The contexts that are likely to trigger deviations or extensions with respect to this description are likely to be driven by:
differences in perspective – to what extent does elevation data fit the model for a priority fundamental dataset;
differences in funding models – to what extent is the primary funding coming from central government vs local government vs research vs business;
differences in technology – to what extent has the technological context moved on from that envisioned by those who wrote the strategy;
societal expectations – to what extent has societies expectations of spatial data moved on from the timeframe of the strategy.
The very fact that I am raising these possible issues so soon after the strategy was written is an indication of the rate of societal and technological change that we need to acknowledge in establishing a framework that is going to withstand future shocks.
Elevation data as a priority fundamental data set:
One of the key issues raised by the workshop was the diversity of expectation and definition that can be used for elevation. There is no doubt that elevation in its broadest sense is a priority fundamental issue for Government, what isn’t clear is that a dataset can or even should be identified to match these expectations. Elevation implies a vertical measure of a set of locations above a reference surface. But as the Australian workshop identified, the selection and definition of both the set of locations and the reference surface is open to wide discussion and there is no single correct answer, rather a family of possible sets of locations and of possible reference surfaces. Further the locations are dynamic – due to building changes, coastal and hill erosion, vegetation and land use changes. The references surfaces are both dynamic (tectonic movement and sea level change) and poorly defined (sea surface specifications). Finally what is being defined has no intrinsic infrastructural value, so there is no basis on which to define any particular location or reference surface as of paramount importance to Government as a whole. Even setting aside the choice of elevation specification, the data formats that are usually used for elevation are themselves suspect, being based on a two (strictly 2.5) dimensional view of a three or even four (if time is included) dimensional space. This view is adequate for many purposes and has served the geospatial community well for the last few decades, but with the increasing use of dynamic three dimensional viewers (eg Google Earth) it is worth questioning whether the historic approach remains the best equipped to cope with modern demands (eg full spectrum LiDAR) and therefore whether a NZ EDF should be more forward than backward looking.
Existing investment patterns
Historically elevation was only available as contours and survey spot heights, which were all sourced from within Government supported by registered surveyors in the business community and aerial photography suppliers, but over the last decade many Regional and City Councils have made significant investment in elevation data by purchasing LiDAR from business suppliers, even commodity GPS units can provide elevation as an integral part of location, and boats routinely have depth sounding and logging capability. So the variety of potential sources of elevation data in the broadest sense is greatly increased and the Government is a relative newcomer in using these newer technologies as a source of primary elevation data. Elevation data is also available from stereo satellite imagery. Consequently it is currently the local government and business sectors that have the greatest equity in elevation data not central government. The principles of the geospatial strategy should still apply for public access, since the citizens within each region that have paid, but the right of central government to bulk access is a matter for debate and a funding mechanism needs to be established to achieve a partnership between Central Government and Local Government for elevation data investment and ownership.
Technological changes.
When the strategy was written even widespread access to broadband (<10mb/s)> on-demand processed data as an integral part of a that infrastructure. This shifts the goal post from having to think of elevation in terms of a single formally defined / managed dataset describing the elevation surface of one set of locations (eg bare earth) against one reference surface (eg WGS84 ellipsoid), albeit at multiple nested resolutions, to a system that matches an evolving set of raw data sources with their computational codes (processing workflows) to create data in a variety of formats, with a choice of reference surface, and where possible conversion between different location specifications (surface vs bare-earth etc). This is the on-demand managed workflow approach being pioneered by the SCENZ-Grid project, supported by a significant resource of GRID based computational capability.
Societal expectations.
New Zealanders are quick to pick up new technologies such as Google Maps (2D) and Google Earth (2.5D) with their ability to integrate with on-line photo albums, videos, blogs, geoRSS feeds, uploaded GPS tracks etc. There is a general expectation that 'of course' local and central government agencies and researchers have access to far better data than they see and use at home for free. Do they? Should they? What needs to happen to ensure that we all have access to the best information around and where widespread use generates demand for continuous improvement?
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