David Pairman, James Shepherd and Peter Newsome
03 Sep 2012 to 03 Sep 2012
Version 3.0 of the Land Cover Database (LCDB v3.0), released in June, represents a significant step forward in the digital mapping of New Zealand’s land cover. While new satellite imagery has been used to provide the additional 2008/09 time step, a variety of other techniques have been used to improve the line work, and make the data more consistent with other datasets. These include removing pixel artefacts from previous satellite classifications, standardising on the Topo50 coastline, and making rubber-sheet adjustments on existing vector work where necessary. The paper will cover these processing steps in LCDB v3.0 generation along with the techniques developed to quickly identify both real temporal change and mapping errors in the earlier time steps (1996/07 and 2001/02). Over 100,000 polygons or part-polygons were changed in version 3, so efficient semi-automated workflows are critical. With LCDB v4 due in mid-2014, we are looking at better methods to integrate other existing datasets, to report errors found, and to identify and map change. Ideas and progress towards these goals will be covered in this paper. In particular we are developing methods to automate the segmentation of satellite imagery reducing the manual effort to digitise line work from the imagery.