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Title
New perspectives to save cultural heritage
Author
Altan, M. Orhan

CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
473
ation
have
oject of
mesh
of the
all the
lumes of
/een the
emulate
ways of
ument to
Ways of
only the
beams
plitude)
of any
models
images in
The two
/green or
means
aration and
(black
asses)
As said, anaglyphs can easily be obtained from stereopairs of
photographs, but it is also possible to render them from three-
dimensional drawings. Some CAD systems like Microstation®,
allow the visualisation of stereo-images which can show a
realistic three-dimensional simulation of the relief. The interest
of these views lies on the fact that they transmit new sensations
in the observation of objects and they are, without any doubt a
great instrument to call the attention of the public on the
heritage assets.
5.6 Realistic visualization, ortho-rectification.
In the field of
Cartography, DTM are
very often used to obtain
ortho-photographs of the
terrain. These are achieved by
the projective transformation of
differential local areas in one or
several images with the help of a
mathematical frame offered by:
1. That of the
lattice work of the
DTM.
2. Interior geometry
of the camera (lens focal
length and the lens distortion
parameters) as estimated
from the camera
Calibration).
3. The exterior orientation
parameters of the image:
The position vector (3
parameters per image) and
orientation (3 parameters per
image) of the camera at
exposure times.
The objective of differential
rectification is the assignment of
grey/colour values from the
image to each cell of the DTM.
Notice that the need of internal
parameters of the camera is an
obstacle to the use of conventional or non-calibrated cameras.
The ortho-image is a document which has not only the metric
properties of a plan but also the power related to the qualitative
information content relative to a photograph. However simple
rectification would be more advantageous in financial terms if
the object is flat enough. The generation of digital surface
models enables the obtaining of orthoimages but, we must say
that, in general, it is not very profitable.
possibilities that we have managed. There could be many other
applications.
In any case we must admit that the effort needed to get accurate
and detailed models my means of restitution of features without
thematic meaning (breaklines and random spots), makes them
expensive and sometimes unaffordable.
As you all could probably think, all the related possibilities
could be better achieved by the surface models obtained with
laser scanning devices... well, we must agree. But by this time
these machines are not capable to make full-satisfying feature
extraction and still need to work in combination with the classic
more human-guided Photogrammetry equipment.
5.7 Curvature Maps
Curvature of the surface form is a measure of the rate of change
of slopes. This could give us an idea of the distribution of
weathered areas. These are zones of the object where edges are
getting eroded showing different stages of decay or show a
significant loss of high frequency detail.
6. CONCLUSION.
We have widely tested the utility of digital surface models in
the context of Architecture and tried to highlight a few