ckanext-geoview - Geospatial viewer for CKAN resources

This extension contains view plugins to display geospatial files and services in CKAN. It contains an OpenLayers based viewer originally developed by Philippe Duchesne and other view plugins that used to be part of ckanext-spatial.

Note: This is a work in progress, if you can help with OpenLayers or Leaflet development, check the Issues section for what needs to be done or add a new issue.

This extensions supports CKAN 2.7 onwards, including Python 3 support on CKAN 2.9 or higher.

Installation

To install ckanext-geoview on a production site:

1. Activate your CKAN virtual environment, for example:

   source /usr/lib/ckan/default/bin/activate
   

2. Install the ckanext-geoview Python package into your virtual environment:

   pip install ckanext-geoview
   

3. Add the relevant plugins to the ckan.plugins setting in your CKAN config file (by default the config file is located at /etc/ckan/default/production.ini). Check Available plugins to see which ones are available and if they require further configuration.

4. Add the resource_proxy plugin to the ckan.plugins setting.

5. Restart CKAN. For example if you've deployed CKAN with Apache on Ubuntu:

   sudo service apache2 reload
   

Development Installation

To install ckanext-geoview for development:

1. Clone the source:

   cd /usr/lib/ckan/default/src
   git clone https://github.com/ckan/ckanext-geoview.git
   

2. Activate your CKAN virtual environment, for example:

   source /usr/lib/ckan/default/bin/activate
   

3. Install the ckanext-geoview Python package into your python virtual environment:

   cd ckanext-geoview
   python setup.py develop
   

4. Continue with the main installation instructions above (step 3 onwards).

Available plugins

• OpenLayers Viewer
• Leaflet GeoJSON Viewer
• Leaflet WMTS Viewer
• Leaflet ESRI Shapefile Viewer

OpenLayers Viewer

The OpenLayers viewer provides access to different geospatial formats and services:

To enable it, add geo_view to your ckan.plugins setting.:

ckan.plugins = ... resource_proxy geo_view

If you want the geospatial views to be created by default, add the plugin to the following setting:

ckan.views.default_views = ... geo_view

The formats and services supported are:

(*) Resource formats are case insensitive

Support varies across formats, so you might want to deactivate the ones you are not interested in. To choose which formats to display, set the following configuration option:

ckanext.geoview.ol_viewer.formats = wms kml

To render Google Fusion Tables resources, a Google API Key must be provided in the ini file:

ckanext.geoview.gapi_key = <API Key here>

This key must be granted Fusion Tables permissions. More information on obtaining such a key can be found at https://developers.google.com/fusiontables/docs/v1/using#APIKey.

All configuration options relating to the OpenLayers viewer (ie those prefixed with ckanext.geoview.ol_viewer.*) are passed to the JavaScript module, where they are accessible on the options.ol_config object:

this.ckan.module('olpreview', function (jQuery, _) {

    // ...

    _onReady: function () {


        console.log(this.options.ol_config)

    }

    // ...

}

Other available configuration options are:

• ckanext.geoview.ol_viewer.hide_overlays: if set to True, overlays won't be visible by default (only the base layer)
• ckanext.geoview.ol_viewer.default_feature_hoveron: if set to True, feature data popup will be displayed when hovering on
• ckanext.geoview.ol_viewer.forward_ogc_request_params: if set to True, OGC request parameters that may be present in resource URLs will be kept as part of proxied service requests. If False (default), such parameters will be removed from URL when proxying requests.

Each instance of a view has the following configuration options that can override the global configuration :

• feature_hoveron: if set to True, feature data popup will be displayed when hovering on
• feature_style: JSON representation of an OpenLayers style, as accepted by the StyleMap constructor

Specific basemap support In addition to the basemap types described in Common base layers for Map Widgets, the OpenLayers viewer supports several other basemap types, namely TMS, WMTS, WMS

TMS example (here in Mercator projection)

ckanext.spatial.common_map.tms.url = <tms URL>
ckanext.spatial.common_map.tms.srs = EPSG:900913
ckanext.spatial.common_map.tms.layername = <TMS layer name>
ckanext.spatial.common_map.tms.resolutions = [156543.03390625,78271.516953125,39135.7584765625,19567.87923828125,9783.939619140625,4891.9698095703125,2445.9849047851562,1222.9924523925781,611.4962261962891,305.74811309814453,152.87405654907226,76.43702827453613,38.218514137268066,19.109257068634033,9.554628534317017,4.777314267158508,2.388657133579254,1.194328566789627,0.5971642833948135,0.29858214169740677,0.14929107084870338,0.07464553542435169,0.037322767712175846,0.018661383856087923,0.009330691928043961,0.004665345964021981,0.0023326729820109904,0.0011663364910054952,5.831682455027476E-4,2.915841227513738E-4,1.457920613756869E-4]
ckanext.spatial.common_map.tms.extent = [-20037508.34, -20037508.34,20037508.34, 20037508.34]

WMTS (in this case parameters will be fetched from online capabilities)

ckanext.spatial.common_map.type = wmts
ckanext.spatial.common_map.wmts.url = <wmts URL>
ckanext.spatial.common_map.wmts.layer = <WMTS layer name>
ckanext.spatial.common_map.wmts.srs = EPSG:4326

WMS

ckanext.spatial.common_map.wms.url = <wms URL>
ckanext.spatial.common_map.wms.layer = <layer name>
ckanext.spatial.common_map.wms.srs = EPSG:31370
ckanext.spatial.common_map.wms.extent = [141192.712000, 161464.403000, 158005.472000, 178169.335000]

Multi basemaps

Multiple basemaps can be defined in a separate file, and will result in a dropdown in the interface allowing to switch between basemaps. Basemap definition file is defined as follows

#ckanext.geoview.basemaps=%(here)s/basemaps.json

(here pointing to a file next to the ini file). This file is a JSON encoded array of basemap definitions reproducing the structure and syntax described above:

[
    {
        "title": "OSM",
        "type" : "custom",
        "url" : "http://tile.openstreetmap.org/{z}/{x}/{y}.png",
        "attribution" : " Map tiles & Data by OpenStreetMap, under CC BY SA."
    },
    {
        "title": "Blue Marble Mercator",
        "type" : "tms",
        "url" : "http://demo.opengeo.org/geoserver/gwc/service/tms/",
        "srs" : "EPSG:900913",
        "layername" : "nasa%3Abluemarble@EPSG%3A900913@png",
        "resolutions" : [156543.03390625,78271.516953125,39135.7584765625,19567.87923828125,9783.939619140625,4891.9698095703125,2445.9849047851562,1222.9924523925781,611.4962261962891,305.74811309814453,152.87405654907226,76.43702827453613,38.218514137268066,19.109257068634033,9.554628534317017,4.777314267158508,2.388657133579254,1.194328566789627,0.5971642833948135,0.29858214169740677,0.14929107084870338,0.07464553542435169,0.037322767712175846,0.018661383856087923,0.009330691928043961,0.004665345964021981,0.0023326729820109904,0.0011663364910054952,5.831682455027476E-4,2.915841227513738E-4,1.457920613756869E-4],
        "extent" : [-20037508.34, -20037508.34,20037508.34, 20037508.34]
    },
    {
        "title": "Blue Marble 4326",
        "type" : "tms",
        "url" : "http://demo.opengeo.org/geoserver/gwc/service/tms/",
        "srs" : "EPSG:4326",
        "layername" : "nasa%3Abluemarble@EPSG%3A4326@png",
        "resolutions" : [0.703125,0.3515625,0.17578125,0.087890625,0.0439453125,0.02197265625,0.010986328125,0.0054931640625,0.00274658203125,0.001373291015625,6.866455078125E-4,3.4332275390625E-4,1.71661376953125E-4,8.58306884765625E-5,4.291534423828125E-5,2.1457672119140625E-5,1.0728836059570312E-5,5.364418029785156E-6,2.682209014892578E-6,1.341104507446289E-6,6.705522537231445E-7,3.3527612686157227E-7],
        "extent" : [-180,-90,180,90]
    },
    {
        "title": "Opengeo WMS demo",
        "type" : "wms",
        "url" : "http://demo.opengeo.org/geoserver/ows",
        "layer" : "ne:NE1_HR_LC_SR_W_DR",
        "srs" : "EPSG:4326",
        "extent" : [-180,-90,180,90]
    }
]

When declared, this basemap list will override the ckanext.spatial.common_map properties.

URL specification

For WMS and WFS views, the URL must be specified carefully to get the desired result. In general, to browse the offered layers or features of a WMS or WFS endpoint, just specify the endpoint in the URL field of the resource, e.g.:

https://neo.sci.gsfc.nasa.gov/wms/wms

or

http://giswebservices.massgis.state.ma.us/geoserver/wfs

You can request individual layers/features using the "#" sign, e.g.:

https://neo.sci.gsfc.nasa.gov/wms/wms#MOD14A1_M_FIRE

or

http://giswebservices.massgis.state.ma.us/geoserver/wfs#GISDATA.MINLL1_ARC

N.B. For WFS this is the feature name without the qualifier, e.g. GISDATA.MINLL1_ARC and not massgis:GISDATA.MINLL1_ARC in the example above.

Leaflet GeoJSON Viewer

Note: This plugin used to be part of ckanext-spatial.

The Leaflet GeoJSON viewer will render GeoJSON files on a map and add a popup showing the features properties, for those resources that have a geojson format.

To enable it, add geojson_view to your ckan.plugins setting.:

ckan.plugins = ... resource_proxy geojson_view

If you want the views to be created by default on all GeoJSON files, add the plugin to the following setting:

ckan.views.default_views = ... geojson_view

You can use the ckanext.geoview.geojson.max_file_size configuration option to define the maximum file size (in bytes) that will be rendered in the map widget. Default is 25 Mb. Note that this relies on the resource size field being set (ie it will only work with uploaded files, not linked externally).

Leaflet WMTS Viewer

The Leaflet WMTS viewer will render WMTS (Web Map Tile Service) layers on a map for those resources that have a wmts format.

To enable it, add wmts_view to your ckan.plugins setting.:

ckan.plugins = ... resource_proxy wmts_view

If you want the views to be created by default on all WMTS resources, add the plugin to the following setting:

ckan.views.default_views = ... wmts_view

Leaflet ESRI Shapefile Viewer

The Leaflet Shapefile viewer will render ESRI Shapfiles (A ZIP archive contains the .shp, .shx, .dbf, and .prj files) on a map and add a popup showing the features properties, for those resources that have a shp format.

To enable it, add shp_view to your ckan.plugins setting.:

ckan.plugins = ... resource_proxy shp_view

If you want the views to be created by default on all Shapefiles, add the plugin to the following setting:

ckan.views.default_views = ... shp_view

The projection information (EPSG code, e.g., 4326 and 3857) will be loaded if there is a .prj file provided. You can also add a new field named 'resource_crs' in your custom resource fields or the following configuration option (The loading order is: .prj file, 'resource_crs' field, option and EPSG:4326/WGS84):

ckanext.geoview.shp_viewer.srid = 4326

The encoding of the shapefile can be defined by a custom resource field named 'encoding' in the metadata of the dataset or the following configuration option (The loading order is: 'encoding' field, option and UTF-8):

ckanext.geoview.shp_viewer.encoding = UTF-8

Common base layers for Map Widgets

The geospatial view plugins support the same base map configurations than the ckanext-spatial widgets.

Check the following page to learn how to choose a different base map layer:

http://docs.ckan.org/projects/ckanext-spatial/en/latest/map-widgets.html

Registering ckanext-geoview on PyPI

ckanext-geoview should be availabe on PyPI as https://pypi.python.org/pypi/ckanext-geoview. If that link doesn't work, then you can register the project on PyPI for the first time by following these steps:

1. Create a source distribution of the project:

   python setup.py sdist
   

2. Register the project:

   python setup.py register
   

3. Upload the source distribution to PyPI:

   python setup.py sdist upload
   

4. Tag the first release of the project on GitHub with the version number from the setup.py file. For example if the version number in setup.py is 0.0.1 then do:

   git tag 0.0.1
   git push --tags
   

Releasing a new version of ckanext-geoview

ckanext-geoview is availabe on PyPI as https://pypi.python.org/pypi/ckanext-geoview. To publish a new version to PyPI follow these steps:

1. Update the version number in the setup.py file. See PEP 440 for how to choose version numbers.

2. Create a source distribution of the new version:

   python setup.py sdist
   

3. Upload the source distribution to PyPI:

   python setup.py sdist upload
   

4. Tag the new release of the project on GitHub with the version number from the setup.py file. For example if the version number in setup.py is 0.0.2 then do:

   git tag 0.0.2
   git push --tags