Technology

Features

Madrona creates a system that can best be thought of as a feature spatial content management system. This starts with the Madrona PointFeature, LineFeature and PolygonFeature models. You can quickly extend these models to define your own spatial features specific to the purpose of your tool. Working with wind energy sites? Define a PolygonFeature and give it attributes for the type and number of turbines. Once you register your feature it’s mapped to a PostGIS table and automatically published through the REST API.

For more information consult the Madrona Feature documentation

@register
class WindEnergySite(PolygonFeature):
    ext = models.CharField(max_length="12")
    turbine_type = models.CharField(max_length="30")
    num_turbines = models.IntegerField()

    class Options:
        verbose_name = 'Wind Energy Site'
        form = 'myproject.forms.WindForm'
        links = (
            alternate('Shapefile',
                'mlpa.views.shapefile',
                select='single',
                type='application/shapefile'),

            alternate('KMZ (Google Earth)',
                'wind.views.kml_export',
                select='single multiple',
                type='application/vnd.google-earth.kmz',
                generic=True),

            related('Viewshed Map',
                'wind.views.viewshed_map',
                select='single',
                type='image/png'),

            edit('Delete',
                'wind.views.delete',
                select="single multiple",
                args=[WindArray],
                kwargs={'keyword_argument': True})
        )
				

REST API

The madrona REST API is the communication channel for the client and server and supports both GeoJSON and KML. Using it you can:

• Create, read, update and delete Features
• Copy and share Features between user groups
• Manage Features within a FeatureCollection
• Convert to export formats
• Access reports and related documents

Workspace Document

The workspace document is an important part of the REST API. It is a JSON document that the client fetches from the server at startup that describes the server-side API. Specifically::

• What Features are defined for the current user
• What Feature actions are available for the current user
• How Features relate to one another

• Creating, Updating, and Deleting Feature instances
• Editing actions that can be performed such as Copying and Sharing
• Managing relationships between Features
• Alternative export formats, such as KMZ or shapefile downloads
• Related files that can be downloaded, such as spreadsheet or pdf reports
• Reading feature attributes or reports

Because the API is well-defined through the workspace document, you can quickly and efficiently develop alternative client interfaces.

For more information consult the Madrona workspace specification

The JSON snippet below defines the wind energy site feature in the workspace document. You can see that URL's have been published for performing create and edit actions as well as accessing associated viewshed maps and KMZ/Shapefile exports.

{
    "title": "Wind Energy Site",
    "id": "features_windenergysite",
    "link-relations": {
        "self": {
          "uri-template": "/features/windenergysite/{id}/"
        },
        "create": {
          "uri-template": "/features/windenergysite/form/"
        },
        "alternate": [
          {
            "title": "Shapefile"
            "uri-template": "/features/windenergysite/links/shapefile/{id+}/",
            "select": "multiple",
            "rel": "related"
          }
        ],
        "related": [
          {
            "title": "KMZ (Google Earth)"
            "uri-template": "/features/windenergysite/links/kmz/{id+}/",
            "select": "multiple",
            "rel": "related"
          }
        ],
        "related": [
          {
            "title": "Viewshed Map"
            "uri-template": "/features/windenergysite/links/viewshed-map/{id+}/",
            "select": "single",
            "rel": "related"
          }
        ],
        "update": {
          "uri-template": "/features/windenergysite/{id}/form/"
        }
    }
}
			

3D Web Client

By default, madrona provides a robust HTML/Javascript client interface based on the 3D Google Earth plugin. It is not the only option for building a client interface but it does provide a complete solution out of the box.

The 3D web client allows features to be delivered using the expressive KML format. Using the workspace document the client will automatically configure a set of javascript widgets including the Google Earth Plugin, forming an end-to-end spatial content management system. Besides the Google Earth plugin itself, madrona provides a number of additional components.

KmlTree

kmltree is a javascript tree widget that can be used in conjunction with the Google Earth API. It replicates the functionality of the Google Earth desktop client, namely the ability to render complex KML documents very quickly and present the hierarchal contents of a KML document as an expandable, interactive tree view.

KmlEditor

KmlEditor provides the editing interface and menu to hook your features tree into the REST API. It will use the workspace document and configure the editing interface according to the API definition. The interface is context sensitive and provides the appropriate options for the selected features.

KML Drawing Tools

Madrona provides a robust set of drawing and editing tools for the Google Earth Plugin. These play a part in the larger workflow of creating, editing and sharing features.

2D Web Client

Madrona provides core support for 2D web mapping through its REST API allowing a variety of possibilities for developing 2D client interfaces. Additional client-side widgets are currently in development for Madrona. You can contribute to that effort or take a look at frameworks such as GeoExt. OpenLayers is currently seen as the most robust 2D mapping client with support for vector editing, UTF-Grid encoding and other advanced features most often needed by Madrona-based tools.

GeoJSON Output

The Madrona REST API provides support for GeoJSON output of any Feature by default. This was challenging because the GeoJSON specification does not currently support a hierarchical structure (a collection within a collection) and Madrona does through its FeatureCollection class. To get around this Madrona supports two strategies, a ‘flat’ strategy that strictly follows the spec and a ‘nest_feature_set’ strategy which extends the GeoJSON specification to tell you all of the child collections that are within a given collection. In this way you can quickly query down into an arbitrary hierarchy of features.

collection1
  |- polygon1
  |- collection2
    | - polygon2
    | - polygon3
			

Learn more about GeoJSON output

Madrona can integrate with a variety software products, libraries, and services both server and client-side. We do this all the time on a project-by-project basis. Much of this is possible through the power of open data standards, API's and the web.

Tools we're leveraging:

• Mapbox/Tilemill - UTFGrid map production/publishing
• Twitter Bootstrap - simplified UI scaffolding and interaction
• Knockout - dynamic Javascript UI's
• Amazon S3 - cloud-based storage
• Grass - raster analysis
• Arc2Earth - Map tile production in ArcMap

Tools we want to leverage soon:

• ArcServer
• CartoDB