Alessandro DE MASI
(Department of Architecture, Built environment and Construction engineering (ABC) – Milan Polytechnic – II School of Architecture, Milan, Italy)

Keywords: 3D City Models, 3D Survey, Gexcel JRC 3D Reconstructor, photo-scanning systems, Multi-representation


The introduction of digital 3D modeling in the field of Cultural heritage enables the use of models as an interface to share and visualize information collected in databases with web-based tools. The 3D City Models generated by means of photogrammetry and laser scanning are used primarily in urban planning and architecture.  CyberCity generates 3D city models semi-automatically from stereo aerial images or laser scanner data with specialized software CyberCity-Modeler that provides easy use of texturing of facades with both terrestrial and aerial images (CC-autotex). With the introduction of CC-VisualStar was developed a photogrammetric workstation with special features for the continuation of the 3D measurement data.
Therefore, the laser scanner at phase difference or at triangulation along with the software Gexcel JRC 3D Reconstructor, and the photo-scanning systems (ZScan and the Z-Map Laser Mencisoftware) or photo-matching have provided a detailed picture of the cityscape; associated then the scanner with photo-scanning techniques, extremely precised orthophotos are implemented in a timely manner considered unimaginable with classical photogrammetric processes.
From the methodological point of view, the research was articulated according to Multi-Representation and evaluation of the landscape consisting of a set of cultural, geometric, morphological and dimensional knowledge for the formation of a digital 3D model all implementable with multidisciplinary themes.
These systems serve also to define the processes of maintaining the historic urban landscape.
In addition, the 3D laser scanner returns three-dimensional models “inspected” with a continuous, acquisition, which highlights a cloud of points evenly distributed over the geometric model.
It is obvious that the process is reversed in the traditional survey with laser technology, as only at a later time and according to the objectives to be achieved, the selection criteria and representation of the data collected in clouds of points that reproduce faithfully small-scale reality are operated.