3D Modeling of Buildings: Outstanding Sites

1

Specific Requirements for the 3D Digitization of Outstanding Sites

1.1. The current offer for high-resolution 3D data

In France, the IGN (Institut national de l’information géographique et forestière or the National Institute for Geographical and Forestry Information) produces and maintains the RGE¹ (Référentiel à Grande Echelle or Large-scale reference) over the entirety of the territory, containing four levels of information: a high-resolution orthoimage, an “addresses” database, a georeferenced cadastral map and a 3D topographic database of metric precision containing a description of elements of the landscape, classed according to type. Work is underway on a new-generation RGE, which is more precise and gives better resolution and detail, largely due to the cooperation of a number of stakeholders who collect and manage geographical information throughout the territory.

The IGN is also implementing a semi-automatic production process using high-resolution aerial images (pixel size below 20 cm), which are highly redundant, (significant overlap between images) leading to the production of vector databases in line with the LOD2 (level of detail) specifications of the CityGML² standards. It has been implemented in some large French cities, such as Paris, Nantes, Rennes, Besançon and Marseille. It shows the various districts, roof structures, vegetation and generalized street furniture. This product, Bati3D^® [MAI 04], not only contains a survey of the buildings’ forms (or groups ...