bul 2004 
GM. 
and GIS. 
) Live 
ty. In 
k, 
quality: 
'sented 
ing 
(1), pp. 
m 
002. 
the GIS 
n. In: 
Modern 
2003. 
acts on 
niversity 
sed 26^ 
in 
mation 
sity of 
iptation: 
al 
  
GENERATING PRECISE AND ACCURATE 3D CITY MODELS USING 
PHOTOGRAMMETRIC DATA 
O.Emem*, F.Batuk, 
YTU, Division of Photogrammetry and Remote Sensing, Besiktas Istanbul, Turkey- (oemem, batuk)@yildiz.edu.tr 
Comission IV, WG IV/6 
KEY WORDS: Photogrammetry, Three-dimensional, Modeling, Surface, Visualization, Rendering, Virtual Reality 
ABSTRACT: 
This paper presents a study, which aims to generate 3D city models from existing 2,5D maps. A 3D city model is generated via CAD 
software using the existing photogrammetric 2,5D maps of a chosen pilot area. 3940 buildings, 8000 trees, 810 streetlight lamps are 
modeled in the scope of the project. Two 1/5000 scaled orthophotos are used for visualization of the surroundings. In order to reach 
the high vertical accuracy for buildings, extra editing processes are applied to the all buildings in the project area. Therefore, the 
vertical errors of buildings were corrected on 2.5D photogrammetric maps. Finally a precise and an accurate 3D city model of 
Besiktas Region is generated and converted into VRML. Using VRML format, it is also possible to visualize and animate the 3D city 
model on the internet. 
1. INTRODUCTION 
Developments in computer technologies supplies us new 
tools, which can be used for administration, planning, 
applications and making things easier in daily life. 
Furthermore these tools are used to increase the quality of 
daily life and to save the nature. The names of these tools are 
CAD, GIS, GPS, laser scanning, radar, digital 
photogrammetry, 3D city modeling from the point of view of 
measuring, evaluation and presentation. These tools have 
been developed since 1960's Instead of using the hard-copy 
maps, new technologies such as visualizing the 
improvements of city on the display and having a tour on a 
3D virtual city make things easier for architects and city 
administrators, and these abilities let them decide effectively 
and consistently. 
While the applications in digital environment were 
investigations of possession, taxing etc. in 80s; those 
applications were moved to planning and preserving habitat 
in 90s. Nowadays it is possible take a tour around cities in 
virtual reality models, and those models give opportunity to 
make measurements and to design new concepts. 
The 3D city models, which generated by different methods 
can be transferred into GIS easily and used as a base for GIS. 
In addition, it is possible also to make queries on the 3D city 
models, and these 3D city models can be published on 
internet for civilian users (Zlatanova, 2000). 
Nowadays, 3D city models are generated using 3 main 
approaches: automatic, semi-automatic and manual. Thus, 
existing 2D and 2.5D maps are bases for semi-automatic and 
manual 3D city model generation. 
Photogrammetry is an appropriate tool to provide information 
about man-made objects, vegetation cover and the 
like(Gruen, 1999). Photogrammetry and digital image 
processing techniques play important role to make 
visualization technology practical and cost effective. In the 
3D city modeling, simulation is done by using true 
information via photogrammetry. Photogrammetry appears to 
provide the only economic means to acquire truly 3D city 
431 
data (Fórstner, 1999). By means of true information in the 
content of the precision and accuracy, the 3D city models can 
be used for simulation and analysis from visualization and 
animation (Emem, 2002b). 
In spite of high vertical and horizontal accuracy of 
photogrammetric maps, it is not possible to use them directly 
in the 3D city modeling. Especially the buildings on the 
digital maps have some vertical errors, when we examine 
them from the perspective view. Hence, these perspective 
errors should be edited before using them in the 3D city 
models (Emem, 2002a). 
In this paper, a manual 3D city model generation using 
existing 2.5D maps project is presented. But this paper 
mainly focuses on editing the height differences on buildings. 
2. METHODOLOGY 
In this study, some certain methods are applied for the 3D 
model generation as follows: 
e Examining of 2.5D maps for elimination of the data 
which is not used 
e Generation of DTM 
e Editing the vertical differences of the buildings and 
solid modeling of buildings 
e Preparation of the 3D cell libraries and locating 
them on DTM 
e Visualization 
e Virtual reality on the web. 
The modelings of roof of the buildings are not aim of this 
study. Because, modeling of the roofs requires extra data, 
which does not exist in the 2.5D photogrammetric maps. 
3. DATA FOR THE 3D CITY MODELS 
The 3D city models contain data, which is related to the 
spatial objects. Those objects might be located over the 
surface, on or under the surface, and those are includes the 
details, which has certain shape and location. Those objects