NUMERICAL INVENTORY OF ARCHITECTURAL OBJECTS
Jolanta Orlinska, Ryszard Preuss
Warsaw University of Technology
Institute of Photogrammetry and Cartography
ISPRSCommissin V
KEY WORDS: Architecture. Technology. Inventory, Non-metric. CAD
ABSTRACT:
This paper presents methodological and technological solutions of the numerical system of photogrammetric inventory of architectural
objects. Applied analytical methods allow to utilise - both metric and non metric - terrestrial photographs and to minimise field works.
Numerical inventory of the entire object is performed in three-dimensional space, within one co-ordinate system, basing on a set of
models which have been reconstructed bv means of photogrammetric instruments, with the utilisation of orientation elements. which are
determined during the process of terra-triangulation. The proposed approach allows to reconstruct the solid body during the stage of
edition, to generate the series of selected graphical presentation of a digitised object and to transfer data to an arbitrary CAD system.
1. INTRODUCTION
Utilization of photogrammetric measurements for creation of
geometrical documentation of architectural monuments is one of the
widest applications of this method for non-topographic purposes. As
a result of conventional, analog approach, a graphical drawing is
obtained; it presents the object pra ection on a vertical plane (parallel
to the main axis of the object facade). which is amended by
horizontal and vertical intersections which characterize the facade
relief. Scale of the created plane (which usually equals to 1:50)
ensures the field accuracy of documented details equal to several
centimetres. Such accuracy may be obtained due to utilization of the
stereoscopic effect, which ensures proper identification and recording
of selected fragments of objects within the space of its reconstructed
model.
Since the middle eighties, the tendency to document such object in
numerical form has been observed. It is the result of introduction of
analytical stereo plotters to the common use and wider utilization of
CAD computer-assisted designing system by architects and
conservators of monuments. Introduction of numerical technique
allowed to register all elements within the selected spatial system. It
allows to fully reconstruct the body of the object and to give up the
idea of conventional, graphical presentation of the object as a
drawing on the vertical plane. which is parallel to particular façades
and amended with selected characteristic intersections. Three-
dimensional registration in numerical form, allows, at anv time, to
read-out, by means of graphical editors, previously recorded co-
ordinates. It is also possible to prepare graphical presentations in
central or orthogonal prg ections, onto specified prqg ection planes.
Together with the introduction of analytical methods. a tendency is
observed to utilize the semi-metric or non-metric cameras for image
registration as well as to limit field works related to measurements of
grids. which are performed for the needs of reconstruction and
elaboration of particular stereogrammes. It is possible due to
common utilization of terratriangulation which determines geometric
features (external orientation) for the network of photographs which
cover the investigated obj ect.
This paper presents methodological and technological solutions
which have been created during the implementation of the research
prgects performed at the Institute of Photogrammetry and
Cartography. The proposed approach allows to perform the global,
numerical inventory of the object. basing on the series of models
reconstructed from the terrestrial metric or non-metric photographs,
by means of photogrammetric equipment, such as the analytical
stereo plotter or the modified precise stereo comparator (used for the
implementation of stereo digitizing). Elements of external
orientation, which were determined by the previous terratriangulation
process, have been directh used for the reconstruction of
photogrammetric models.
2. GENERAL IDEA OF THE SOLUTION
The following objectives have been assumed at the beginning of
implementation of the research prgect, which aimed at design of
technology of numerical measurements of architectural obj ects:
a) the system should allow to utilize metric or non-metric
photographs as raw data,
b) to minimize field works,
C) to utilize surveying measurements in the course of
reconstruction,
d) to utilize the analytical stereo plotter or modified
precise stereo comparator for the needs of
observation and measurements of
photogrammetric models,
€) numerical coding (stereo digitizing) should
enable the explicit transfer of results of
elaboration to typical CAD systems.
A tendency to utilise medium-format cameras for the registration has
been observed for many vears. Such a tendency has been supported
by considerably lower price of equipment. which, at the same time,
has a well developed attachments and additional devices which allow
to optimally select the lens-camera-light source system, in order to
obtain the best possible results of photographic registration of an
object.
However, the utilization of non-metric cameras is connected with the
problem of determination of internal orientation parameters of
photographs which are taken by means of such cameras. In practice.
in order to obtain satisfactory results related to accuracy.
determination of internal geometric features of such photographs is
required during the implementation of photogrammetric
measurements, ie. self-calibration process should be performed
during the elaboration is performed. Thus, utilization of a software
tool should be planned, which would allow to perform the self-
calibration process for non-metric photographs, which are to be used
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
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