ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
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MODELING AND LANDSCAPE OF HIGHWAY CAD 
Jiaqing ZHENG, Xi’an ZHAO, Chujiang CHEN 
China Communications Second Highway Survey, Design and Research Institute 
Yingwu Ave.498,Wuhan,Hubei,P. R. China 
cichenCg-public.wh.hb.cn 
Keyword: Integration, Photogrammetry and Remote Sensing, Highway CAD, DTM, Virtual Landscape 
Abstract 
There is plenty of information in the image by Photogrammety and Remote Sensing.. Highway CAD has cried for the support of the terrain 
data and visualization of the design results. The terrain model is formed by constrained delauary TIN(CDT), which considering terrain 
feature and integer modeling. The gross data in the original data can be found and deleted in real time. Highway road design and bridge 
design are both in AutoCAD, and their model are formed with the object of 3D surface. With overlapping the road and bridge model on the 
terrain model, pasting material, texture or surface image, and arranging scene, the virtual landscape of the design road is formed, and 
dynamic scene can be viewed. The integrative technology of Photogrammetry and Remote Sensing and highway CAD has been formed 
by data collection, indoor data processing and highway design with high-technology. The automatization, visualization and integration 
highway survey and design has been achieved. 
1 Introduction 
environment protection factually. Highway CAD has cried for 
the support of the visualization of the design results 
Highway design usually based on 2D terrain maps which are 
produced by photogrammetry. However, a lots of information, 
such as image of the terrain, 3D topographic data etc., has not 
been used fully. It is impossible to design route on mass 
geographic data, because some key-technology, like the 
management, modeling of mass data, are not in practical. 
Modeling of large mounts of data is the jam between obtained 
terrain data and highway design. 
As the rapid development in computer and algorithm, it is 
possible for microcomputer to process and analysis mass 
information. Image is intuitionistic, visual. Highway design 
linking together image can evaluate the design quality and 
2 Modeling 
The terrain model is formed by constrained delauary TIN(CDT), 
which considering terrain feature and integer modeling. The 
mileage of highway project is long, and there is mass 
geographic data in route plan corridor. It is best to adopt point 
insert algorithm requiring less memory to form CDT. Many 
measures, including efficient index mechanism, rapidly search 
algorithm, optimizing algorithm etc., all are in consideration. 
The formed model is less time consumption, high efficiency, top 
quality, net unique (Figure 1). 
Figure 1 constrained delauney TIN(part in one project) 
The software of modeling is developed by using Visual C++ 
and AutoCAD R14 ObjectARX. It receives AutoCAD R14 
entities directly and other format, like NTDFS-DEM, ASCII etc. 
Code mapping table is used, so as to fit different attribute 
coding by different data collector. User can determined which 
element of the terrain to join the CDT construction. 
The construct CDT speed is constant. It has reached 15000 
valid points per second. 
There are many important functions in the software. They are 
model gross snooping, real-time point/line adding, deleting,