bcdata 0.3.3

Python tools for quick access to DataBC geo-data available via WFS

bcdata

Python and command line tools for quick access to DataBC geo-data available via WFS/WCS.

There is a wealth of British Columbia geographic information available as open data, but direct file download urls are not available and the syntax to accesss WFS via ogr2ogr and/or curl/wget can be awkward.

This Python module and CLI attempts to simplify downloads of BC geographic data and smoothly integrate with existing Python GIS tools like fiona and rasterio.

Note

• it is the user's responsibility to check the licensing for any downloads, data are generally licensed as OGL-BC
• this is not specifically endorsed by the Province of Britsh Columbia or DataBC
• use with care, please don't overload the service

Installation

$ pip install bcdata

To enable autocomplete of dataset names (full object names only) with the command line tools, add this line to your .bashrc as per this guide.

eval "$(_BCDATA_COMPLETE=source bcdata)"

Usage

Typical usage will involve a manual search of the DataBC Catalogue to find a layer of interest. Once a dataset of interest is found, note the key with which to retreive it. This can be either the id/package name (the last portion of the url) or the Object Name (Under Object Description).

For example, for BC Airports, either of these keys will work:

• id/package name: bc-airports
• object name: WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW

Python module

>>> import bcdata
>>> geojson = bcdata.get_data('bc-airports', query="AIRPORT_NAME='Terrace (Northwest Regional) Airport'")
>>> geojson
{'type': 'FeatureCollection', 'features': [{'type': 'Feature', 'id': 'WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW.fid-f0cdbe4_16811fe142b_-6f34', 'geometry': {'type': 'Point', ...

CLI

There are several commands available:

$ bcdata --help
Usage: bcdata [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  bc2pg  Download a DataBC WFS layer to postgres - an ogr2ogr wrapper.
  cat    Write DataBC features to stdout as GeoJSON feature objects.
  dem    Dump BC DEM to TIFF
  dump   Write DataBC features to stdout as GeoJSON feature collection.
  info   Print basic metadata about a DataBC WFS layer as JSON.
  list   List DataBC layers available via WFS

list

$ bcdata list --help
Usage: bcdata list [OPTIONS]

  List DataBC layers available via WFS

Options:
  -r, --refresh  Refresh the cached list
  --help         Show this message and exit.

info

$ bcdata info --help
Usage: bcdata info [OPTIONS] DATASET

  Print basic metadata about a DataBC WFS layer as JSON.

  Optionally print a single metadata item as a string.

Options:
  --indent INTEGER  Indentation level for JSON output
  --count           Print the count of features.
  --name            Print the datasource's name.
  --help            Show this message and exit.

dump

$ bcdata dump --help
Usage: bcdata dump [OPTIONS] DATASET

  Dump a data layer from DataBC WFS to GeoJSON

    $ bcdata dump bc-airports
    $ bcdata dump bc-airports --query "AIRPORT_NAME='Victoria Harbour (Shoal Point) Heliport'"
    $ bcdata dump bc-airports --bounds xmin ymin xmax ymax

  The values of --bounds must be in BC Albers.

   It can also be combined to read bounds of a feature dataset using Fiona:
     $ bcdata dump bc-airports --bounds $(fio info aoi.shp --bounds)

Options:
  --query TEXT         A valid CQL or ECQL query, quote enclosed (https://docs
                       .geoserver.org/stable/en/user/tutorials/cql/cql_tutoria
                       l.html)
  -o, --out_file TEXT  Output file
  --bounds TEXT        Bounds: "left bottom right top" or "[left, bottom,
                       right, top]".
  --help               Show this message and exit.

cat

$ bcdata cat --help
Usage: bcdata cat [OPTIONS] DATASET

  Download a DataBC WFS layer and write to stdout as GeoJSON feature
  objects. In this case, cat does not concatenate.

Options:
  --query TEXT               A valid `CQL` or `ECQL` query (https://docs.geose
                             rver.org/stable/en/user/tutorials/cql/cql_tutoria
                             l.html)
  --indent INTEGER           Indentation level for JSON output
  --bounds TEXT              Bounds: "left bottom right top" or "[left,
                             bottom, right, top]".
  --compact / --not-compact  Use compact separators (',', ':').
  --dst-crs, --dst_crs TEXT  Destination CRS.
  -p, --pagesize INTEGER     Max number of records to request
  -s, --sortby TEXT          Name of sort field
  --help                     Show this message and exit.

dem

$ bcdata dem --help
Usage: bcdata dem [OPTIONS]

  Dump BC DEM to TIFF

Options:
  -o, --out_file TEXT        Output file
  --bounds TEXT              Bounds: "left bottom right top" or "[left,
                             bottom, right, top]".  [required]
  --dst-crs, --dst_crs TEXT  Destination CRS.
  -r, --resolution INTEGER
  --help                     Show this message and exit.

bc2pg

$ bc2pg --help
Usage: bcdata bc2pg [OPTIONS] DATASET

  Download a DataBC WFS layer to postgres - an ogr2ogr wrapper.

     $ bcdata bc2pg bc-airports --db_url postgresql://postgres:postgres@localhost:5432/postgis

  The default target database can be specified by setting the $DATABASE_URL
  environment variable.
  https://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls

Options:
  -db, --db_url TEXT         SQLAlchemy database url
  --table TEXT               Destination table name
  --schema TEXT              Destination schema name
  --query TEXT               A valid `CQL` or `ECQL` query (https://docs.geose
                             rver.org/stable/en/user/tutorials/cql/cql_tutoria
                             l.html)
  -p, --pagesize INTEGER     Max number of records to request
  -s, --sortby TEXT          Name of sort field
  -w, --max_workers INTEGER  Max number of concurrent requests
  --dim TEXT                 Force the coordinate dimension to val (valid
                             values are XY, XYZ)
  --fid TEXT                 Primary key of dataset
  --help                     Show this message and exit.

CLI examples

Search the data listing for airports:

  $ bcdata list | grep AIRPORTS
  WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW

Describe a dataset. Note that if we know the id of a dataset, we can use that rather than the object name:

$ bcdata info bc-airports --indent 2
{
  "name": "WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW",
  "count": 455,
  "schema": {
    "properties": {
      "CUSTODIAN_ORG_DESCRIPTION": "string",
      "BUSINESS_CATEGORY_CLASS": "string",
      "BUSINESS_CATEGORY_DESCRIPTION": "string",
      "OCCUPANT_TYPE_DESCRIPTION": "string",
      ...etc...
    },
    "geometry": "GeometryCollection",
    "geometry_column": "SHAPE"
  }
}

The JSON output can be manipulated with jq. For example, to show only the fields available in the dataset:

$ bcdata info bc-airports | jq '.schema.properties'
{
  "CUSTODIAN_ORG_DESCRIPTION": "string",
  "BUSINESS_CATEGORY_CLASS": "string",
  "BUSINESS_CATEGORY_DESCRIPTION": "string",
  "OCCUPANT_TYPE_DESCRIPTION": "string",
  etc...
}

Dump data to geojson (EPSG:4326 only):

$ bcdata dump bc-airports > bc-airports.geojson

Get a single feature and send it to geojsonio (requires geojson-cli). Note the double quotes required around a CQL FILTER provided to the --query option.

$ bcdata dump \
  WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW \
  --query "AIRPORT_NAME='Terrace (Northwest Regional) Airport'" \
   | geojsonio

Save a layer to a geopackage in BC Albers:

$ bcdata cat bc-airports --dst-crs EPSG:3005 \
  | fio collect \
  | fio load -f GPKG --dst-crs EPSG:3005 airports.gpkg

Load a layer to postgres:

$ bcdata bc2pg \
  bc-airports \
  --db_url postgresql://postgres:postgres@localhost:5432/postgis

Projections / CRS

CLI

bcdata dump returns GeoJSON in WGS84 (EPSG:4326).

bcdata cat provides the --dst-crs option, use any CRS the WFS server supports.

bcdata bc2pg loads data to PostgreSQL in BC Albers (EPSG:3005).

Python module

bcdata.get_data() defaults to EPSG:4236 but any CRS can be specified (that the server will accept).

Development and testing

$ mkdir bcdata_env
$ virtualenv bcdata_env
$ source bcdata_env/bin/activate
(bcdata_env)$ git clone [e-mail]:smnorris/bcdata.git
(bcdata_env)$ cd bcdata
(bcdata_env)$ pip install -e .[test]
(bcdata_env)$ py.test

Other implementations

• bcdata R package

• OWSLib has basic WFS capabilities

• GDAL / curl / wget:

    # list all layers
    # querying the endpoint this way doesn't seem to work with `VERSION=2.0.0`
    ogrinfo WFS:http://openmaps.gov.bc.ca/geo/ows?VERSION=1.1.0
  
    # define a request url for airports
    airports_url="https://openmaps.gov.bc.ca/geo/pub/WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW/wfs?service=WFS&version=2.0.0&request=GetFeature&typeName=WHSE_IMAGERY_AND_BASE_MAPS.GSR_AIRPORTS_SVW&outputFormat=json&SRSNAME=epsg%3A3005"
  
    # describe airports
    ogrinfo -so $airports_url OGRGeoJSON
  
    # dump airports to geojson
    ogr2ogr \
      -f GeoJSON \
      airports.geojson \
      $airports_url
  
    # load airports to postgres
    ogr2ogr \
      -f PostgreSQL \
      PG:"host=localhost user=postgres dbname=postgis password=postgres" \
      -lco SCHEMA=whse_imagery_and_base_maps \
      -lco GEOMETRY_NAME=geom \
      -nln gsr_airports_svw \
      $airports_url
  
    # Try requesting a larger dataset - ungulate winter range
    uwr_url="https://openmaps.gov.bc.ca/geo/pub/WHSE_WILDLIFE_MANAGEMENT.WCP_UNGULATE_WINTER_RANGE_SP/wfs?service=WFS&version=2.0.0&request=GetFeature&typeName=WHSE_WILDLIFE_MANAGEMENT.WCP_UNGULATE_WINTER_RANGE_SP&outputFormat=json&SRSNAME=epsg%3A3005"
  
    # The request only returns the first 10,000 records
    ogr2ogr \
      uwr.shp \
      -dsco OGR_WFS_PAGING_ALLOWED=ON \
      $uwr_url
  
    # wget works too, but still only 10k records
    wget -O uwr.geojson $uwr_url