PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
November 2016
845
U
pdate
Everything has changed with reference to the coordinate sys-
tems of Mauritius since 1999:
“The Ministry of Housing and Lands (MHL) iden-
tified the need to develop a new geodetic datum to
support and maintain the Digital Cadastral Database
(DCDB) in line with Government initiatives to mod-
ernize land administration in Mauritius.
In 2008, Landgate (Australia) undertook a rigorous
assessment of all available geodetic survey data com-
prising the 1934 triangulation survey, and GPS surveys
conducted in 1994 and 2001. This analysis revealed that
these surveys, either in combination or singularly, were
not of sufficient accuracy for the basis of a new geodet-
ic datum. In addition, new GPS observations were re-
quired to accurately position the Island of Mauritius in
a global sense. Landgate recommended a new GPS sur-
vey, with stringent survey practices, to deliver the re-
quired accuracy. This survey was conducted by MHL in
July 2008 and Landgate processed the data with assis-
tance from Geoscience Australia (GA) and determined
the new datum through rigorous network adjustment.
The new Geodetic Datum for Mauritius is named Geo-
centric Datum of Mauritius 2008 (GDM2008) and deriva-
tive mapping coordinates based on Universal Transverse
Mercator (UTM) is named Map Grid of Mauritius 2008
(MGM2008). The datum is based on the World Geodetic
System 1984 (WGS84) reference ellipsoid. The reference
coordinates in International Terrestrial Reference Frame
(ITRF) 2005@2020 were derived for two datum points
namely Grand Bassin and The Mount and the GPS sur-
veys were adjusted on these two datum points by least
square
(sic – Ed.)
adjustments.
Based on the above adjusted primary control points, the
Geodetic Project Team of the Cadastre Unit designed, ob-
served and processed a secondary GPS network consisting
of 61 control points spread over the whole island. This net-
work included 17 primary control points which were held
fixed during adjustment and the resulting average error
ellipse of the adjusted points for both the semi major and
semi minor axes are 6mm. The whole exercise was carried
out between 2010 and 2012.
To cater for plane surveys, a plane coordinate system
has been devised that minimizes the effect of projection
scale factor. It is based on GDM2008 datum and Lambert
Conformal Conic Two Parallel map projection and is re-
ferred to as the Local Grid Mauritius 2012 (LGM2012)”
(MHL-2013).
The contents of this column reflect the views of the author, who is
responsible for the facts and accuracy of the data presented herein.
The contents do not necessarily reflect the official views or policies of
the American Society for Photogrammetry and Remote Sensing and/
or the Louisiana State University Center for GeoInformatics (C
4
G).
This column was previously published in
PE&RS
.
ASPRS
Certification
Program
ASPRS certification is official
recognition by one’s colleagues and
peers that an individual has demon-
strated professional integrity and
competence in his or her field.
Apply for certification as a
• Photogrammetrist
• Mapping Scientist – Remote
Sensing
• Mapping Scientist – GIS/LIS
• Photogrammetric Technologist
• GIS/LIS Technologist
• Remote Sensing Technologist
• Certified Mapping Scientist – Lidar
• Certified Lidar technologist
THE
IMAGING & GEOSPATIAL
INFORMATION SOCIETY
/
Certification-Program.html
