CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
529 
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Figure 1: Photo of the statue Marc Anton which shows 
the complexity of the sensed object. 
to the sensed object of 5m, the average pixel size on the 
object is 3mm. The laser scanner LMS-Z360 allows to cap 
ture 360 ° scans with a vertical scanning range of max. 90 °. 
The measurement rate of this system is 12000pts/sec. For 
the range measurements a pulsed laser beam with a beam 
divergence of 2mrad is used. The sensor provides a single 
shot accuracy of ±12mm. For natural targets range mea 
surements up to 200m are possible. The minimum angle 
step width of this laser scanner is 0.01 ° offering an angu 
lar resolution of 0.002 °. Additionally to the high frequent 
range and angular measurements true color of the target’s 
surface can be recorded by a one pixel camera. The time 
of exposure for this one-pixel-camera is quite short due to 
the high point measuring frequency resulting in an instable 
radiometric quality. 
With the help of these sensors 22 digital photos and scans 
from 10 scanner positions (at every scanner position two 
scans were acquired: one coarse panorama scan (360 ° with 
an angle step width of 0.2 °) and one fine scan (angle step 
width of 0.05 °) of the object) were captured (see Fig. 
2). For the collection of the image data approximately 
one hour was necessary, whereas for the 20 scans the data 
acquisition time was approximately 2.5 hours. For the 
observation of the higher object surfaces 5 photos were 
taken from a ladder and two scanner positions were taken 
using a higher scanner mounting. 
For the identification of homologous points in the 
photo and scanner data 29 signalized tie points were used 
(see Fig. 2). 18 of these points were located on the statue 
(quadratic retro-reflective foil with a size of 2cm by 2cm). 
For the other tie points (11) retro-reflecting cylinders 
(with a hight of approx. 7cm and a diameter of approx. 
5cm) located around the statue were used. 10 minutes 
per signal group were necessary to fix the retro-reflecting 
tie points. For the selection of the most appropriate 
position no complicated analysis is necessary. The aim 
was to place the targets in a way that 4 of them can be 
sensed from every sensor position in order to reduce the 
amount of work for manual identification of un-signalized 
tie points. 
3 HYBRID ADJUSTMENT 
For the generation of a surface model of the whole 
sculpture it is necessary to transform all different sen 
sor observations into one global statue co-ordinate system. 
All observations in the scan data (distance measure 
ments, horizontal and vertical angles) and in the image 
data (pixel co-ordinates) can be described in a local 
Figure 2: Scanner positions (red circles), photo posi 
tions (blue rectangles) and signalized tie points (magenta 
crosses). The three black triangles on the statue are used 
to define the global statue co-ordinate system. 
sensor xyz-co-ordinate system. For the description of 
the observations in the global co-ordinate system the 
transformation parameters of a spatial similarity transfor 
mation of each sensor position must be derived in a hybrid 
adjustment procedure considering individual weights for 
certain observation types (cf. [Ullrich et al., 2003]). 
Such a hybrid chained spatial similarity transforma 
tion considering image as well as laser scanner data can 
be performed with the photogrammetric software-package 
ORPHEUS/Orient ([ORPHEUS/Orient, 2003]) on the 
basis of homologous points. For this aim the measurement 
of tie points in the image as well as in the scanner 
data is necessary. For the adjustment of the data of 
the statue Marc Anton the global co-ordinate system 
was defined with the help of three control points in the 
horizontal plane of the socket (cf. Fig. 2). To achieve an 
unconstrained definition only 6 (defining the translation 
and rotation of the global system) of the 9 co-ordinates 
were fixed. For the definition of the scale of the global 
system the range measurements provided by the laser 
scanner were used. 
The measurement of homologous points was per 
formed manually in the digital photos as well as in the 
intensity images provided by the laser scanner (see Fig. 
3). All in all 33 tie points (29 signalized) were used. The 
measurement of these tie points in the image data as 
well in the coarse panorama and fine scans lead to 1300 
observations for the adjustment. With the help of robust 
estimation and data snooping 62 of these observations 
(mainly from the measurements in the coarse panorama 
scans) were eliminated so that in the final adjustment 
1238 observations participated. The accuracies after the 
adjustment were very satisfying: It was possible to de 
termine the position of the laser scanner with an average 
accuracy of 16mm in X-direction, 19mm in Y-direction 
and 28mm in Z-direction (the definition of the coordinate