447
ON-LINE INTEGRATION OF PHOTOGRAMMETRIC SYSTEMS AND SPATIAL
DATABASES FOR PRODUCING STRUCTURED AND CONSISTENT DATA FOR GIS
S. Hosseinian, H. Ebadi, F. Famood
Geomatics Engineering Faculty, K.N.Toosi University of Technology, Tehran, Iran - saharhoseinian@yahoo.com,
Iran-(ebadi)@kntu.ac.ir, Iran - farshid_famood@yahoo.com
Commission IV, WG IV/3
KEY WORDS: Integration, DBMS, Photogrammetric Systems, On-Line, Validation
ABSTRACT:
Photogrammetric systems are important sources for GIS databases. Currently, the trend towards the integration of photogrammetric
systems and spatial databases is increased significantly. Integration of photogrammetric systems and spatial databases has great
benefits in which some of them are mentioned here. This integration makes it possible to use information stored in spatial databases
in the process of automatic or semi-automatic data acquisition and updating. It reduces time and costs of producing and maintaining
high quality and up to date information in spatial databases. Also, if on-line data structuring and quality control tools are provided
and applied in these systems, the quality of data will be increased significantly. Quality and consistency of data is very important
due to the fact that it affects reliability of the results of GIS analysis. For avoiding occurrence of inconsistencies and errors and
maintaining the quality of database, on-line data structuring and consistency control must be considered. In this research for
achieving mentioned purposes, on-line integration of photogrammetric and spatial database management systems for producing fully
structured and consistent data has been investigated. In this way, a rule-based integrated system was developed for on-line and
automatic data structuring and applying consistency constraints using object oriented methodology. Results of practical test of this
system have shown that the produced and saved data in spatial databases, by means of this system, is consistent and structured
efficiently. It shows high flexibility in solving different problems. In addition, time and costs of producing spatially structured and
consistent data for GIS applications is significantly reduced.
1. INTRODUCTION
Photogrammetric systems are valuable and important data
sources for GISs. They collect reliable 2D/3D geoinformation
for GIS databases. The trend toward the integration of
photogrammetric systems and GIS databases is increased
significantly and various integrated systems in different levels
of integration have been introduced to the market. Integration of
photogrammetric systems and GIS databases has great benefits
which some of them are mentioned here. This integration makes
it possible to use information from GIS databases in the process
of automatic or semi-automatic data acquisition and updating. It
reduces time and costs of producing and maintaining high
quality and up-to-date information in spatial databases. Also by
using these systems, map generation in different scales would
be possible. If active validating and on-line data structuring
tools are provided and applied in these systems, the quality of
geoinformaion will be increased significantly and the gains of
efficiency become considerably greater. Quality and
consistency of data are very important, because they effect on
the reliability of the results of GIS analysis. However, a few of
the existing integrated systems have tools for on-line and
automatic 3D data structuring and quality controlling. Therefore,
in this research this issue is considered, for this purpose, in the
developed integrated system topological relationships have
been used for detecting and correcting structural and
topological errors. For designing mentioned system, objects and
constraints were modeled according to the system requirements.
In this system, data is structured and consistency of the
produced data is controlled with respect to the stored
information in the spatial database. This process is carried out
simultaneously with data acquisition process and digitizing
features from 3D photogrammetric model. Error detecting
process is carried out and the correction process would be
performed at the same time if it is needed. After these processes,
the produced 3D spatial data will be directly stored in the
database. Errors must not be allowed to be entered into the
database. For detecting and correcting errors and controlling the
consistency and quality of spatial data, consistency constraints
are used. Integrity constraints have been classified to
topological, semantic and user-defined constraints. Since many
of integrity constraints such as semantic constraints are
application-dependent, it is necessary to create new constraints
or change the existing constraints with respect to the application
and then store them in the repository again. So in the mentioned
system, stored rules can be changed or even new rules can be
created by an expert user. After specifying the rules, they are
stored in the database. These stored rules can be used by any
user for different problems but only expert users can change or
create new rules. This makes it possible to use knowledge of
experts that is stored in the database in the form of rules even
by a user without this knowledge.
This developed system can be applied in the process of data
updating, too. In this paper, the design and implementation of
the developed integrated system for acquisition and
maintenance of reliable 3D spatial data is explained. For this
purpose, Section 2 evaluates integration of photogrammetric
systems and spatial database management systems at first. In
the section 3 development of the direct integrated system with
active validation is explained and in the last section conclusion
and some recommendations are presented.