Digital Cadastral Database Related Datasets

Digital Cadastral Database (DCDB) mapping dataset

This dataset consists of the Static Feature table, which mapped the DCDB SUFI at the time of conversion to Landonline to its resultant Landonline SUE. A table called crs_static_feat_id was populated as each DCDB database was converted and loaded to Landonline, and thereafter remains as static data, ie it is not maintained. The DCDB for each Land District has been decommissioned and this dataset would only be relevant to those users wishing to migrate from a system based on the prior DCDB data to Landonline.

A file called sfi.crs was produced. It contains an extract from the crs_static_feat_id table after the last DCDB database was converted and loaded to Landonline. The Digital Cadastral Database (DCDB) mapping dataset can be added to a BDE supply as a one-off exercise.

The following related documentation can be viewed or downloaded:

You can also check background documentation about the Digital Cadastral Database.

Landonline Final DCDB Coordinates

LINZ was asked how end-users of the cadastral parcel fabric could maintain the relative position of other spatial data, such as utility objects, following the significant shifts in coordinates resulting from the Survey Conversion project.

Many of these users had mapped their features in relation to the adjacent parcel boundaries. Survey conversion typically moved these boundaries by significant amounts to new survey-accurate positions. However this left these other features "out of terms". To assist these users in transforming those features to maintain the relativity, LINZ made available the final DCDB coordinates as they were loaded into Landonline between 2000 and 2002. This data can be used to determine how far individual points have moved by comparing the converted DCDB coordinate with the current coordinates (as obtained from a Bulk Data Extract). These "shifts" can then be used to calculate shifts for other data that was referenced to the DCDB. It should be noted that data not referenced to the DCDB, such as points surveyed by GPS or in terms of the survey control framework should NOT be transformed, as they should already be in the correct position.

A file called coo_orig.crs was produced. It contains an extract from the crs_coordinate table of the DCDB converted coordinates. Some coordinates are now decommissioned (status = DECM). The fields extracted are the same as the coo2.crs file.

The final DCDB coordinates can be added to a BDE supply as a one-off exercise.

Additional information is available for:

  • survey conversion
  • future stability of the parcel fabric (below), and
  • determining the accuracy of coordinates (below).

Future stability of the parcel fabric

Any new surveys and subdivisions will also need to be integrated into the parcel fabric and will affect the coordinates. In the Survey Conversion Areas the shifts are likely to be small (generally at the centimetre level). These areas can be seen via the Survey Conversion page. However in other areas, particularly non-urban areas, new surveys may result in significant shifts to the parcel fabric, reflecting the comparatively low accuracy of the converted DCDB and the "survey-accurate" standard of new survey data.

Determining the accuracy of coordinates

The DCDB NZMG coordinates were converted to NZGD 2000 coordinates with an order of 8th, 9th or 10th in the initial population of Landonline. This order signifies the accuracy of the coordinate and is found in the crs_coordinate table cor_id field (linked to crs_cord_order value). These coordinates were used to generate observations between all boundary nodes and are flagged as pseudo (crs_observation.surveyed_class = PSED).

Survey conversion replaced the pseudo observations with their true values from existing survey plans. Conversion also populated additional node, mark, observation and coordinate data. This was in turn used to generate survey accurate shapes for the parcels. In the crs_coordinate table the sdc_status field flags whether the coordinate is survey-accurate Digital Cadastre or not. Survey Conversion, and new plans, generate new coordinates (6th, 7i, 7ii or 7iii order). Not all nodes within SCAs were able to be upgraded due to the underlying data.

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