3MAP - milestone 3.

metadata : extension elements

Metadata Extensions

The world can be seen from many perspectives. Any descriptive ontology will necessarily reflect the worldview and requirements of its author. A house (for example) can be seen from an architectural, social, economic, or environmental perspective, to name a few.

It is therefore useful for 3map to support multiple worldviews, by supporting multiple metadata element sets.

At the same time, it is useful to aggregate and standardise metadata wherever possible. Effective searching will be made possible by structured metadata. Variation in element sets should reflect the diversity of perspective, but also reflect commonality. Where worldviews converge, the same metadata elements should be used.

Therefore, where useful metadata standards exist they should be adopted. Where necessary, they should be extended. If formal extension is not appropriate, then extensions should still be logically consistent with existing and emerging standards wherever possible.

Extension element sets

The 3map core element set has been purposely kept to a minimum; it contains only descriptive elements that will necessarily be present at the creation of any feature. It is based on the set of Mandatory elements from OGC Metadata (ISO 19115:2003 - Metadata).

1. The logical primary extension set is Full OGC Metadata. This set of over 400 tags covers Identification, Browse Graphic, Keywords, Resolution, Usage, Constraints (including legal and security), Data Quality, Lineage, Temporal Extent, and so on. It specifies a hierarchy whereby the inclusion of an element can create mandatory requirements to include certain child elements, and the option to include others.
2. ANZLIC (the joint Australia/New Zealand government Spatial Information Council) is working on a community profile for OGC Metadata. When available, this would be a useful extension set for the region. In the meantime, the existing ANZLIC Metadata Guidelines are an indication of the scope and likely implementation of the profile.
3. Other OGC Extensions and Profiles (as defined in Annex C, clause C.6 of the OGC Metadata specification) are likely to emerge, and Ping will review those for suitability when they do, as well as participating the process of forming new profiles in response to the information publishing needs of our user community.
4. Ping will consider supporting arbitrary user-defined metadata element sets configured by advanced users, such that all users (including non-expert users) can take advantage of them.
5. The Virtual Terrain project is drafting the Vterrain culture classification to describe cultural features such as roads, power poles, and houses. This is currently a high-level set at the draft stage. Ping intends to join this effort, to help develop a more comprehensive cultural ontology. For example, it should be possible to specify attributes for a house such as:

   House:

   Style: Terrace (archetype: Workers Cottage)

   Single-storey

   Period: Victorian
   Built: 1890-1900

   Rear extension

   Period: Modern
   Built: 1950-1970

   Colour: Yellow

With this information the 3map system could build a procedural model on a defined block that would approximate the appearance of the feature (even interiors can be modeled procedurally - as in this paper from the European Commission's CHARISMATIC project). From a map view, the author could choose to represent it with an appropriate sigil; as the user approached it they could trigger a level-of-detail tree. All this could be set up in the client and server so as to allow the publication of this information by a non-expert user without 3D modelling or geospatial training. Optionally, the lowest level of the LOD tree could contain an accurate model of the building.