platform . In recent years, some thematic model 
have been developed world widely, which have 
acceptable speed and precise, but compared with 
those based on GIS platform, these model have 
some shortages. GIS has great advantages in four 
aspects described below: 
2.1 Material Storage 
Each time when a city revises its master plan, it is 
required to collect a lot of data and materials like 
report , investigation, map, image, captured data , 
historical reference, and so on. It creates new 
from analyzing and 
with the 
requirement to new urban master plan. GIS has 
planning achievements 
arranging these materials and data , 
more powerful function on data base management, 
it can put reference, map and image into classes 
and titlesthen stores them. — When next rang of 
master plan begin, these reference can be regarded 
as valuable historical data, because that urban plan 
always emphasize certain continuity . 
2.2 Easy to Update 
It is more convenient to achieve when existing 
infrastructure change, or some infrastructure need 
to change in the procedure of planning. GIS has the 
like 
and non-spatial information like 
function on fusing spatial information 
coordinate 
attribute, updating and maintaining easily, so it can 
keep data up to date, such as moving location of 
infrastructure , distributing adjustment of pipe net 
and updating attributes of infrastructure. 
2.3 Keeping Graphics and Texts on a Screen 
Non-GIS thematic model always gives number to 
the 
attributes of those nodes and pipes to computer, by 
nodes and pipes manually, then inputs 
Which to achieve the strenuous calculating work . 
Some software ‚which have been developed more 
deeply, also can create reports automatically with 
363 
the given number and output map, but the preparing 
procedure are more difficult and strenuous . Even 
more , those operation are always not satisfied. on 
the contrary , GIS platform has good interface to 
support graphics and texts existing together on one 
screen, and it is very convenient to finish all the 
procedures, just like browse, query, statistics and 
output. 
2.4 3D Viewing 
It can create DEM by using separate elevation 
points or contours on GIS platform, then overlay the 
information of infrastructure on DEM. Now, users 
can observe and measure them from different 
viewpoints, so they can reduce some faults in the 
procedure of planning. for example, whether it 
needs add pressure on the scope with great changes 
of terrain. At the same time, GIS can return the 
information like coordinates of pipe net , elevation, 
length, overlay area and section area to user . 
Users also can create 3D pressure model with 
elevation of infrastructure pressure, then overlay it 
onto existing DEM, view and query the pressure 
and coordinate information at any place. the effect 
is more novel and original. 
Thus, GIS shows more powerful advantage on 
optimal urban infrastructure , and has very wide 
prospects. We'd like to solve the program through 
modeling of infrastructure based on GIS. 
3. ESTABLISHMENT OF MODEL 
Optimal model of urban infrastructure includes 
mainly four aspects described below: 
3.1 Assessment and Forecast of Requirement to 
Infrastructure 
Assessment of requirement is often derived from 
uses, for example living use, industry use,fire 
fighting, afforecast (etc.). The part of living use 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996