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Title
International cooperation and technology transfer
Author
Mussio, Luigi

79
The operative procedure gives the possibility to obtain
horizontal and vertical sections from the model in order
to verify possible shifts from the vertical.
Once we realized the model the operator chooses the
lines defining the geometry of the object to be
represented, and it is always better if the operator works,
as far as possible, with specialists who will use the
resulting elaborates in the following study phases.
Regarding the south prospect (fig. 5) we decided instead,
to apply to a simplified restitution method. In restitution
phase we specifically empoyed the Eclovision system,
while the photogramms work took place with a Rollei
6006 semimetric camera.
The devices carried out in the photogramms taking phase
suited the small film size (6x6 cm), the photosensible
material chosen (Kodakcolor Professional 120 ASA film
and ILFORD FP4 100 ASAQ black and white film), the
camera setting during the photogramms taking (the
direction while taking the photogramms has to be
perpendicular to the object plane); the framing (that is to
say the ratio between formation of the photogramms
taking and the average camera-object distance that has to
be about 1:3).
A correct planning in taking the photogramms was
necessary also to the wideness of the south façade, so that
more models had to be linked together.
In the restitution phase, the Elcovision system uses a
couple of positive photogrammms rightly enlarged (in
our case the employed size was 24x24 cm") and placed
on a digimetre.
It is necessary to remark that among the advantages this
procedure presents compared to the classic
photogrammetry. the taking photogramms position can
be. generally, fitted to the environmental nature, besides
the corresponding points on the two photogrammes have
to be monoscopicallv digitalised by using the graphic
bar mouse, in order to make also possible for the not so
skilled operators the instrumental coordinates knowledge.
Once obtained, the data enter an orientation program that
rcconstrunumerical model of the object we want to
represent.
The outstanding Elcovis system features are the
utilisation of the only monoscopic vision and the
impossibility' to restitute by continuous lines (the
restitution only by points is something possible). This
means the necessity of a correct individuation of the
corresponding points on the two prints, that makes
impossible for example the restitution of points belonging
to curves surfaces or placed in non favourable conditions,
that is in the shade or outside one of the two images.
The system makes a three-dimensional restitution
possible, that is the continuous acquirement of the
coordinates couples and the object lines representation on
the video.
Such an operation is supported by a CAD inside the
program that gives the chance to represent the digitalised
points at the average image scale and to relate them in a
si utable way.
It is possible to choose the ortographic projection plan of
the representation, keeping in mind the three-dimensional
coordinates of the resulted points.
In an experimental way we traced some vertical and
horizontal sections connected to the south façade, having
before chosen the representation ortographic projection
plan (fig. 5)
Fig. 5 - The south prospect of the church
The obtained precision, also verified by the comparison
with the coordinates values of the detailed points, has
resulted between the graphic tolerance values for what it
concerns the prospects restitution.
We noticed a bigger indétermination for the Y
coordinates (depth) values definition. These values
differences has in fact been calculated in 5 cm. We are
obliged to apply to classic photogrammetry for what it
concerns the projection determination and the shifts from
the vertical.
The archaeological survey
The topographic and photogrammetric survey of the
ancient Kastro of Pereia represents the second experience
and in this case the application is in the archeological
field, (fig. 6)
The whole work was performed few years ago with two
different survey's campaigns carried out in Greece and
more precisely in Tessaiia region.
Fig. 6 - The ancient Kastro of Pereia