ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
190 
APPLICATION OF 4D AND ASSOCIATED ENABLING TECHNOLOGIES 
FOR URBAN DECISION SUPPORT SYSTEM 
RongLIU 1 ' 2 Penggen CHENG 12 ZhuguoXING 2 Kaiyun LU 2 
1. National Laboratory for Information Engineering in Surveying, 
2. Mapping and Remote Sensing, WTUSM, Wuhan China, 430079; Email: cpg@rcgis.wtusm.edu.cn 
3. East China Geological Institute, Fuzhou, Jiangxi, China, 344000, Email: jr@ecgi.jx cn 
Key words: 4D products, flood risk analysis model, virtual reality (VR), cybercity. UGIS 
Abstract 
With the growth of cities, both in population and area extent appears as an inexorable process. Urbanization has profound impacts on 
traditional urban planning and management. In order to meet the need of scientific management city, the best way is creating urban 
decision support system (UDSS). This paper presents the application of 4D and relevant technologies for UDSS and it contains four 
sections. Firstly, the contents of UDSS are introduced. Some advanced technologies such as 3D city model and cybercity with virtual 
reality (VR) environment for UDSS are outlined. Secondly, traditional urban planning and management bases on two dimensions. 
Problems during the existing planning process arise because of lack of 3D functionalities to analyze and visualize the 2D/3D data. 
However, 4D techniques are Information resources of creating and analyzing 3D city model. The conception of 4D is described. Three 
dimensional digital city model and cybercity constructed using DEM, DOM and UGIS techniques are present. Thirdly, an example of 
application of 4D and associated enabling technologies for UDSS is explored. We create a flood risk analysis model. UDSS preventing 
flood is becoming more and more important. Finally, some conclusions are made, and some 4D techniques application is outlined. 
1.Instruction 
With the growth of cities, both in population and area extent 
appears as an inexorable process. Urbanization has profound 
impacts on traditional urban planning and management. In order 
to meet the need of scientific management city, the best way is 
creating urban decision support system (UDSS). UDSS are 
explicitly designed to help decision makers solve spatial problem 
by providing a flexible and interactive problem solving 
environment (Denshan, 1991). Such environments provide 
facilities for implementing optional actions, goals and evaluating 
the effects of these changes on system performance 
(T.A.Arentze etc. 1994). It has been widely used in geo-analysis, 
resource management, urban planning, transportation, disaster 
decision-making and commerce decision-making, etc. 
information resources of UDSS comes from the following: 
• Total station and GPS collection in the field 
• Existing map digitizing 
• Photogrammmetry and remote sensing 
• Internet GIS and other information 
Computer science, spatial information and relevant technologies 
are foundation of UDSS. Virtual reality (VR) offers new and 
exciting opportunities to visualize 3D urban geographical 
information system (UGIS)data. Makers and users can walk 
through 3D environments, see newly planned buildings and 
appreciate changes in the landscape (figure. 1). To create 
multi-functions UDSS, besides information collection, advanced 
technologies applied become more important. 
The organization of this paper is in the following way; In 
section 2, the conception of 4D is described. Three dimensional 
digital city model and cybercity constructed using DEM, DOM 
and UGIS techniques are presented; in section 3, an example of 
application of 4D and associated enabling technologies for 
UDSS is explored. A flood risk analysis model is created. At last, 
in the section 4,some conclusions are made. 
2. 4D and Associated Enabling Technologies for Urban 
Decision Support System (UDSS) 
2.1 The conception of 4D 
Photogrammetry and remote sensing image has created an 
urgent need for techniques for urban decision system. These 
techniques have numerous applications in urban mapping, urban 
planning, and other geo-information engineering disciplines and 
application. However, traditional urban planning and 
management bases on two dimension. Problems during the 
existing planning process arise because of lack of 3D 
functionalities to analyze and visualize the 2D/3D data. However, 
4D techniques are Information resources of creating and 
analyzing 3D city model. 4D products contains digital elevation 
model (DEM), digital orthophotoquad model (DOM), digital raster 
graph (DRG) and digital linear graph (DLG).They have been 
widely used in UDSS to visualize model and to enhance the 
interaction of the decision-maker with data and image. 
Fig. 1 3D buildings model 
2.2 Procedure of creating 4D 
2.2.1 DTM and DEM creation 
Digital elevation model (DEM) are nowadays-important 
resource for many disciplines and are useful for generated digital 
products such as contour maps, orthoimages, and perspective 
views. The main incentive for the increasing popularity of DEM is 
the ability to generate them automatically from aerial and remote 
sensing image by image processing and matching techniques. 
Digital photogrammetry system (DPS) is main technique for 
creating DEM (figure2) 
2.2.2 DOM creation 
The orthoimage is created based on the DEM and the 
corresponding original image. According to the theory of digital 
orthorectification, the coordinates of the point projected on the 
original image are computed with collinear equations based on 
its ground control points. Height is interpolated from DEM. The 
orthoimage can be created from one or multi-images, and 
resample of gray levels can be gotten by bilinear interpolation or 
other interpolation methods (figure 3). 
2.2.3 DLG creation 
The DLG created based on digital photogrammetric system, 
scanning cartographic digitization (figure 4) and other methods. 
2.3 4D associate enabling technologies for UDSS 
With the rapid development of digital photogrammetry and