DETERMINATION OF THE CLEARANCE CHART WITH CLOSE-RANGE PHOTOGRAMMETRY
Pof. Dr. Sc. Á Detrekói, dr. K. Fekete , A. Knyihr
Technical University of Budapest, Dept. of Photogrammetry, Hungary, ISPRS commission V.
ABSTRACT:
The Hungarian Railway in 1986 entrusted the Chair of Photogrammetry of the Technical University of Budapest with
the working up of a clearance chart testing system based on photogrammetrical system. The paper describes the main
characteristics of this system: the photography by reseau-cameras,the calibration of the system, the stereoplotting using
rebuilded, stereo-comparator, the program system of the calculation The system started to work in 1991 on experimental
mode. The first results are suitable, the system insures the required precision.
KEY WORDS: Close-Range, Analytical, Non-metric.
1. INTRODUCTION
In the year of 1986 the Hungarian Railways (MAV) en-
trusted the department of Photogrammetry of the Tech-
nical University of Budapest with the working up of a
clearance chart testing system based on photogrammet-
rical principle.
On the various railways there are a lot of consignments
which are much larger than usual ones. They are even
larger than the theoretical clearance charts.
For the planning of an undisturbed route for these con-
signments we have to know the real dimensions of the
cealrance charts. The procedure of measurement is usu-
ally very slow when using the conventional methods and
is not to be credited. This fact demands for the elabora-
tion of new photogrammetrical systems.
The two main parameters of the evolving systems were:
1., making serial exposures in rapid succession at a rate
of 60km/h; 2., the precision of the points to determine
were characterized by a standard deviation of 10mm.
2. THE APPLIED METHOD
We could hardly ever find in the professional literature
data concerning photogrammetrical measurements. The
Swedish system (Magnussen at al., 1975) is of two pic-
tures, the Danish one (Aaberg, 1978) is based on a one-
picture shot principle. The Austrian system (Presle et al.,
1987) evolved at the same time with ours is stereopho-
togrammetrical too.
For the selection of the applied method we tested a lot
of various metric or nonmetric cameras, photo systems,
methods of taking photographs and processing methods.
The photo systems were to some extent photographic in-
struments (phototeodolites, reseau-cameras, simple ama-
teur cameras), partly CCD-sensors and inpart video cam-
eras.
We compared the one-pictured arrangements to the two
pictured ones. We examined the analog and analyti-
cal photogrammetrical measurements and also tested the
adaptability of digital image processing. Taking into con-
sideration three things: 1., the precission requirements;
2., the sum at the disposal of us and 3., the expectable
conditions of the working we suggested the elaboration
of a stereophotogrammetrical system based on reseau-
cameras. We also proposed the extension of a special an-
alytic system for the measurements and as a mahtemati-
cal method the bundle adjustment. We made the system
suitable for the graphic representation of the results and
also the junction to a special railway information system.
The presentation of the measuring system is separated
into its components or its stages of work.
3. PHOTOGRAPHY
In order to make the photos there was modificated a rail
car, figure 1. This specially rebuilt motor engine consists
of two parts a compartment and a platform. In the com-
partment there are two cameras and the flashes which
serve for the light. The auxiliary machines are there too;
they insure complementary information.
Figure 1. Rail Car
a) Front view
b) Lateral view
control
point
camer as
Lvs rite M
control
point
cameras
