bul 2004
igement
er 4 we
/AQS
database
files. For
hould be
building,
here the
ch theme
| dataset
topology
TM and
complex
1agement
ology is
ated and
previous
and their
ed in the
0 project
1 to each
le added
ngs with
nk each
d. Then,
's and to
UserID”
shown.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
EIER v3d
‘Wall Facets
cot
Figure 6. Linking attribute tables.
In Figure 6, owners table is master and the object attribute table
is slave. As seen in the figure, when the user selects a record
from master table, only the related record(s) are selected and
shown in the slave table. In the figure, since the slave table is
OAT table, and since it is linked to geometry, corresponding
building in the render window is also shown with a different
selection color. Here selection color is green as seen in the
figure. With this link, owner table (owner information) is linked
to geometry via OAT table. The link can be constructed double
sided too. This means that, when the user pick an object on the
render window, its corresponding records in the related tables
are also been selected automatically. We provide SOL queries
on every table added to project. For example, one can want to
see a particular owner's building on the screen. In this case user
should write the required SQL query script on the query
window. Then, according to the query result, intended records
are selected with their corresponding geometric objects.
One can easily create a new data table or modify existing
one(s). Tables can be created with another software which
support dBase and Paradox too. Externally prepared data tables
can easily be added to project.
One can query any object by picking it with mouse on the
render window. In Figure 7, a picked object's information taken
from attribute table is shown in an id window.
le) x)
wr stes i woh 5, a 1 Intémot iD. T3
ise
sant) 103
30 Layers List : us Eu ohne fenes 7
Fisote
C On
rof
Wall Facats
F On
con
17742,1060
16604 6000
11865, 2000
8405 4100
Figure 7. Query with picking object
On the id window, items of the OAT table are shown. When
new items are added, they are automatically shown too.
N
Ww
4. DATA SET USED IN 3D-CITY VAQS
For the terrain representation, our tool uses DTM model.
Regular grids or TIN can be used. Our tool can import and
export ArcView ascii DTM file and USGS DTM files. It can
also open x,y,z point dat files and creates DTM with regular
grids or TIN. For TIN generation we use Delaunay
triangulation. Photorealistic texture images (orthophoto,
satellite images etc.) can be mapped on to DTM or buildings.
Our tool can project grids or triangles of 2.5 D DTM to a 2D
plane. Thus 2D GIS analysis can be performed by using 2D
projections. We are still working on spatial 3D GIS analysis.
Our tool 3D-City VAQS can represent every kind of 3D object.
This tool can open and visualize V3D files too. In our tool for
realistic texture mapping, images can also be used.
5. CONCLUSION
With our tool, visualization and query of 3D city models can
be performed effectively. But still it is under development to
provide 3D GIS analysis. We can perform some 3D analysis
such as buffer, clip, etc. at this point. But overlay analysis are
too time consuming without using set theory together with
geometry. For this purpose we are motivated on the description
of 3D GIS analysis in a formalist manner. At this point, we can
perform overlay analysis with complex geometric computations
but still we can not use 3D topological relations effectively and
so these computations are too time consuming. In order to
overcome this problem, we are studying to combine topology
and geometry by the means of set theory.
6. REFERENCES
Aronoff, S., 1995. Geographic information systems:a
management perspective, WDL publications, Ottava, Canada.
Goodchild, M., 1987. A spatial analytical perspective on
geographical information systems. /nfernational Journal of
GIS, 1(4), pp. 327-334.
Gruen, A., Wang, X., 1999. Cyber city spatial information
system (CC-SIS): A new concept for the management of 3D
city models in a hybrid GIS. The 20th Asian Conference on
Remote Sensing, HongKong, China.
http://www.geod.ethz.ch/p02/ general /persons/AG_pub/cc-
sis_acrs.pdf (accessed, September, 2003).
Molenaar, M., 1992. A topology for 3D vector maps. /7C
Journal 1, pp. 25-33
Schroeder ,W., et al., 1998. The VisualizationToolkit An Object
Oriented Approach to 3D Graphics. Prentice Hall PTR, New
Jersey.
Zlatanova, S., 1999. 3D GIS for urban development. PhD.
Thesis.http://www.gdmc.nl/zlatanova/PhDThesis/html/ content.
html (accessed January 2004).
