Geoscience Reference
In-Depth Information
Fig. 7 Coordinate bias in the
relative positioning
4.2 Confusion and Mismatch with Base Map
It is recognized that many social and economic activities such as navigation, civil
engineering, oil and mineral exploration, agriculture and disaster management, are
relying on accurate geocentric datum. Therefore, if the national geocentric datum
is not accurate and updated, it will lead to misinterpretation and wrong decision
making on land, property and other related matters. For instance, there could be a
risk in the cadastral matters that involve dispute in the boundaries, size and shape
of land parcels due to land displacement. Furthermore, any coordinate disparity
between the ''true'' and existing geocentric datum will lead to confusion and
misinterpretation of the actual position, especially when compared to absolute
positioning, e.g. Precise Point Positioning (PPP), results with the existing base
map. On the contrary, when using maps in the same reference system with the
data, the mismatch can be avoided. However, there are users who do not take
notice of the different reference system used in the data and maps or the existence
of local deformation, but usually attribute such problems to data processing and
positioning technology.
4.3 Decreased Accuracy of Reference Stations Coordinates
The reference stations should be maintained in the order of mm-level accuracy in
terms of correspondence with the latest realization of ITRF. Furthermore, the
reference station should be compatible with the ITRF because it is essential to
avoid transition problems in boundary zones of countries (Pinto
2009
). Inaccurate
coordinates of the reference stations may also limit scientific research and appli-
cations that normally require a reliable coordinate system at the reference stations.
