ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
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Figure 4 The virtual landscape of one interchange 
modifying, moving, attribute editing, boundary triangular 
clipping, etc. 
Highway road design and bridge design are both in AutoCAD 
R14. There are three kinds of model in AutoCAD R14, which 
are frame model, surface model and entity model. The shape of 
subgrade is irregular. It is suitable and reasonable to adopt 
triangulation to represent the surface of the subgrade. Road 
and bridge surface model are formed with the object of 3D 
surface. 
An interchange is consisted of by multi-camp. The junction 
modeling can be constructed by merging 3D surface vertex, 
splitting 3D surface. 
Figure 2 subgrade modeling 
Figure 3 merged model 
A project contains many kinds of model that is independency 
each other. Each kind of model may have multi-model. Those 
models may be terrain model, subgrade model, etc. It is 
important for the project to manage the model, so that 
embedding, intersecting, merging process among the models is 
carried out efficiently. 
The integration model can be constructed quickly by using local 
updating and optimizing algorithm (Figure 3). With maintaining 
the topo-relation, its operability is the same as the original 
model. For the special case, the bridge model is inserted as an 
entity. In the new model, the profile and stream line can be 
calculated, the value of the height can be interpolated. The new 
model can even be overlapped with the other model to form 
another new model. 
3 Landscape of design 
The virtual landscape technology is one of high-tech scopes of 
combining graph and image technology to human perceive 
theory. It produced a visual sense by using computer, including 
perceptive environment of hearing, touching and smelling. The 
highway designer has earnestly long for the virtual landscape 
of the project produced by integrating geographic spatial data 
with integration model of design. 
Highway virtual landscape real-time roaming system bases on 
digital image, digital terrain model and highway design model. It 
is vivid, stereo and alternate system. By pasting material, 
texture or surface image, and arranging scene, the virtual 
landscape of the design road is formed, and dynamic scene 
can be viewed(Figure 4). The attribute of highway design can 
be also inquired by multimedia. It provides an intuitionistic, 
stereo and dynamic impression to designer. The quality of 
design and the relationship between design and environment 
protecting all can be evaluated.