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Title
International cooperation and technology transfer
Author
Mussio, Luigi

120
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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