ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
89 
'9 
3D) dynamic 
e it in GIS, 
lethods are 
mess of coal 
rce features, 
SIS, different 
i/ith different 
to get and 
ent land use 
and attribute 
and attribute 
apes, DLM, 
e simulation 
ased on the 
IS. How to 
>n-linear and 
Dn statistics, 
GIS can be 
situation, but 
n, especially 
ns, including 
ict on water 
ce would be 
pen to other 
obey certain 
ant to study 
given more 
paid on the 
of subsiding 
land and the dynamic process 
3 SPATIAL INFORMATION COLLECTING BY IDCS 
It is known that mining subsidence can be expressed by two 
means: spatial position (elevation of points) and attribute change 
(the land use and land cover change caused by mining 
subsidence). Spatial information is the basis of all studies, 
especially in GIS applications. 
Nowadays, spatial information about mining subsidence can be 
captured from different means, including field surveying by 
theodolite, level, and Total Station (TS), cubic measurement and 
landscape reconstruction by photogrammetry and Remote 
Sensing, deformation monitoring based on INSAR technique, 
estimation by forecasting model, and dynamic monitoring by 
GPS technique. 
Nowadays, forecasting model and field surveying are the main 
techniques used in practices, but each of them has inevitable 
shortages. Forecasting model depends on the geological, mining 
parameters and mechanical features of rock, and is variable with 
external environment, and some assumptions are applied in the 
model, so its precision is limited, even though different methods 
and theories are used. Field surveying is time-consuming, high 
cost and only results on some observing points can be 
measured, and other points should be interpolated by 
mathematical model, so the precision is not very high. 
With the development of photogrammetry, GPS, and Remote 
Sensing (RS), spatial information of subsiding land can be 
collected by those techniques. Especially Digital 
Photogrammetry System (DPS), GPS combined with GIS can be 
used to realize the integration of information collecting, 
processing, 3D simulation and representation and spatial 
analysis in an uniform system. 
3.1 DPS and its application 
In recent years, DPS has become one of the most important 
means to get spatial information about terrain, landscape, 
building and other entities, and some software such as VirtuoZo 
can be used. Fig.3 is the flow of DPS to spatial information 
collecting of subsiding land. 
Because subsiding land is low in middle and high at edge, it is 
convenient to do the fieldwork of photogrammetry, and some 
work had been done in this field. The further direction is to input 
the images into GIS, process them by professional modules 
compute spatial information and represent the results by DEM 
and contour. 
3.2 GPS and its application 
With its advantages of round-the-clock observation, high 
automation, 3D information collection simultaneously, easy work 
Fig.3 Spatial information collecting and processing by DPS 
and so on, GPS technique has got more and more applications 
in surveying, deformation monitoring and navigation. GPS 
applications to mining areas have already got some progress, 
and one of them is to monitoring and surveying subsiding land 
including its borders and 3D shapes. In GPS applications to 
subsidence monitoring, the most important issue is 
determination of elevation and differences in elevation. In order 
to use GPS to subsiding land monitoring, two schemes can be 
used, which are illustrated by Fig.4 and Fig.5. 
We can know that the Scheme in Fig.4 is based on height 
interpolation and transformation between geodetic and normal 
height and the key is abnormal height, and scheme in Fig.5 is 
take the difference in geodetic height as subsidence quantity 
directly. It proved to effective to use each of the two schemes. 
GPS observing data should be process by special software 
before spatial information is got. Two methods can be used to 
input GPS information into GIS, one is inputting 3D coordinates, 
that is X, Y and Z of each points computed by special software to 
GIS and the other is to develop GPS data processing module 
inGIS and raw observing data is input. At present, the former 
method is used mainly, but with the development of integration 
of GPS and GIS, the latter would be more convenient. 
3.3 Integrated data collecting system and its applications 
Several methods can be used to collect spatial information of 
subsiding land and each has its own advantages and shortages, 
so a useful choice is to set up an Integrated Data Collecting 
System (IDCS) to use the most effective methods for different