ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS’’, Bangkok, May 23-25, 2001 
412 
multiplied by 2 H after each iteration (0<=H<=1). H is the 
so-called self-similar variable. If let H=1, then the standard 
deviation will be half of its original value after each 
segmentation, which will lead the generated random function 
to change significantly within a local area, so that rich in 
texture. If this 2D random function is added to a curved surface, 
then the texture on the surface is generated. 
Besides, the chartlet of texture can be from a scanned 
image or generated by a graphic package. 
3.2 Problems of application of texture chartlet 
Texture chartlet is used frequently In the whole simulation 
process of lignigication. If all the texture chartlets used look 
like the same in pattern but different in texture, then the 
surface generated by these chartlets will be looked like a 
wallpaper. In order to solve this problem, the material texture 
needs to change randomly. Usually, large bitmap can be used, 
however, to process it requires much computation time while to 
store it needs more memory space. If different chartlets are 
merged with certain proportion or particular noises are added 
into chartlets, it will solve the problem effectively as well as 
operationally. The following figures shown this result. 
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Ti 
J «U 
J • 
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Figure 3 emulational picture of dou-gong 
Figure 4 emulational picture of 
Dou-gong layer(planform) 
£ 
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Figure 5 emulational picture of 
4. Moving control techniques 
All the graphs and images generated up to now are 
stationary. The kernel of our project is dynamic virtual 
simulation, so computer animation technique is a must. 
Though many techniques of animation can be considered, the 
key-frame based method is adopted here. 
Figure 6 emulation picture of bell tower 
dou-gong layer(upward view) 
4.1 Key-frame based animation 
The most popular computer animation technique is based 
on key-frame technique. The core of this technique is to fix the 
so-called key-frames, and then let 3DS MAX software system 
to interpolate to generate those between key-frames. The B 
spline function is used.