Application of 3D Cadastres as a Land Policy Tool (Land Lines Article)

Author(s): Erba, Diego Alfonso
Publication Date: April 2012

7 pages; Inventory ID LLA120403; English

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Article

Application of 3D Cadastres as a Land Policy Tool

Diego Alfonso Erba

A city's master plan typically describes development goals and objectives through the use of multiple maps and written documents. Most maps and other representations of urban design are built with a two-dimensional (2D) vision and then transferred into regulatory instruments and strategic planning tools. Urban space is treated as being flat and divided up into puzzle pieces such as administrative areas (municipal, rural, urban, growing, expanding, fringe); land use areas (residential, commercial, central business, historic, tourist, informal, recreational); environmentally protected or restricted area (water catchments, floodplains, landslide-prone hills); and other categories.

When urban space is described through digital maps integrated with databases in a geographic information system (GIS), many additional layers of information can be considered in a three-dimensional (3D) platform. However, when real 3D urban space is managed by laws and other conventions based on a 2D vision, the physical and legal cities are operating in quite different and incompatible dimensions. This discrepancy was accepted in the past, when 2D maps were the primary resource available to represent the real city, but nowadays computer graphics can handle more complex objects in space.

Rethinking the legal and economic aspects of urban society by shifting from the traditional 2D vision to a 3D approach will be necessary to develop, implement, and control urban land policies more efficiently. A 3D cadastre is one of the tools that can facilitate that process through spatial databases and representations. The institution of a territorial cadastre is familiar in many countries, but does not exist in the same way in the United States. A modern cadastre is an integrated database system that holds information on land registration and ownership, physical characteristics, econometric modeling for property valuation, zoning, geographic information, transportation networks, infrastructure and services, and environmental attributes, all of which are linked to socioeconomic and demographic information on property owners.

Creating a New 3D Framework
Google Earth has popularized geographic information by allowing users to visualize a virtual 3D location at the desired level of detail and in a global environment. Google Earth and other geographic software can be used quite easily to change the viewpoint of reality. Moving from a top-down view, which shows the city as a flat area, to an oblique perspective permits the viewer to see the relief and height of buildings, trees, aerial utility networks, and other objects in space.

This type of 3D visualization can identify undeveloped spaces, buildings of different heights, scattered suburban housing, structures in isolated rural areas, and precarious slum construction, thus helping to infer changes in land uses. Even when 3D images are represented on a flat screen or printed surface, they show details that are hard to identify in a 2D map, such as shadow movements during the day, views from an apartment window, and spatial relationships between buildings.

The constantly evolving 3D technology is changing the paradigms of urban planning and land policy because it impacts not only how the city is viewed but the way property rights and other restrictions in space are described. As a result, a new urban legal framework based on 3D laws and 3D property registries will be needed to describe objects in space instead of just flat con-tours. The 3D laws affect rights in space, not in a plane of projection, and in this context it will be possible to define 3D land policies.

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