Development of validation rules to support digital lodgement of 3D cadastral plans

Validation is a familiar topic in computing, generally as a mechanism to protect a database from the effects of inappropriate data with the side effect of detecting some errors. As such, the validation rules are determined from the database schema using well understood methodologies. This paper takes a different view by examining digital validation as one of a set of processes that are designed to ensure that the incoming data (in this case, a plan of cadastral survey) is unambiguous and contains sufficient detail to define the legal spatial extents of a property. This is a complex question, especially since the rules and the decisions based on these processes must be defensible (therefore cannot contain arbitrary requirements imposed by a specific database model). Using the jurisdiction of Queensland, Australia, as a case study, this paper discusses the manual submission and lodgement of cadastral survey plans and the current 2D digital process as precursors to the automatic lodgement of all plans of survey. A set of validation rules is proposed for application to single geometric objects, to the relationship of objects on a single survey plan, and to objects that are independently defined on separate plans. It is asserted that, by the nature of the problem, this set is incomplete and will remain so. However, this research has identified a “checklist” of issues to be addressed by jurisdictions hoping to implement digital cadastral survey plan lodgement. The implications of this work in the context of the broader challenges in land administration and within the topic of 3D cadastral data are discussed.

► We identify the requirement to ensure unambiguous definition of spatial extent.
► We discuss existing validation with a view to extension from 2D to 3D.
► Proposed validation rules may be applied within individual plans or between plans.
► Rules as proposed are critically evaluated.
► A set of critical issues for successful 3D digital survey submission is proposed.