CIPA 2003 XIX th International Symposium, 30 September-04 October, 2003, Antalya, Turkey
4.5 Edge effects
Edges. Results for edge detection and cylinder modeling are
shown in table 5. For typical related point clouds see the
uncondensed and updated version of this publication in the
Internet (WWW, 2003).
4.6 Influence of surface reflectivity
The results of the experiments described in section 3.6 are
shown in table 6.
Type
white
90%
white
80%
gray
40%
black
8%
metal
paint
alu
foil
blue
foil
orange
cone
Callidus(l)
0
0
0
0
0
©
©
©
+7
-10
Callidus(2)
0
0
+4
+3
0..-10
0..-15
+5
-20
Cyrax (1)
0
0
0
0
0
0 +10
+22
-40
Cyrax (2)
0
0
0
0
0
0
+ 17
-70
S25
0
0
0
0
0
0
0
0
GS 100
0
0
0
+8
0
0
n.a. u
0
Riegl Z210
0
0
+ 13
+3
O
©
©
0..-250
0
-100
Table 6: Distance correction in mm due to different surface
materials. Positive sign = Distance is measured too short as
compared to white surface.
J Scanner did not record any points on this surface
4.7 Environmental conditions
All tests were conducted under favorable conditions, predo
minantly inside of buildings.
4.8 Specifications and considerations besides accuracy
When choosing between different laser scanners, accuracy is
not the only fact that should be considered. Selling prices are
important and may depend on different specifications. Support
and warranty conditions differ considerably! It should be
checked how often the instrument has to be calibrated, where
this has to be accomplished, how long this will take and what
kind of expenses (service contracts, transportation, fees) this
will cause for the user.
The quality of the included scanning software has to be
considered, and it should be decided if modeling software has to
be purchased separately from other companies (Boehler, Heinz,
Marbs, Siebold, 2002).
In the following tables the authors report some major
advantages and disadvantages of scanner hardware and scann
ing software. This is based on experience and subjective im
pressions and not on systematic research.
Type
Callidus
Very large field of view.
Cyrax2500
Good accuracy. Good software for registration.
S25
Very high accuracy for short ranges.
GS 100
Large field of view.
Riegl Z210
Very high ranges possible.
Table 7. Major advantages of some laser scanners.
Type
Callidus
Very poor vertical resolution (0.25°)
Cyrax2500
Small scanning window (40° x 40°)
S25
Does not work in sunlight. Not suited for long ranges.
GS 100
Large noise.
Riegl Z210
Poor accuracy.
Table 8. Major disadvantages of some laser scanners.
5. CONCLUSIONS
Laser scanners show considerable errors under certain condit
ions. Although the absolute accuracy is not of much importance
in many applications, the resulting strain between neighboring
points can be cumbersome when surfaces have to be modeled or
when small details have to be detected. The results of our tests
may help the producers to compare the performance of their
instruments to those of their competitors. For the users this
publication and the associated web site (WWW 2003) may help
to select the appropriate instruments for their projects.
6. OUTLOOK
With the targets installed at FH Mainz, the authors are trying to
test as many types of scanners as possible. Users and
manufacturers are invited to have their instruments tested.
Details can be found in the Internet (WWW, 2003).
7. ACKNOWLEDGEMENTS
We would like to thank all institutions who brought their
scanners to Mainz for testing. The tests are part of a research
project “More efficient documentation in architecture, cultural
heritage conservation and archaeology using 3D scanners“
funded by the German Federal Government (BMBF) in its aFuE
program (grant 170 26 02).
8. REFERENCES
Balzani, M., Pellegrinelli, A., Perfetti, N., Uccelli, F., 2001:
A terrestrial 3D laser scanner: Accuracy tests. Proc. 18 th Int.
Symp. CIPA 2001, pp. 445-453.
Boehler, W., Heinz, G., Marbs, A., Siebold, M., 2002:
3D scanning software: an introduction. Proc. of the CIPA WG6
Int. Workshop on scanning for cultural heritage recording.
http://www.isprs.org/commission5/workshop/
Boehler, W., Marbs, A., 2002: 3D Scanning instruments. Proc.
of the CIPA WG6 Int. Workshop on scanning for cultural heri
tage recording, http://www.isprs.org/commission5/workshop/
Johansson, M., 2002: Explorations into the behavior of three
different high-resolution ground-based laser scanners in the
built environment. Proc. of the CIPA WG6 Int. Workshop on
scanning for cultural heritage recording.
http://www.isprs.org/commission5/workshop/
Kern, F., 2003: Automatisierte Modellierung von
Bauwerksgeometrien aus 3D-Laserscannerdaten. Geodätische
Schriftenreihe der Technischen Universität Braunschweig, Nr.
19, ISBN 3-926146-14-1
Lichti, D.D., Stewart, M.P., Tsakiri, M., Snow, A.J., 2000:
Calibration and testing of a terrestrial laser scanner. Int. Arch,
of Photogrammetry and Remote Sensing, Vol. XXXIII, Part B5,
pp. 485-492.
Lichti, D.D., Gordon, S.J., Stewart, M.P., Franke, J., Tsakiri,
M., 2002: Comparison of digital photogrammetry and laser
scanning. Proc. of the CIPA WG6 Int. Workshop on scanning
for cultural heritage recording.
http://www.isprs.org/commission5/workshop/
VDI/VDE Guideline , 2002: Optical 3-D measuring systems/
Optical systems based on area scanning. Beuth Verlag GmbH
Berlin.
WWW, 2003: http://scanning.fb-mainz.de and
http://www.i3mainz.fh-mainz.de
