Page Comparison

The Local Hub contributing hub must provide three services:

• publication of ISO19115-3 metadata through a catalogue service - nominally GeoNetwork

• publication of Web Mapping Service and Web Coverage Service according to AusSeabed protocols

• direct download of Local Contributing Hub products through HTTP protocol

The Local Hub contributing hub must also provide a description of their holdings in an Excel format that can be read by the Exploring For The Future Portal.

Publication of ISO19115-3 metadata

Most large organisations that distribute spatial data catalogue the existence of that data using a metadata catalogue system such as GeoNetwork. AusSeabed Local Hubs contributing hubs must provide a catalogue that can be harvested by AODN (and others) using GeoNetwork. AusSeabed requires that metadata entries be systematised to support downstream search and filter.

General Background

There are several metadata standards for describing spatial data, but ISO19115 continues to grow in popularity. The standard itself provides a wide range of flexibility in the forms of XML that it accepts. It is rarely possible for a system to understand the semantics of every component of XML that meets the standard. Likewise, the standard permits different ways of representing the same information. What has emerged are profiles of the ISO19115 that have agreed meaning among subsets of the spatial community. These can also include variations such as additional mandatory fields. In AusSeabed’s case the most notable is the marine community profile (ISO19115-3) that is designed for marine purposes (most notably documenting marine specimen samples). Worthy of similar mention is GA’s Community Profile that forces some metadata tags to be mandatory.

Technical Details

Geonetwork provides at least three method of editing metadata: a) a simple interface; b) the full interface; and c) an XML editor. Most metadata can be entered in the simple interface; however, a number of fields require the full editing interface or XML editor (or import) including:

<mri:descriptiveKeywords>
  <mri:MD_Keywords>
    <mri:keyword>
      <gco:CharacterString>marine</gco:CharacterString>
    </mri:keyword>
    <mri:type>
      <mri:MD_KeywordTypeCode codeList="codeListLocation#MD_KeywordTypeCode" codeListValue="theme"/>
    </mri:type>
  </mri:MD_Keywords>
</mri:descriptiveKeywords>

...

<mcc:code>
<gcx:Anchor xlink:href="http://vocab.nerc.ac.uk/collection/C17/current/09SS">Southern Surveyor</gcx:Anchor>
</mcc:code>

Likewise, start and end ports should link to a valid vocabulary entry. E.g. SeaDataNet Ports:

http://vocab.nerc.ac.uk/collection/C38/current/BSH244/

AusSeabed protocols for publishing Web Mapping Service and Web Coverage Services

For consistency, L3 products need to be presented through web services in the same way. Each L3 product served through a Web Mapping Service (WMS) must be presented as a group layer:

Naming of layers

The layers should follow a consistent form. The form chosen for GA’s holdings is: 

{Location}_{Product Type}_{Publication Date}_{Resolution}_{Product Code}

...

Bathymetry

All GeoTIFF images must be provided in Cloud Optimised form. For large images we have image overlays at 2 4 8 16 32 scales.

Hillshade

The hillshade must be produced with azimuth 30 degrees, altitude 45 degrees and z scaling factor of 2. For geographic projection images, a scaling factor of 111120 must be applied.

Extent Polygon

The extent polygon must contain metadata attributes of the layer (in any order):

For surveys, the follow attributes are to be used:

Direct download of

...

Contributing Hub products

All L3 products must be downloadable using standard HTTP protocols (http/https). They should have a consistent file format. Individual AusSeabed Data Hubs may have limitations on their capacity to define file names (i.e. because of integration with other systems). However, where they do have capacity to define names, the following convention may be useful:

...

Description of holdings for inclusion in EFTF Portal

Display names on the portal

{Location} {Product Type} {Publication Date} {Resolution} ({Organisation if not GA}) [{Identifier}]

...