International Archives of the Photogrammetry, Remote Sensing and Spatial [nformation Sciences, Vol XXXV, Part B2. Istanbul 2004
Figure 5b. Example: Result of rule based aggregation.
4. VISUALISATION
Commercial GIS systems like the used ArcGIS system from
ESRI did not provide standard tools to display and handle
MRDB data. Therefore we have developed at the ikg a tool for
ArcGIS in VBA (Visual Basic for Applications from
Microsoft). The MRDB tool (Figure 6) allows to display all
four ATKIS DLM' s in one overview and the selection and
linking of ATKIS objects. One can select one or more objects in
one of the four DLM's manually or by a query and the
corresponding objects (linked objects) in another DLM will be
displayed automatically.
r- Einstellungen
insteiangs Maps Layers Fields Selection ausfiltern nach
Map 1 3 ;
[select] | DLM1000 z| | ATKIS.BHOLZ. +] | OBJEKTID zi | OBJEKTID Gehe
Map2 | pLm2SO
Mops zi | ATKIS.BHOLZ. x] | OBJEKTID M aum Gihe
Zoom 1222 | Zoom 2751 | Zoom to ATKIS.BHOLZ 250 OBJEK- | Weitere Einstellungen |
r- Ráumliche Abfrage ———————————
SpatRell esriSpatialRelIntersects z]
Where [comme] | ———
RelDef D
Matching (Batch Job) | Manual Matching
Suche mit Linktabelle
Info Schliessen
Suchen N
|start…|ADO: Conn OK
Figure 6. Main window of the MRDB tool.
The connection between the MRDB tool and the MRDB is
based on ADO (Active Data Objects from Microsoft) and
ArcSDE. The technical problem was how to display several
DLM's at the same time in ArcGIS. There are two views in
ArcGIS. The data view which should be used for interactive
processing and the /ayout view which is used to control the map
layout for printing purposes. The problem which occurred was
that the more flexible data view only displays the active data set
(the data set the user can select something). Several windows in
the data view at the same time like a multi document interface
is not supported by ArcGIS in version 8.3. Fortunately the
layout view allows to display several data sets at the same time
in so called data frames. In a data frame one can select objects
also manually and one can control a data frame with a program.
Therefore the layout view is used in the MRDB tool. Figure 7
shows the presentation of the four ATKIS DLM's in the layout
view of ArcGIS.
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Figure 7. Layout view of the MRDB tool.
S. UPDATE
The goal of the WIPKA project is to implement an MRDB to
enable an automatic incremental update process of all
representation levels in the MRDB. The idea is to update only
the lowest level with the highest geometric and semantic
resolution (in our case is that the ATKIS BaseDLM). All other
levels should then be updated automatically at most as possible
to make the data revision process faster and more efficient and
consistent. We are now developing a message passing system
which will allow us to control the update process by
propagating the changes through all levels according to the
stored MRDB links and to trigger appropriated generalisation
operators. We are in the early stage of these project, we can
only describe the rough concept which we want to implement.
An MRDB can be seen as a directed Graph (Figure 8 shows this
situation schematically) which provides information about the
relationship between objects. These relationships can be used to
propagate updates bottom up through the representation levels.
In our concept we define three main types of update events
which are propagated through the network:
e Insert: A new object was created.
e Remove: An object was deleted.
ged.
ES
c
e Change: An object has chan
These changes can be divided up in:
e Change Attribute: Only attribute values are changed.
e Change Geometry: Only the shape of the object has
changed.
e Change Attribute and Geometry: The attribute values
and the shape have changed.
After the update process of a lower level is completely finished
all changes are propagated to the next level according to the
stored links. The update propagation has to be understood as
calling an appropriate gencralisation method for the linked
object at the next level. For the update process the system will
provide a set of generalisation operators which are selected by a
rule based system. That means the user has to maintain a set of
rules which describes what operator should be used under
certain conditions. These conditions are the type of the update
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