This historic document provides information about the lineage of some Landonline cadastral data. The information is as published prior to the creation of Landonline

1.0. Introduction

Under Sec 11 (1) of the Survey Act 1986, the functions and duties of the Surveyor General include:

"(c) To arrange for the maintenance in suitable format of cadastral survey documents and systems of cadastral survey documents and the production of cadastral record maps portraying surveyed boundaries, land parcels, and appellations providing a comprehensive base for integration of land information data and the establishment of geographic based sub-systems"

The DCDB is the digital equivalent of the cadastral record maps. Its functions in support of the cadastral survey system are to provide:

  1. an integrated framework (seamless map) of the current state of New Zealand's land parcels, to support constitutional, electoral and administrative functions;
  2. a spatial index to all survey plans and statutory actions, to facilitate their access (utilising the above "fabric" as the backdrop);
  3. the capability of linking the data required for the above functions with other relevant survey, land title, crown land and Maori land records.

The DCDB is a distributed digital cadastral database for New Zealand, designed as an integrated Geographic Information System (GIS).

The database runs on Sun Microsystems Inc. hardware in a Unix environment using VISION* software from SHL Systemhouse Ltd, Canada. All data is managed in an ORACLE relational database management system.

VISION* provides the tools for data capture through manual digitising of hardcopy records; numeric entry of survey data through a keyboard; editing of captured data; maintenance of the database; and the output of a variety of products.

VISION* also provides a database management system allowing captured data to be held in a continuous map of each Land District, as well as providing data manipulation and inquiry facilities.

1.1. Definition

"The DCDB is a continuously updated database which graphically defines all parcels of land in New Zealand with respect to their geographic location, shape, area, appellation, and street address. In addition the DCDB defines statistical meshblocks, and their derived boundaries."

1.2. Content

The DCDB contains the following data:

  1. A graphical representation of all land parcel boundaries including legal roads, Maori roadways, railways, and hydrographic boundaries as defined on:
    1. the most recently approved survey office plans, Maori Land Court plans and deposited land transfer plans;
    2. diagrams on transfer as recorded in the Land Title Office, where this definition is current and available.
  2. For each and every land parcel, as defined above, the following are recorded:
    1. A standard appellation (legal description). This will be in terms of the `Land Appellation Database' (LAD), or for new transactions since 1 June 1987, the approved simplified land appellation format.
    2. The approved and official area as defined on metric survey plans; or converted from imperial survey plans; or calculated/deduced with respect to balance areas of part parcels.
    3. Reference to the survey plan supporting the definition; or in the case of diagrams on transfer, reference to the transfer document or a Certificate of Title reference defining the sub-division; or in the case of unsurveyed Maori land partitions, reference to the Maori Land Court records which define the partition.
  3. For land parcels that are affected by cross lease plans produced under the Companies Act 1964 and Unit Plans under the Unit Titles Act 1972 for which titles may issue, the appropriate plan reference number is recorded. The boundaries of those flats or units are not recorded.
  4. For land parcels that are affected by notice in the New Zealand Gazette or New Zealand Statutes, reference is included to record the year and page of the gazette notice or the name, year, section and title of the statute together with details as to the purpose for which the land is held.
  5. For all roads, railways, hydrographic features and reserves, the approved name for the respective feature is recorded.
  6. For land parcels which have been assigned a street address the property number and/or the road/street name is recorded.
  7. For all named roads and railways a linear centreline network is created. Note: Road centrelines represent the centreline of the legal definition and do not necessarily represent the existence of physical access or the centreline of the formed road.
  8. The graphical representation of each statistical meshblock and meshblock identifier as maintained for, and used by, Statistics New Zealand for the Census of Population and Dwellings and associated activities. Refer 2.1.2.

1.3. Structure

The database has three major components; a spatial component, which includes all coordinate and graphical information; an attribute component, which contains descriptive information, and information on topology (or connectivity) of the graphical data.

1.3.1. Spatial Data

The fundamental database graphic entity within the DCDB is called a feature. A feature has one or more coordinates, a graphic text string, graphic parameters (eg. text size, justification), system attributes (eg. feature code, layer number, length, system computed polygon area, etc.), and user defined attributes (eg. appellation, plan number, legal area, etc.).

Features are grouped into logical information layers and within those layers are further grouped into networks containing features which are topologically related. Two types of networks are defined, linear and polygon. Topologically joined linear networks provide facilities for analysis such as districting or shortest path. Polygon networks define the relationships between boundary segments or connectivity of features, adjacency to polygons and relationship of an interior polygon centroid to user defined attributes. When topologically correct, analysis of both graphical and attribute data may be displayed. Examples of these networks within the DCDB are the road centreline linear network, and parcel and meshblock polygon networks.

1.3.2. Attribute Data

Attribute data are stored in two-dimensional user defined tables. These tables are maintained in a relational database management system (ORACLE). Information can be retrieved selectively to client specifications through a Geographic Query Language (GQL, an extended version of the industry standard Structured Query Language SQL).

Two types of user defined tables exist, primary and indirect tables. Primary tables contain data directly related to a geographical feature such as a centroid. Within the DCDB primary tables are used to store user defined attributes for parcels and roads. Indirect tables contain data not necessarily related to only one feature and may contain records defining relationships using unique keys from two or more primary tables.

1.3.3. Topology

Graphical, or a combination of graphical and attribute, inquiries or analysis can only be made if topology (or connectivity) is formed on the graphical data. Facilities within the VISION* capture and maintenance software provide for polygon and linear topology to be formed and maintained to ensure that data are topologically correct. LINZ does not warrant that it is possible to form full topology on data, but will use its best endeavours to achieve this if the client needs it. Clients who require topology in the DCDB should advise LINZ prior to supply so this may be formed as topology is not provided in GINA by default.

Topological information may not necessarily transfer between systems during data conversion. However, by maintaining topology within the DCDB, formation of topology on other systems with this facility can be easily achieved with little further work.

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