMap.

In my case, I typed taipei keyword in search bar to find the relation id of Taipei City as 1293250.

Get relation id from openstreetmap

Extract the boundary through the relation id of Taipei City.

osmium getid -r -t taiwan-latest.osm.pbf r1293250 -o taipei-boundary.osm

Then extract the pbf file of Taipei City through taipei-boundary.osm.

osmium extract -s simple -p taipei-boundary.osm taiwan-latest.osm.pbf -o boundary_output.pbf
Extract with OSM boundary

Extract with GeoJSON

If you have geographic data in GeoJSON format also used to extract the data.

I got a circle from geojson.io as my input geojson data.

Example GeoJSON

Extract data through the circle in GeoJSON format.

osmium extract -s simple -p polygon.geojson taiwan-latest.osm.pbf -o geojson_output.pbf
Extract with GeoJSON

Several extracts with config file

The config file is in JSON format. The top-level is an object which contains at least an extracts array. It can also contain a directory entry which names the directory where all the output files will be created.

config.json

{
  "extracts": [
    {
      "output": "bounding_box_output.pbf",
      "output_format": "pbf",
      "description": "extract with bbox",
      "bbox": [121.561, 25.03, 121.568, 25.036]
    },
    {
      "output": "boundary_output.pbf",
      "description": "extract with osm boundary",
      "polygon": {
        "file_name": "taipei-boundary.osm",
        "file_type": "osm"
      }
    },
    {
      "output": "geojson_output.pbf",
      "description": "extract with geojson polygon",
      "polygon": {
        "file_name": "polygon.geojson",
        "file_type": "geojson"
      }
    }
  ],
  "directory": "./output/"
}

The output directory must exist.

Extract data with this config file.

osmium extract -s simple -c config.json taiwan-latest.osm.pbf

After execution you will be able to find the pbf in the output directory.

$ tree output
output
├── boundary_output.pbf
├── bounding_box_output.pbf
└── geojson_output.pbf

0 directories, 3 files

References