Geoscience Reference
In-Depth Information
Different Coordinate System Dimensions
The local coordinate system is a 2D coordinate system, whereas CGCS2000 is a 3D
coordinate system.
Different Coordinate System Origins
The origin of the local coordinate system deviates considerably from the Earth's
center of mass, whereas the origin of CGCS2000 is coincident with the Earth's
center of mass.
Different Precisions of Realization
The local coordinate system lacks high-precision external control, so the long-
distance precision is quite low. The accuracy of CGCS2000 has increased tenfold
compared to that of the current ellipsoid centric coordinate system. Its relative
precision can be up to 10
7
-10
8
.
Impact and Countermeasures of Implementing CGCS2000
The geodetic coordinate system is fundamental to the all surveying and mapping
work. The change or a replacement of a coordinate system involves a many aspects,
but the most immediate consequences will be regarding utilization of the surveying
and mapping data, results, and products under the old coordinate system. This
mainly touches upon the following aspects:
1. Results of geodetic points under the old coordinate system (approximately over
200,000 points)
2. Topographic maps, nautical charts, aerocharts, and cadastral maps under the old
coordinate system
3. Results of urban independent coordinate systems (including coordinates of the
control points and topographic maps)
4. The established geographical spatial data infrastructure and geographic infor-
mation system
5. Gravity anomalies, height anomalies, and deflections of the vertical of other
ellipsoids
6. Surveying and mapping results for special applications
For issues concerning the transitional applications of geodetic results and map-
ping products, the following technical countermeasures need to be taken:
1. We carry out a combined adjustment between terrestrial and spatial networks
and incorporate the geodetic points of various-order networks into the reference
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