are stored on CD-ROM. The patches of control points at
the border of a measured block are needed later for attached
blocks which also contain these points. The images could be
used for other projects as well.
5 MANAGING THE DATABASE
The Institute is setting up a control point model database
of the state of North-Rhine-Westfalia for the Survey Depart-
ment. The size of NRW is about 34000 square km, 70% of
this area will be measured. The unmeasured part has no or
not enough control points.
Two main problems have to be solved by the management
software:
1. The programs have to deal with a large number of
coordinate data.
2. Different operation systems (UNIX and MS-DOS) are
used in the production process.
The second problem (UNIX and MS-DOS) can be solved ei-
ther by
e writing interfaces and independent software
or by
e using a general data model with special management
on every system.
The second possibility is chosen because it is more flexible
and easier to handle when using the same data model
everywhere. From the data access point of view there should
be no problem to run an algorithm on different computer
systems when using the second solution.
To implement a unique data model, it would be a good idea to
use a unique programming language which could easily handle
hardware independent and hardware dependent parts. With
an object orientated system one can model the specialization
problem for different operating system with inheritance. C++
is chosen as the used language because it is available on both
systems.
To get an overview of the software system, figure 4 shows
the important classes for the management of the data as an
object relationship diagram [D.W. Embley, 1992].
The common data access is modeled by the abstract template
class TDatalnterface which offers simple declarations of set-
access methods like 'FindFirst()' or 'FindNext()'. On the PC
there exist implementations of these declarations as inherited
classes for sequential data files and arrays. These classes are
also available on the UNIX-system.
At the PC which is connected to the Analytical Plotter P3
only the actual measured block (about 300 aerial images and
750 control point models) has to be managed. But at the
SUN-Workstations all the data has to be accessed. This as-
pect leads us to the first mentioned problem to solve (large
number of coordinate data).
In Table 1 one can see the number and size of the data which
has to be stored. So much of data could not be managed
effectively with simple files or arrays, therefore a database
management system should be used. The data types could
be easily modeled in a relational system because super-
keys already exist and the attributes of the classes are atomic.
222
Image areal
coordinate image
is managed
by /
object is managed control point
coordinate by model
ics "s
is mais M el
by | . TDatalnterface | ^ by
<type>
dé ( A means: 'is specialization of")
Manager<type> Manager<type> Manager<type>
for files for arrays for sql-database
Figure 4: Classes of the management software as an object
relationship diagram
Data Type | Number of data | size of data
image coordinates 270 000 13 MByte
object coordinates 60 000 3 MByte
orientation data 16 000 2 MByte
control point models 30 000 30 MByte
image patches 135 000 33 GByte
Table 1: Amount of data for North-Rhine-Westfalia
In this project the free available relational database POST-
GRES95 is used. POSTGRES95 has an interface for the
programming language C which allows the programmer to
send SQL statements to the database. For each class with
persistent data a table in the database is created. The in-
formation could be accessed via a specialization of the class
TDatalnterface. One can also use advanced features of the
SQL-language.
The production steps 'Measurement of wireframes' and
'Controling wireframes' store and get their data from POST-
GRES95. This management allows to gather information
about the total already measured area.
6 RESULTS
At the Survey Department North-Rhine-Westfalia the module
for the automatic exterior orientation is actually integrated in
the orthophoto production process. The Survey Department
has chosen a photogrammetric system from LEICA called
SOCET SET for their production. AMOR will be run directly
after the scanning process or as a batch process at night for
several images. The database of the control point models is
growing according to the needs of the renewal program.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996
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