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VALIDATION OF AN ANCIENT PERSPECTIVE IN LECCO (ITALY) 
PIETRO BROGLIA n , EVA SAVINA MALINVERNI n , LUIGI MUSSIO 
n Observatory of Brera - Merate 
r) DIIAR - Polytechnic of Milan 
e-mail: eva@ipmtf4.topo.polimi.it 
Commission VI, Working Group 3 
KEYWORDS: cartographic projections, altimétrie mapping, panorama, camera lucida, photogrammetry. 
ABSTRACT: The authors had the opportunity to collect, analyze and compare different kinds of representation acquired 
by means ancient and modem technologies. The idea was born out after having found an ancient perspective, realized in 
the nineteenth century, by means a camera lucida, in the Archive of Brera Observatory - Milan (Italy). To validate the 
accuracy of the panorama, i.e. the capability of this old technique, to obtain a good altimetric mapping, a modem 
solution, like a terrestrial photogrammetric survey, was set up and compared. 
1. ACTIVITIES AND PURPOSES OF THE 
ASTRONOMERS OF BRERA OBSERVATORY IN THE 
NINETEENTH CENTURY 
Thanks to their geodetic and cartographic research, in the 
XVIII century, the astronomers of Brera and the young 
engineers from the University of Pavia (Italy) could 
achieve an accurate and realistic survey of the territory. 
They always used scientific methods and tested new 
technologies, like the "camera lucida”, which is a 
technique of drawing mountainous landscapes more 
accurate than the traditional tavoletta pretoriana. 
The difficulty to obtain these kind of measurements in a 
short time and without a big effort, is clearly shown in 
memories and graphic documentation, collected in books 
of measurements. 
This was the beginning of the modern cartography. In fact 
the survey of the geodetic base - line Nosate - Somma 
Lombardo, and the realization of triangular networks of 
the first and second order of Lombardy belong to this 
period. 
Among the important documents collected in the Archive 
of Brera Observatory, in Milan (Italy), there were some 
important drawings, realized during the geodetic 
campaigns, which provided the altimetric information. This 
remarks that in that period, a graphic representation of the 
elevations was required. In order to obtain the best 
description (survey) of the landscape, the astronomers 
suggested two solutions for the altimetric problem: 
• the realization of an altimetric network, from 
astronomic, surveying and also barometric 
measurements: 
• the description of hilly landscape with the camera 
lucida, remarking the importance of surveying the 
panorama with measurements of azimuth and zenith. 
For this reason, in that period ingenious astronomers and 
surveyors collaborated together with opticians, physicians 
and mechanics to improve new instruments, like the 
"camera lucida". 
2. THE CAMERA LUCIDA 
The "camera lucida", also called "camera chiara", came 
before the photographic system. It was used to copy a 
drawing, to sketch a landscape, to draw a portrait, mostly 
combined with a microscope (Figure 1). 
Figure 1. The camera lucida applied to the microscope 
The camera lucida was an apparatus consisting of a 
Wollaston's prism or mirrors, used alone or applied to a 
vision system (telescope or microscope). It permitted to 
observe, in the same time, the scene and the paper and 
to draw a perspective of the scene with a big accuracy 
and simplicity. In fact the advantage of this instrument 
was the possibility of obtaining a life - size drawing, 
without approaching too closely to the object. 
In the XIX century, the "camera lucida" was also applied 
to the telescope. For example, the Graphic Telescope 
invented by Cornelius Varley (England), consisted 
essentially of a drawing table and a low - power 
astronomical telescope with a mirror at each end (Figure 
2). 
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