structure of height database - projects to the 50x50 grid
network and include the covering information.
The user environment integrate the height, the vector
covering and the raster covering database constitutes as
a complex unit. Their formation's aim was to give a
suitable base to the different government and technical
tasks.
2. New technical possibilities
The new application areas increased the requirements of
the data quality and information complexity. For global
geographic modeling and analysis the airborne and
satellite-born sensors provide much primary data. In the
last decade drastically increased the hardware
performance, the memory and secondary storage
capacity. The remote sensing and the digital
photogrammetric methods become practical parts of the
industrial data capturing and analysis production
technologies.
The new technical developments give a chance to
integrate the remote sensing and digital Photogrammetry
in the GIS applications.
In our case we analyzed the following issues:
- merging remotely sensed data, digital photogrammetric
images and data from other sources
- data acquisition and processing of huge amount of
image information
- image classification based on available land cover
database
3. Proposed technologies
3.1. Hardware background
In the TU. of Budapest an Intergraph ImageStation
Digital Photogrammetric Workstation was installed in
1995. The configuration give a possibilities to solve the
secondary data entry (manual digitizing, scanning),
image processing, digital photogrammetric stereo
compilation and analysis tasks. The Weitek graphic
board and the real-time JPEG card give a possibility to
solve the real time image manipulation problems.
3.2. Software background
The Intergraph ImageStation is a spatial 3D Digital
Photogrammetric Workstation with a standard UNIX
based operating system (CLIX). On the ImageStation the
MicroStation (Bentley-Intergraph) as the standard graphic
engine and the Modular GIS Environment with ORACLE
database management system ( with input, management,
analysis and presentation modules) as an application
software can be used.
The digital photogrammetric and remote sensing modules
embedded in the standard graphic engine.
3.3. Revision and updating of the data base
The following methods was tested as 'real production’
technologies.
Application of Landsat TM images with unsupervised and
supervised classification the interpretation of the different
covering types: river, road, meadow, low vegetation,
water surface, low-medium-high vegetation, low-medium-
high buildings can be solved.
The result is excellent for the 50x50 m raster database,
but the high precision vector database required more
precise technology. The original vector database was
derived with the manual digitalization of analog maps.
The high resolution applications (GSM telecommunication
planing) required 3D object database. The 2D planimetric
mapping object can be get the elevation information with
a simple interpolating technique based on the 50x50m
DTM database. After these elevation interpolation step the
derived 3D element can be superimposed in the digital
photogrammetric images.
In the same graphic environment the operator can be
modified, updated the vector database and real stereo
photogrammetric observations can be used to stand up
the 3D object database.
A quite efficient and simple method the mono-plotting
technique. With application of aerial photographs and the
DTM data base in a low-end environment can be solved
the database updating. The first case use contact copies
of the air photos take to a digitizing tablet, the DTM
database and the orientation parameters of the images.
After the orientation of the contact copy a common
digitizing table the required revision task can be done by
real-time projection of the image coordinates to the
ground. With a simple 2D device we can get precise 3D
coordinates of the objects. The self-developed mono-
plotting software used the MicroStation as a graphic
engine.
The second case of monoplotting use the rectified ortho
images. With applications of the ortho images and the
DTM data base 3D data capturing can be done.
4. Data quality
Generally in a GIS the final quality depends on source
quality. Four aspects of data acquisition comprise the
criteria for selecting data quality (Bernhardsen, 1992):
(1) need,
(2) costs,
(3) accessibility,
(4) time frame.
In the project the data quality was determined in an
iterative process, where the possible technology of data
acquisition and the data quality were analyzed.
The needful quality of the Land Cover Telecommunication
Database can determined by the analysis of wave
propagation models. It is necessary to distinguish
between two cases:
-the radiation of the waves in all directions ( isotrop case),
the radiation of the waves between two
telecommunication stations (anisotrop case).
In the second case it is necessary higher data quality
than in the first case. From economical point of view it is
better the realization of the Land Cover
Telecommunication Database only for the first case. The
220
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996
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