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3 EXPERIMENTS WITH THE PROGRAM ARCHIS 
3.1 The available material 
For the described tests four colour photographs were 
used, which were taken with a Rollei 6006 camera and 
cover the sanctuary’s exterior. These photographs, 
together with others not used in the test, have been used 
for the plotting of views of the exterior with the Wild BC3 
stereoplotter and with the Wild Elcovision system (fig. 5). 
Three of the photographs are not taken perpendicular to 
the photographed wall. The coordinates of 19 points are 
known, they were determined by surveying methods and 
used with succes for the above mentioned plottings. 
3.2 The program Archis 
The program Archis is based on a reconstruction of the 
geometric conditions of the view. In every text on 
designing one meets the scheme of definition of the view 
of a building photographed under a certain angle, once 
graphically redetermined the vanishing points of the view 
and after having scaled some element. 
Archis is therefore not a rigorous program; the aim of 
such a software is that of solving in a simplified way a 
series of problems for cases in which the geometries 
adjacent to the imaged object are narrow, and where a 
high plotting precision is not necessary. These conditions 
are often present in the medieval centres of Italian towns. 
Generally it is very difficult to carry out a fast survey of 
views of closely built houses in narrow alleys. Often the 
result is that the survey is carried out using only 
proportions and completion of the designs with drawing 
on the spot. 
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Archis however allows for a simplifyed rectification of the 
photographed image, after it has be digitized. Considering 
the degree of simplification of the problem, an arbitrary 
camera can be chosen for the survey. 
After having carried out the approximate rectification, the 
image must be scaled. For this, it is sufficient to know the 
ratio between two elements of which one is inclined 
horizontally and one vertically. Also in this stage the 
degree of approximation can be considerable. If desired, it 
is possible to use several distances to improve the metric 
qualities of the result. 
After having completed the operation, the image can be 
combined with another in a mosaic, using common 
elements of both images: on the mosaic one can finally use 
a normal editing of vector data like to drawing lines and 
contouring elements and so obtain a sort of plot. 
3.3 The test carried out and the results 
The photographs of format 6x cm? have been printed in 
black and white on a 18x18 cm“ format. These prints have 
been digitized by a scanner of 200 dpi. In total, the four 
.TIF files require about 14 Mb. 
One at the time, on each of the them, one must identify, 
with the help of a simple guiding menu, horizontal and 
vertical lines in order to determine analitically the 
position of the vansihing points of the perspective view. 
An index gives evidence of the goodness of the 
determination which was carried out, which is obviously 
based on a digitalization with a mouse of well pointable 
elements which are with good approximation vertical or 
horizontal. 
  
Figure 5 - The plotting of views of the exterior with the Wild Elcovision system.