International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
development. Therefore simple procedures for manual
acquisition on a stereoplotter integrated into a CAD are of great
importance [4]. Capturing of DTM and 3D object data will be
done simultaneously.
The usage of existing data generally captured for other purposes
(e.g. maps, etc.) is very difficult. In most cases those data are
stored in two dimensional GIS. Therefore additional
information such as 3D topology, elevation, etc. is required.
Inconsistency of those data sets presents other big problem. This
is caused by data acquisition using different methods at
different epochs for different purposes.
Modelling
Many buildings (especially in suburban areas) are of simple
shapes. In this case it is sufficient to digitise roofs only. Walls
can be computed from data for roofs (eaves) and DTM .
Fig. 2. Building modeling by roof and terrain data
Three dimensional triangulation algorithms with geometric
constraints are necessary for automatic generation of geometric
primitives.This method is used to model details within roofs.
There are similarities in some buildings and it is, therefore
possible to prepare standard buildings same topology. Lang et
al. (1995) proposed a method for semi-automatic topology
building [5]. Digital photogrammetric methods such as edges
extracting or matching might be extended to 3D- topolog
matching [1].
Information Management System
For urban information system in citywide, with several types of
building numbers with a many thousands of each type and
several thousand digital photos and associated control data, a
database system is necessary to manage all these data.
This information system should handle all relevant data and
areas, such as :
= Aerial images
(orientation, etc).
= Digital terrain model (DTM).
= Digital building model (DBM).
including image properties
Implementation of Photogrammetric Digital
Workstations in Cadastre
The digital photogrammetric methods for data processing
provide retrieval and storage of information in a form
protected against ageing decline. These methods provide
opportunity for operative efficiency of work, and assist the
implementation of new techniques in the organisation of the
technological process. I n addition to the foregoing, some
capitalise an other advantages, related to the use of
computer systems for the facilitation of the connection to
GIS, options for easy data editing in case of errors and
options for restoring history state of data processing. The
main reasons that have hindered the implementation of the
digital photogrammetric methods are justified by the
necessity of storing and processing large data volume,
related to the digital presentation of images which secure
acceptable accuracy. The development of computer systems
which have to comply with the aforementioned
requirements at an acceptable power/price ratio makes it
possible for these to be used as a basis for the development
of the contemporary photogrammetric workstations,
implementing digital processing of images.
Methods for Updating Digital Maps and GIS Databases
of Urban Regions
Owing to the continuous developing of the GIS incurs an
increased demand of methods for updating maps by means
of their implementation. The demand for better and updated
map data is considerable. The standard technologies for
updating maps are insufficient to satisfy the increased
demand [6], incurred both in terms of the contents, and of
the database structure. The brief description of the problems
which occurs in these types of activitics relates to the
existing priory developed digital map data that should be
converted from the originally compiled data files into
special data files, compatible with CAD and/or GIS
software environment. Throughout the process of
conversion, data may be lost, misrepresented or improperly
classified. By means of creating photogrammetric files the
opportunity for viewing the map history is increased. Slides
of the new topographical survey and then superimposed on
the map. In order for the map to be able to comply with the
requirements, the data are presented by means of
stereoscopic photogrammetric model (in other words data
processing is facilitated by means of analytical stereo-
plotters), whereto are added subsequently the height values.
The services and/or the companies dealing with map
processing encounter the following problems:
e Updating the sources of digital data
« Converting in a format, which is suitable for the
new objectives of the system.
e Creating GIS database, on the grounds of newly
developed digital files.
Following the process of gradual change from analogue to
digital technologies, typical of the last two decades, the
customers and providers of digital data successfully
implemental up-to-date computer technologies. The
analysis of the processes of digital mapping, typical of the
past ten years comprise restrains in the data acquisition in
compliance with the data processing capacity of the CAD
systems. The large-scale maps of the urban regions (1 :2000,
1:4000) are generally presented as “CAD maps’, and are
used mainly in graphical representations, survey and town-
planning, and some other basic engineering tasks [3], [7]. In
the last few years they are completed by the implementation
of contemporary CAD software and modern GIS. In the
development of the present maps, the issues like break lines
in relief, congruence of angles are not as important as
mentioned parameters are in the present GIS environment
for making precise topological database for buildings. The
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