The Second Precise Levelling Network of Peninsular Malaysia

Ses, Sahrum; Mohamed, Azhari

doi:10.1179/003962609x451627

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…A levelling-only vertical datum is defined here as a national levelling network constrained at one or more tide-gauges, with the zero reference defined by local MSL only or local MSL that has been corrected by a SSTop model to yield a better estimate of the quasi/geoid. The most common type of national vertical datum is where the levelling network is fixed to MSL at one tide-gauge in a national adjustment (e.g., Vaníček 1991;Zilkoski et al 1992;Christie 1994;Ihde et al 2002;Yang et al 2003;Ses and Mohamed 2009;Abeyratne et al 2010). The AHD and CGVD28 are possibly the only current large national vertical datums where the levelling network is fixed (with the exception of one tide-gauge in the CGVD) (Lachapelle and Gareau 1980) to MSL at multiple tide-gauges.…”

Section: Option 1: a Levelling-only New Avdmentioning

confidence: 99%

“…Fixing a levelling-only vertical datum to MSL (with or without SSTop corrections) at one tide-gauge could be effective with a high quality levelling network of limited extent e.g., Taiwan (Yang et al 2003) or Malaysia (Ses and Mohamed 2009). However, for large levelling networks covering entire continents such as Australia, systematic levelling errors accumulating over long distances and/or gross errors in poorly-checked sections degrade the resulting heights (e.g., Morgan 1992;Filmer and Featherstone 2009).…”

Section: Journal Of Spatial Science [Submitted]mentioning

confidence: 99%

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Three viable options for a new Australian vertical datum

Filmer

Featherstone

2012

Journal of Spatial Science

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While the Intergovernmental Committee on Surveying and Mapping (ICSM) has stated that the Australian Height Datum (AHD) will remain Australia's official vertical datum for the short to medium term, the AHD contains deficiencies that make it unsuitable in the longer term. We present and discuss three different options for defining a new Australian vertical datum (AVD), with a view to encouraging discussion into the development of a medium-to long-term replacement for the AHD. These options are a i) levelling-only, ii) combined, and iii) geoid-only vertical datum. All have advantages and disadvantages, but are dependent on availability of and improvements to the different data sets required. A levelling-only vertical datum is the traditional method, although we recommend the use of a sea surface topography (SSTop) model to allow the vertical datum to be constrained at multiple tide-gauges as an improvement over the AHD. This concept is extended in a combined vertical datum, where heights derived from GNSS ellipsoidal heights and a gravimetric quasi/geoid model (GNSS-geoid) at discrete points are also used to constrain the vertical datum over the continent, in addition to mean sea level and SSTop constraints at tide-gauges. However, both options are ultimately restricted by the requirement to upgrade the Australian National Levelling Network (ANLN). It is also desirable that the ANLN be kept in reasonable shape for the validation or testing of height products. On the other hand, a geoid-only vertical datum, where GNSS-geoid is used to continuously define the vertical datum, has advantages primarily because it avoids the requirement to level long distances to upgrade the levelling network. However, it is not routinely possible to realise a geoid of the desired 1-2 cm accuracy necessary to develop a geoid-only vertical datum, especially to a local precision that can match levelling, such that a geoid-only vertical datum is considered a longterm proposition. In the meantime, a combined vertical datum is a more suitable option for any new AVD in the next decade or so, although a geoid-based vertical datum which retains only the higher quality parts of the ANLN in Australia's densely settled areas, but connected by a geoid model rather than continent-wide levelling, may also have merit.

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Section: Option 1: a Levelling-only New Avdmentioning

confidence: 99%

Section: Journal Of Spatial Science [Submitted]mentioning

confidence: 99%

Three viable options for a new Australian vertical datum

Filmer

Featherstone

2012

Journal of Spatial Science

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Mobile precise trigonometric levelling system based on land vehicle: an alternative method for precise levelling

Zou

Zhu

et al. 2016

Survey Review

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Unification of Vertical Datum In Sabah and Sarawak

et al. 2014

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The present vertical datums in Sabah and Sarawak (East Malaysia) are based upon various tide gauge measurements of mean sea level over certain period defined locally, are manifested by a physical framework of vertical reference point i.e benchmarks. An effort to establish a unified vertical network in Sabah and Sarawak has undergone very tedious survey operation, lack of access routes to connect levelling network due to geographical setting constraint, and it is too costly to be fully implemented. This paper discussed the current status of vertical datum in East Malaysia as well as the concept of realizing new vertical datum based on gravimetric geoid model.

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The Second Precise Levelling Network of Peninsular Malaysia

Cited by 4 publications

References 2 publications

Three viable options for a new Australian vertical datum

Three viable options for a new Australian vertical datum

Mobile precise trigonometric levelling system based on land vehicle: an alternative method for precise levelling

Unification of Vertical Datum In Sabah and Sarawak

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