Issues to resolve


Bare surface classes

posted Nov 28, 2011, 5:54 PM by David Pairman   [ updated Nov 30, 2011, 7:13 PM ]

Some bare surfaces do not fit into the current group of bare surface classes - how do we fix this?  


The ‘bare surfaces’ group of classes doesn’t fill the thematic space available – for example there is no bare rock category available below the alpine environment unless it’s a landslide or along a lake or river. We’re considering the merit if merging ‘Alpine Gravel and Rock’ with ‘River and Lakeshore Gravel and Rock’ into a new generic ‘Gravel and Rock’ class. What do you think?

Collaborating agencies: Please leave your views as comments below, along with your name/organisation.

Remove redundant boundaries?

posted Nov 28, 2011, 5:46 PM by David Pairman   [ updated Nov 30, 2011, 7:14 PM ]

Should boundaries between identical classes be removed?  


Our compilation to date has maintained an absolute respect for earlier mapping by not removing any existing boundaries, but inserting new boundaries along new or corrected land cover edges. As we do this, segments of former polygons have their attributes corrected so they often become described identically to their former neighbours. The old boundaries between neighbouring polygons therefore ceases to delineate any real difference between one side and the other so we’re contemplating a pre-release dissolve of these now-spurious boundaries to ‘clean up’ the database. What do you think?

Collaborating agencies: Please leave your views as comments below, along with your name/organisation.

Topo50 coastline

posted Nov 28, 2011, 5:39 PM by David Pairman   [ updated Nov 30, 2011, 7:15 PM ]

Should we replace the LCDB current coastline with the TOPO50 coastline? 


The coastline of LCDB seems unique to LCDB. It differs from Topo50 which most would consider to be New Zealand’s authoritative coastline and (before our smoothing) it contained segments of stepped linework from early raster classification. We are contemplating delimiting the LCDB with a Topo50 coastline (through an as-yet undetermined process). What do you think?

Collaborating agencies: Please leave your views as comments below, along with your name/organisation.

Undersized polygons - remove?

posted Nov 28, 2011, 5:20 PM by David Pairman   [ updated Nov 30, 2011, 7:16 PM ]

There are many polygons smaller than the LCDB  minimum map unit size of 1 hectare. Should we remove these, and if so, at what threshold?  


The LCDB claims a minimum map unit size of 1 ha. We’ve removed some of the really small polygons (< 0.05 ha) but among the 400,000 polygons in the database there still remain 67,000 polygons (17%) smaller than a hectare, 16,000 polygons (4%) smaller than half a hectare and 1,200 smaller than 0.2 hectares. From our observation, the smaller they are the less likely these polygons are to resolve any real difference in land cover so we’re contemplating a further elimination step before release in July. What do you think?

Collaborating agencies: Please leave your views as comments below, along with your name/organisation.

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