Geoscience Reference
In-Depth Information
4.4 Managing the Geospatial Database
It is realised that significant earth deformation has occurred with evidences as
shown in
Sect. 3
. The static datum option is not appropriate because it would not
effectively consider the significant land displacements. Therefore, one of the
options is to regularly update the geocentric datum in order to update the cadastral
and mapping database. However, this option raises significant issues especially to
a major group of cadastral surveyors and stakeholders due to the assumption of
complexity in managing the updated geospatial database. At this stage, it is
essential to propose the best mechanism to simplify the management of digital
spatial data. With the present computing capability, cartography and Geographical
Information System (GIS) technology, it is possible to transform spatial data from
one epoch and reference frame to the other seamlessly (Pinto
2009
). The important
input
to
allow
this
transformation
is
either
the
velocity
or
transformation
parameters.
5 Concluding Remarks and Future Work
The above review on the status of GDM2000 and several tests about the land
displacements have justified that the existing datum is static and does not
accommodate the land displacements. This implies that the GDM20000 is non-
geocentric, which is only useful for local surveys. In Ranau, for instance, a
significant land displacement up to 17 and 30 cm in north and east components
respectively occurred mainly due to local active faults and the cumulative plate
tectonic motion from 2006 to 2011. The consequences include the following—
inconsistent satellite orbit and coordinate bias, confusion and mismatch with the
base map, decreased accuracy of reference stations coordinates, and problems in
managing cadastral and mapping database.
This study will continue to investigate the variations of land displacement over
a longer period of time. It is essential to understand the tectonic setting and local
land displacement due to either active faults or the influence from nearby earth-
quakes. Thus, the trend of the site velocities can be drawn to formulate the
deformation model for Malaysia. This is an essential step in order to modernize the
existing static datum to a semi-dynamic datum or dynamic datum. These two
options further require the best mechanism to handle spatial data, especially for the
cadastral and mapping applications to meet user requirements over time.
Acknowledgments The authors would like to acknowledge the DSMM for providing the
MyRTKnet data as well as to research funding from UTM Research University Grant (RUG),
Vote 08J75.
