532 
Baratin, Bitelli, Bonnici, Unguendoli, Zanutta 
Figure 4: Zabbar Gate, different vector and raster representation methods 
Another example refers to the Floriana area, where an extensive topographic and photogrammetric survey was carried out for the 
whole complex near the casemates of the Ospizio. A topographic network was firstly established with the aim to provide a local 
reference system. From the vertices of the network, the detail survey of the whole complex was then realised (fig. 5); in this case the 
surveyed points coincide with interesting architectural features, and also a number of height points were determined with the aim to 
obtain the altimetrical description of the area. Different quality controls were obviously carried out to guarantee for the accuracy of 
the survey. 
The results constituted the frame to which refer a previous direct survey of the whole complex, and to evaluate his accuracy. 
Figure 5: Main and detail topographical networks, and their use 
to establish a frame for a previous survey carried out by direct measurements 
From the vertices of the main network, some targets on the facades of the casemates were also surveyed, to be used as control points 
for the photogrammetric survey of the buildings. Due to the planarity of the object, this operation was conduced by digital 
rectification, carried out using Rollei MSR software; the figure 6 shows the mosaic of several rectified images. 
Figure 6: Mosaic of digital rectified images related to the Floriana area (without radiometric correction) 
For another part of the complex, showing an high repetitiveness of architectural elements (arches), a test was realised for the 
generation of different products by digital photogrammetric processes: vector plotting, rectification and differential rectification. The 
last two techniques provide photographic products, that can be used by it-self or can be adopted for an interactive vectorialisation. 
The images in this case were acquired by a small format semi-metric camera (Leica R5), and digitised by the Kodak Photo-CD 
system. In the figure 7 some phases of the elaboration are presented: (a) orientation process for the 3D plotting (software Stereoview 
300), (b) plotting of 3D lines and polylines; (c) construction of the Digital Surface Model by a Triangulated Irregular Network (TIN) 
model based on breaklines and height points, (d) orthophoto generated using the TIN model.