keithamoss / unearthed

Resources for developers in the Unearthed Hackathon

Unearthed

Resources for developers using Landgate's SLIP data platform in the Unearthed Hackathon.

This new release of the SLIP platform is currently in beta and is the product of a partnership between Landgate and Google built on the Google Maps Engine cloud-based platform.

Resources Map Service

Landgate have prepared a map service containing more than 50 resource and environment related datasets from a range of WA Government agencies.

The data are available to inspect and query in the SLIP Resources map viewer.

layers.json

This JSON dump contains the list of layers in the map service, along with their layerIds, layerKeys, datasourceIds, URIs for their datasources, and some additional useful metadata.

{
  layerId: /* A globally unique ID used to refer to this layer */
  layerKey: /* The layer key - For the GMaps JS Lib. Not unique. */
  name: /* The layer name */
  description: /* The layer description */
  bbox: /* An array of four numbers (west, south, east, north) which define 
    the rectangular bounding box covered by the layer as latitude and longitude in decimal degrees */
  datasourceType: /* The type of layer - one of "table" or "image" */
  datasources: /* The path to the GME API resource of the more specific version of this asset. 
    Used for querying features and only applies to datasourceType "image". */
}

For easier viewing of layers.json use the JSONView Chrome extension or the free online JSON Visualisation tool.

Coming Soon: We're hard at work on a brand new search and discovery tool! We'll intergrate all of this information and more in a single easy to use web interface with handy tools for developers.

Locate Map Service

We also have our Locate map service available with a wide variety of WA Government data available for use. For more information check out its GitHub page.

Accessing Data

This section will serve as a brief introduction to developing off of the SLIP platform. More detailed information, step-by-step guides, tutorials, code samples, and much more are available on our SLIP Developer Documentation.

Code samples are available for all of these libraries over on our SLIP Code Samples page. Check them out!

Spatial whatnow?

If you're new to working with spatial data we can highly recommend a read through of GIS for Dummies.

I just need to be able to see something on a map

If you simply need to be able to generate a visual representation of the data (e.g. display it on a map, generate a once-off image) you have three APIs available:

• WMS (Web Mapping Service)
• WMTS (Web Map Tile Service)
• Google Maps JavaScript API

To consume these APIs you'll want a client library to do the heavy lifting for you. Fortunately you're spoilt for choice!

WMS & WMTS

OpenLayers, OpenLayers 3 (still in beta), Leaflet, amd MapBox JS can all be used to easily consume WMS and WMTS APIs.

WMS and WMTS access require the mapId.

Locate's mapId: 09372590152434720789-00913315481290556980

Resources mapId:** 09372590152434720789-11493353092997567468

Google Maps JavaScript API

The Google Maps JavaScript API has connectors specifically for Google Maps Engine.

There are two ways of accessing data in Google Maps Engine:

1. Via the layerId (recommended - see layers.json), or
2. By supplying a mapId and a layerKey.

Locate's mapID: 09372590152434720789-00913315481290556980

Resources mapId:** 09372590152434720789-11493353092997567468

Desktop

For viewing and manipulating spatial data on the desktop you can't go past QGIS, the open source Geographic Information System.

Other

For non-client facing calls you can either build the URL yourself or use tools like OWSLib (Python) or GeoTools (Java).

I need to be able to retrieve and run queries against the raw data

If your focus is actually getting at the raw data itself, running queries against it, and analysing it then the Google Maps Engine API is your friend.

The GME API is a RESTful API that speaks and consumes JSON. Our Getting Started documentation and GME API Tutorial have more information on working with the GME API. We've also got a few code samples demonstrating more advanced uses of the GME API.

Accessing data via the Google Maps Engine API or WFS is at the datasource-level and requires a datasource assetId to be provided (see layers.json).

GME API: https://www.googleapis.com/mapsengine/v1/tables/{assetId}/features?version=published&key={your-api-key}

WFS: https://clients6.google.com/mapsengine/wfs_experimental/wfs/{assetId}/?REQUEST=GetCapabilities&SERVICE=WFS2.0&assetVersion=published

Visualising GeoJSON

You can also map the GeoJSON data that the GME API returns. OpenLayers and Leaflet support GeoJSON natively and GitHub itself will render GeoJSON files.

Note: WFS access is available if needs be, but it's still an experimental service. See our WFS page for more information.

Command-line

If command-line is more your thing there's work underway to support the GME API within the GDAL. See the GMEDriver documentation for more information.

Error: "This resource is too large to be accessed via this API call."

If you receive this error message let us know and we can provide the details for an account with special access to larger data sources.

Tools

APIs

For playing with APIs we recommend use of the Postman HTTP Client. It makes exploring and testing APIs a breeze.

Desktop Apps

If you need to manipulate, convert, and analyse spatial data QGIS is the best open source Geographic Information System.

Make your own maps

If you have data you need to map you're spoilt for choice these days:

• Google Maps Engine (a free version of the same platform SLIP is built on (subject to these limits).
• CartoDB
• TileMill
• MangoMap