International Archives of the Photogrammetry, Remote Sensin g and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
we can construct the entire solar-terrestrial "Digital Space".
With the improvement of science technology, observation
means, kinds of models should become more and more fine,
accurate. And these advanced data models offer more reliable
data for SIS application.
3.2.2 GIS Offers Many Methods to Resolve Problem
Almost all of environment problems relate to space
dimension.(Li.2002) The basic unit composed environment
simulation and other factor correlative with the environment
simulation all have specialty of spatial distributing, and these
spatial distributing effectively influence the environment
elements interactive process and spatial process dynamic
evolvement. And processing to spatial distributing, spatial
relation and spatial process is GIS advantage. The relation
between the environment simulation and GIS is obviously.
Integrating GIS and the environment simulation in the way of
technology, research contents and methods have extensive
application foreground.
At present, some large GIS software Corp. develop many
module of GIS, such as MapX, MapObject and MapXtreme.
(ESRI, 1996) These COM built on the base of OLE, can be
used for any programme language that bear COM technology.
Thus they give all programmers convenience. So applying GIS
into SIS research has feasible technology base and can be
acquired by GIS software level.
3.2.3 The Application of SciV and Graphics technology
Three-dimension visual simulation is a new type of simulation
technology formatted by combining the computer visualization
and systemic modelling technology. Essentially, it uses the
mode of graphics or image to track, calculate and final- process
for the simulation calculation processing. At the same time,
modelling and simulation to objects by this way have the
following benefits, for example, rapidness, high efficiency,
intuitionist and visualization.
Because the data calculated from the solar-terrestrial space
environment elements is huge, these surveyed data can be
calculated to form 2D, 3D or more dimension data sets. This
data sets includes huge complex information that cannot easily
understand and analysis. The visual technology of the data sets
can translate the no-visual information into visualization by the
way of graphics and image, so it opens out the inner meaning
that contained in the data sets.
For visual processing of the data sets, it not mainly refer the
precision image that be fit with the data accuracy, but construct
and render the graphics and image that can easily understand its
regulation or more information. We can observe and analyze
the inner character from the graphics and image. In conclusion,
the essential of visualization is a kind of information simulation.
4. STUDYING THE SUN-EARTH SPACE
ENVIRONMENT BY THE METHOD OF GIS
4.1 The Research Object of SIS
Based on the graphic environment character, the geographic
data mainly is three or more dimension, its database should be
the three dimensional database corresponding (GONG,2001)
The geographic data have many kinds; the natural data includes
terrain, physiognomy, geology, ocean and lower atmosphere
and so on. The anthropogeography includes building, road,
establishment and population. These data have its own character.
For instance, the geology data mainly shows the static three-
720
dimension space, but the ocean data shows the dynamic four-
dimension space.
In the research of SIS, it makes the space environment as the
application background as similar as the ground environment in
GIS. And the Aerospace vehicle, the main object running in the
space environment, is corresponding with the human activity,
the main body in the geographic activity. The aerospace vehicle
runs in the complex space environment. they changes data and
transmits information with the ground control centres through
the space environment. The space environment model's
goodness directly relates the working performance and life of
the aerospace vehicle.
But the research object of SIS is the dynamic four-dimension
time-space data that includes all kinds of aero crafts, space
environment and stars, and it is different from the two-
dimension or three-dimension entity.
4.2 The Approach to Express SIS by GIS
4.2.1 Build “Digital Space” by the way of Digital Earth
The Vice President envisions the Digital Earth as a multi-
resolution, three-dimensional representation of the planet into
which vast quantities of data can be embedded.(A. GORE) A
key goal is to move beyond the current desktop metaphor for
user interfaces into a more natural, immersive environment that
will facilitate navigation and interaction.
The vision looks something like this: Go into virtual orbit
around Earth. Zoom in on any part of the planet and grab a
detailed view of a road system, vegetation and weather, even an
image of a single house or garden. Flick a virtual wrist, and you
can even know the political layout of the community, all in 3-D.
"Digital Space", namely, creating “The space object and
environment more dimension system" and real reproduction of
the space environment and the space objects is similar to
"Digital Earth" in many design idea and technology. But it has
some difference with “Digital Earth” from the research object,
the time-space specialty, the data management model,
framework models, showing and output.
Referring the theory and technology of "Digital Earth" and
considering enough the time-space specialty and data more-
dimension of "Digital Space", we can integrate the entire space
information to create "Digital Space". In this framework, we
study the concept, contents and key technology of “Digital
Space" and the relative theory system.
4.3.2 Organise Spatial Environment Data by GIS Data
Model
The geographic space objects have four kinds of
characteristic;( WANG, 2001) the space situation, property,
spatial relation and time specialty. As to SIS, its objects have
the similar characteristic.
According to the geometry position and space dimension
specialty, the geographic space objects can be classified to five
kinds, namely, point, line, area. surface and volume. In the SIS,
all kinds of the space environment information are mainly line,
surface and volume. Especially, the volume data model is the
main data model in the solar-terrestrial space environment.
The space object's property is the geographic meaning data or
variable related with the space objects. And it used to express
the objects’ inner character and the semantic definition of the
space objects. In the solar-terrestrial space environment, there
are many properties for only one space environment element.
For example, the variables about the upper atmosphere that has
definite spatial position have some properties, such as the
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