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
19115:2003 - Metadata).
- 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
- 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
Metadata Guidelines are an indication of the scope and likely implementation
of the profile.
- 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.
- 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.
- 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:
Style: Terrace (archetype: Workers Cottage)
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.