The 3D model with the textural data is visualized in fig. 2.3. As
it can be seen, the model is free of distortions since the
photographs of the object were corrected for the image
systematic errors, which had been determined in a'priori
calibration.
The model of the second object — the elements of the old
building was compiled for the purpose of the renovation. The
photographs were taken with the digital camera Nikon E 990.
After — pre-correction. for the image systematic errors the
programme PhotoModeler was used for the reconstruction and
modeling. In fig. 2.4 the modelling of the part of elevation and
the stairs are presented. Figure 2.5 shows how the reconstruted
model can be used for checking and updating of the existing
architectural documentation (plans).
meam Eris fo ee Riester 1]
BER a
Fig. 2.4 Modeling of the stairs
Boii AU KEN
Window
f
Bf AG EE {| Ea Windonn Cormandes 8.50. [8% ProtoMadeter Pro: in. : BE me
Fig. 2.5 Check and update of the existing architectural plan.
3. DETERMINATION OF THE SHAPE OF AN OBJECT
BY GENERATION OF THE SURFACE MODEL.
Modeling of 3D surface requires the determination of a large
number of points which describe its shape. It means that the
Digital Surface Model of the object has to be generated. As
mention in the introduction, there are many applications where
close range photogrammetry has been useful for generation of
DSM for various objects having different size and shape. The
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
444
digital methods based on digital acquisition and processing
systems have increased automation and speed of the process,
The accuracy depends on many factors but mainly on the scale
of the images and texture of the surface. When the object has
the poor texture and therefore the stereoscopic measurement is
difficult, the object should be pre-targeted. Various means of
the signaling have been used dependly on size of the object and
system for image acquisition. In this paper two experiments
concerning two different types of the object and two methods
used for DSM generation will be presented.
The first experiment is concerned with the determination of the
digital surface model of the small archeological detail which is
the part of the broken statuatte. The aim of this experiment was
to check what conditions have to be satisfied to achieve the
required accuracy of parts of milimeters for the measurement of
the shape of such type of sample. The 3D object has size of
about 0.20 meters in X and Y directions and about 0.05 meters
in Z (along the optical axis). Since the object had very poor
texture without the clear natural points and structural features
and the object size was small therefore the optical means of
points’ targeting was applied. The archeological detail was
located within the stable 3D frame with 16 control and check
points which have been used for orientation and check of the
accuracy of the photogrammetric compilation. The coordinates
for these points in the reference coordinate system were
measured by the precise surveying method with accuracy of +
0.3 mm. The light grid was projected into the archeological
detail to enable the measurement of the surface of the object.
The stereo images were taken by the Olympus Camedia C-
2500L digital camera from 1.6 m distance with the
base/photographic distance ratio about 1:3 (fig. 3.1).
Fig. 3.1 Stereo images of the archeological detail located
within the frame with control points.
Before the reconstruction of the photogrammetric model the
image coordinates of all points were corrected for the image
systematic errors which had been determined together with the
parameters of interior orientation in a’priori calibration. The
model reconstruction and sterco digitalization of the surface of
the detail, described by 860 points, was carried out with the use
of the SSK package of Z/I Digital Imaging system. The
accuracy established on the base of the check points was
for X and Y + 0.4 mm and for Z + 0.5 mm. The 3D digital
surface model of the archeological detail is shown in fig. 3.2.
This experiment, which was carried out as the MSc diploma
(Wojtowicz, 2004), is the initial approach within the new
research project in the Department of Photogrammetry,
Warsaw University for Technology. The aim of this research
project is to use digital close range photogrammetry for study
of the parts of the broken archeological small findings located in
various Museums to fit the corresponding parts of the same
object. The initial experiment in this area has showed the
possibiility to achieve the required accuracy of 0.5 mm for the
Internati
pun
DTM ©
Howeve
measure
Fig. 32
The sec
moire fr
spinal d
within
Photogr
already
(Zawies
moire fi
phase st
moire {|
approac
as the
variatio
(Zawies
element
done. Fi
human
around
determi
method
analytic
the use :
Fig.
