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New perspectives to save cultural heritage
Altan, M. Orhan

CIP A 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
6.2. Protocol
The malt house belongs to an urban fabric which is not dense.
It is thus easy to go around it. That simplifies the convergence
of shots. Moreover the building has some elements which can
be distinguished at the roof level (chimneys, technical
buildings). This is due to its industrial nature. It becomes then
easy to link images of all façades. The virtual building of the
malt house was obtained by orienting images which have
sufficient overlap.
In Reims, the two streets where the survey takes place are
sufficiently broad to allow perpendicular façades shots.
Unfortunately, one of them is partially hidden by two lines of
trees which appear on quite all the images. Interesting buildings
are partly masked. The shot axe of selected pictures is as close
as possible to the perpendicular compared to the façades. This
allows to avoid perspective effects which reduce accuracy.
Virtual model images were oriented in several blocks. A single
image block is not useful because the virtual model is not a
representation of what exists. Moreover it would have been
composed of a great number of images, which would have
complicated the orientation and the handling of the file
(important requirements of material resources). We split the
virtual model according to housing blocks. Five to ten buildings
were included in each model. Some virtual models were made
according to specific needs. It was the case for precise buildings
(a tower, an isolated building). The site is represented globally
only in the 3D model (fig.9).
6.3. Use of the models
Malt house: once all the necessary images are oriented, the
restitution can start. It is not necessary to model all the building.
Figure 6. Malt house: survey plan, the oblique angle, in its
whole, was designed with help of the virtual model.
Only elements which require details must hold the attention.
Ideally, the model should be carried out at the same time as the
representation of the survey. In this way it is possible to put the
model and the plans in interaction. The model is then related to
the plans (fig.6). This is not a goal but a means of perfecting
survey plans.
We found the Reims model useful in the volumetric form for
dimensioning of the built volumes. Numerous exchanges
between Photomodeler and CAD were necessary to build the
3D model, as for the survey of malt house. This project could
have required a textured model, but the principle of the common
reflexion directed us towards more abstraction for the sights of
the project. Concerning the masks caused by the trees, cables
and electricity poles, our solution however consisted in
orienting an image already used in the model after modification
in the publishing software (Adobe Photoshop).
Figure 7. Picture retouch as texture source
The textured model built with Photomodeler uses some of the
pictures as texture source. It is sufficient to retouch copies of
these images (fig. 7), and then to orient them with the same
points as their double. The textured model becomes exploitable
for a meticulous project representation (fig.8).
Figure 8. Reims: retouched image, oriented in Photomodeler.
Architectural photogrammetry, throughout the kind of
information it brings, can be made available to architects, as a
representation means of existing buildings. The contribution of
a virtual model of the context for a project can make it
essential. Moreover, if the architect can get used to this
technique, the right design process is preserved. The point here
is not to conclude on the need architectural design could have
for a tool like photogrammetry but to present how the architect
can possibility use it. He is free to choose his tools depending
on his project practice.
Being an architect and having used photogrammetry as a tool,
it appears essential to us to set up users’ guidelines for
photogrammetry. It should be made appropriate to people
without scientific background. Photogrammetry can become
an effective and helpful tool for the architect if he is able to
manage it.
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