Topographical Data Quality

All layers under the Topo Group are sourced from LINZ (“NZTopo”), which is primarily sourced by LINZ from the 1:50:000 scale National Topographic Map Series. The positional accuracy of NZTopo data is given as a “statistical estimate of the degree to which the planimetric coordinates and elevations of digital spatial objects agree with the position of the corresponding object in the real world”.

The error in the position of the data results from errors inherent in the source maps resulting from the map production processes and/or the errors in the digitising processes used to convert the analog data to a digital format.

NZTopo data complies with the following statement of planimetric (x,y) accuracy:

“90% of well-defined points are within ±22m”.

NZTopo data complies with the following statement of vertical (z) accuracy:

“90% of well-defined points are within ±10m”.