(Schertenleib, 1995). If the reflector moves through 3-D
space, the instrument follows and determines
simultaneously the changes in position of the reflector
with a typical accuracy of 0.025 - 0.150 mm within a 2.5
- 15 m working area. The laser tracker allows for on-line
measurement of one object point with a high data
collection rate of about 1000 points per second.
The target of the laser tracker, the cateye, was attached
to the rotation arm. For measuring the circularity of the
track, the instrument was setup in 2 m distance relative
to the arm. Because of the high data rate of the laser
tracker it was possible to determine all points within one
full rotation of the bar. To achieve highest accuracy the
laser tracker was positioned in a stable location.
Number of Circularity Out of plane
points per track (um) (um)
8 8 2
8 9 3
8 8 2
8 9 3
8 8 3
8 8 3
73 8 2
73 6 2
66 7 2
Tab. 7 Measurement results
A series of measurements with different numbers of
points were carried out to show the repeatability of the
results (Tab. 7). The circularity of the determined track
has rms deviations from best fit radius between 6 and
9 um. The rms deviations of all points from the best fit
plane are between 2 and 3 um. The higher accuracy in
recording direction is due to the high precision built-in
laser interferometer.
6. CONCLUDING REMARKS
The on-line and off-line measurement methods for high
resolution motion estimation briefly surveyed in this
paper show some evident differences in tracking speed,
number of points to be measured at the same time,
continuity of the acquisition process, accuracy, etc.. The
laser tracker allows for high precision determination of
only one target but with a high data rate. The
V-STARS/Megaplus system is able to locate highly
precise up to 50 points at the same time. Stroboscopic
and motographic methods - although not working
operational at this moment - record the motion of
several points simultaneously in single images. Thus,
some high resolution measurement systems for object
tracking and motion estimation are available to allow the
user to select the system appropriate to his special
task.
REFERENCES
Baltsavias, E.P. (Ed.), 1995. Proceedings ISPRS
Intercommission Workshop "From Pixels to
Sequences", Int. Arch. Photogrammetry & Rem.
Sensing, Vol. 30/5W1, Zurich, pp. 73-149 (Poster
Session 1: Image sequence analysis and other
algorithmic aspects) and pp. 201-225 (Motion
estimation and tracking).
Brown, J., Dold, J., 1995. V-STARS - A system for
digital industrial photogrammetry. In: Optical 3-D
Measurement Techniques lll (Eds. A. Gruen and H.
Kahmen), Wichmann, Karlsruhe, pp. 12 - 21.
Dorrer, E., Peipe, J. (Eds.), 1987. Motografie. Schriften-
reihe Vermessungswesen Universität der Bundes-
wehr München, Vol. 23, 280 p.
Gruen, A., 1992. Tracking moving objects with digital
photogrammetric systems. Photogrammetric
Record, Vol. 14 (80), pp. 171-185.
Güthner, K., Peipe, J., 1988. Motography and
photogrammetry for the study of movements. Int.
Arch. Photogrammetry & Rem. Sensing, Vol
27/B10, Kyoto, Japan, pp. 246-254.
Maas, H.-G., 1994. A highspeed camera system for the
acquisition of flow tomography sequences for 3-D
least squares matching. Int. Arch. Photogrammetry
& Rem. Sensing, Vol. 30/5, Melbourne, Australia,
pp. 241-249.
Schertenleib, W., 1995. Measurement of structures
(surfaces) utilizing the SMART 310 Laser-Tracking-
System. In: Optical 3-D Measurement Techniques lll
(Eds. A. Gruen and H. Kahmen), Wichmann,
Karlsruhe, pp. 59-68.
474
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
Reverse €
CAD mo
descriptic
can be m:
The digit
Bezier sp
The pape
system ar
1 In
Modern 1
that mak
instance
Reverse «
the proce
ends with
The term
recent tin
describes
conceptuz
Thus, it
involved :
surface re
with an aj
It is inter
also a dif
mathemat
surface re
can also |
data of a
Scenarios.
CAD mo
model. T1
CAD sy
mathemat
