A system of vertical control is realised with the establishment of a levelling network whereby the height value of points may be defined. In early 1977, the Department of Survey and Mapping Malaysia (JUPEM) began to undertake definitive steps to prepare for a new vertical control network to replace the old one that had numerous inadequacies. The field operation commenced in 1985 and the Precise Levelling Network (PLN) was completed in 1999. Nowadays, the widespread use of global navigation satellite system (GNSS), give a great impact to height determination. By improving the geoid in the area, a modern height  measurement technique called GNSS heighting can be contemplated as an alternative for  practical height applications. This paper investigates the achievable accuracy of GNSS heighting by comparing GNSS derived orthometric heights with spirit levelled heights of bench marks. It demonstrates GNSS as a viable technique of transforming GNSS ellipsoidal heights to orthometric heights using a local geoid model. Preliminary results indicate that the accuracy achievable by GNSS heighting in Malaysia can provide second order levelling standard. Read More

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