' of architectural
nise field works.
sing on a set of
ments. which are
ring the stage of
CAD system.
series of models
tric photographs,
as the analytical
ator (used for the
Xs of external
terratriangulation
econstruction of
TION
the beginning of
ned at design of
iral obj ects:
rric or non-metric
in the course of
tter or modified
or the needs of
surements of
ould
esults of
stems.
e registration has
S been supported
at the same time,
vices which allow
stem, in order to
egistration of an
onnected with the
n parameters of
1eras. In practice.
d to accuracy,
h photographs is
photogrammetric
Id be performed
on of a software
yerform the self-
ich are to be used
for inventory of architectural objects. In the discussed case. it was
decided to use the "ORIENT" system. obtained from the T.U WIEN
within the assistance for the Eastern European countries. At the same
time, in order to publicize the created solution, it was also decided to
elaborate own software package. basing on the condition of
collinearity. which could be used for common calculation. in the
variant wav, the elements of internal and external orientation for the
network of terrestrial photographs. In practice, the "TERRANET"
package was designed and created; its functional features are
discussed in the next section.
The above mentioned software tools also allow to accept the idea.
that during the stage of obj ect registering, it is possible to take many
photographs which cover the entire object, with the assumed scale.
Respective overlapping of photographs allows to perform the
process of terratriangulation, basing on these software tools. and
then, to perform stereo digitising of selected photographs, which
would ensure to perform proper stereoscopic observations and to
maintain the assumed accuracy of object co-ordinates.
Implementation of the terratriangulation process results in maximum
limitation of the number of points required for the ground control
network. Characteristic feature of programmes which are to be
utilized for the needs of the discussed process is the possibility of
simultaneous consideration of surveying measurements. which create
additional equations of conditions.
The calculated elements of external and internal orientation (in the
case when non-metric photographs are utilized) are used for direct
reconstruction of spatial models. by means of photogrammetric
instruments.
Such an approach required preparation of specialised software.
which enables to receive resulting data from ORIENT or
TERRANET packages and to generate - after observation of
fiducial marks (restoration of internal orientation) parameters of
orientation of photographs in a photogrammetric model and its
absolute orientation with respect to the ground co-ordinate system.
In the case of utilization of the analytical stereo plotter, it was
additionally assumed that during the reconstruction of absolute
orientation the following requirement should be met: when the
reconstruction of the spatial model is completed. the measuring
cursor, which is moving in the XY plane of the model. should move
parallelly to the elaborated plane of the fagade of the building.
Such a condition allows to create more convenient circumstances for
the process of stereo-digitising. It has been assumed in the proposed
technology, that the proper elaboration of particular stereogrammes
should be possible on the modernised Stecometer produced by Zeiss.
It has been accepted that the required range of modernisation of this
instrument should include its adaptation to on-line work with a PC
class computer and installation of a stepper motor, in order to
eliminate the vertical parallax in a quasi-continuous w av - this allows
to perform stereoscopic stereodigitizing.
Il was also assumed for the discussed idea. that correct inventory. of
architectural obj ects requires the observations and measurements of
photographs with the utilisation of stereoscopic effect.
It was decided, that in order to ensure the proper transfer of results to
standard CAD software packages. special drivers should be
developed to control the movements of carriers and to process
photogrammetric measurin g data to field co-ordinates. which will be
accessible for selected graphical editors to edit and archive data at the
Photogrammetric station. After comprehensive analysis was
Performed it was decided that the designed drivers will directly
Support the MicroStation system. under which the object
Measurements will be performed.
439
It was also assumed that coding should be fully three-dimensional
and obj ect-oriented.
Acceptance of such an assumption, during the stage of
stereodigitizing. allows to split the information on an object into
layers. thus enabling to simpli possible editorial works during the
creation of thematic maps and presentation of results. Spatial
measurements of particular façades, in a stable. ground co-ordinate
systems. allows to fully reconstruct the body of an object and then to
present it. in an arbitrary - perspective or orthogonal - prj ection.
with an arbitrary orientation of the pra ection plane.
3.HARDWARE AND SOFTWARE
The discussed research project was implemented basıng on the
equipment existing al the Photogrammetric Laboratorv of the
Institute of Photogrammetry and Cartography: the precise stereo
comparators STECOMETER ZEISS and the analvtical stereo plotter
PLANICOMP P3.
Original configuration of the stations using the precise stereo
comparators has been modified. The stations were equipped with
hardware and software elements, allowing to determine and
automatically eliminate, in the on-line mode, the vertical parallax and
to perform continuous registration of the measuring cursor, by means
of the special card of electronic counters. The equipment of these
instruments was amended by foot pedals and touch sensitive tablets
in order to automatize and simplify the process of stereo digitising.
In order to allow for elaboration of terrestrial photographs by means
of the STECOMETER, the software package was prepared which
allows to perform the following tasks: acquire photograph co-
ordinates (TLOWE) in formats which correspond to requirements of
adjustment programmes, the MODEL ST routine which processes
instrumental observations into ground co-ordinate system. basing on
data from the network adjustment. Drivers allowing to perform the
3D stereo digitising process directly in the MicroStation system were
also designed.
Besides, standard software of PLANICOMP P3, the analytical stereo
plotter, was modified and amended with the MODEL ST routine:
this routine allows to create a model basing on terrestrial
photographs and with the use of parameters which are determined
during the process of terratriangulation.
The ORIENT and TERRANET routines, elaborated within the
discussed project, were applied to determine the initial data for the
above mentioned routines.
precise analytical photogrammetric
stereocomparator stereoplotter instruments
TLOWE data acquisition
|
ORTENT TERRANET
L L
MODEL ST MODET, SP
J i
MIGROSTATION
adjustment
model reconstruction
stereoplotting
|
n
Fig. 1 Data flow in the system
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
