Allerton J.,University of New South Wales |
Janssen V.,Land and Property Information |
Kearsley A.H.W.,University of New South Wales
CEUR Workshop Proceedings | Year: 2015
AUSGeoid09 is the latest model used to convert Global Navigation Satellite System (GNSS) derived ellipsoidal heights to heights in the Australian Height Datum (AHD). While previous studies have evaluated the performance of the AUSGeoid09 model across Australia, such studies have not focused on mountainous regions in particular. This paper evaluates AUSGeoid09 in the Blue Mountains region of New South Wales from a practical user's point of view. Along a 90 km stretch of road incorporating flat to mountainous terrain, comparisons were undertaken between AUSGeoid09-derived heights and published AHD heights, using repeated Network Real Time Kinematic (NRTK) GNSS observations. The performance of AUSGeoid09 was also evaluated relative to its predecessor, AUSGeoid98, and the latest gravimetric model AGQG2009. It was found that AUSGeoid09 performs well across the study area and provides a significant improvement over AUSGeoid98. AUSGeoid09 generally allows AHD height determination at the ±0.03 m level (1 sigma) in flat terrain and at the ±0.06 m level (1 sigma) in mountainous terrain. However, across the entire study area, AUSGeoid09-derived AHD heights are consistently lower than the published AHD heights. Comparison of the results obtained with AUSGeoid09 against those using AGQG2009 in flat terrain illustrates the benefit that the introduction of the geometric component of AUSGeoid09 has had on the determination of AHD heights with satellite technology. However, for elevations above 500 m it appears that the geometric component degrades the fit to AHD in the study area, indicating that there is room for improvement in regards to future versions of the AUSGeoid model. Copyright © by the paper's authors.
Taylor D.,Land and Property Information
Survey Review | Year: 2011
This paper should be of interest to any surveyor or family historian. The history of the broad arrow is one of intrigue and its origin is relatively unknown to many people. Its origin can be traced back to 1330 when it was used to establish ownership as the King's property. The King Edward III marked each item with an arrow from his own coat of arms.The use of the broad arrow as a government mark was not limited to England. It was also used to mark trees owned by the King in the colony of America and they initiated the position of "Surveyor-General of His Majesty's Woods". The first use of the broad arrow in the colony of New South Wales had nothing to do with surveying. It marked the uniforms of the King's property -the uniforms of the convicts. It would also be used to mark government buildings of note. It would not be until an Act of Parliament (Act 16 Vic. No. 15), enacted 1852, that established the broad arrow for exclusive use of the Government and a year later, the Instruction for marking Crown Land by Government Surveyors was issued. Since that date, the broad arrow found its destiny as a survey mark and good examples can be still found across the state. © 2011 Survey Review Ltd.
Janssen V.,Land and Property Information |
Haaudyk J.,Land and Property Information |
McElroy S.,Land and Property Information |
Kinlyside D.,Land and Property Information
International Journal of Geoinformatics | Year: 2011
Global Navigation Satellite System (GNSS) Continuously Operating Reference Station (CORS) networks are being introduced across many countries to provide improved access to positioning infrastructure for a wide range of applications and a solid platform for research and innovation involving satellite positioning technology. This paper discusses the challenges involved in establishing a CORS network, using the experiences from CORSnet-NSW as an example. The purpose of a CORS network determines the required network density and station monumentation. The logistics involved in physically building the monument and installing the electronic equipment are some of the easiest issues requiring consideration. Collaboration with other organisations hosting a CORS, long-term tenure of the land and/or building to be used, site access, system redundancy and communications all play crucial roles. In addition, several operational aspects need to be addressed in order to provide (and achieve) reliable GNSS positioning of homogeneous and high accuracy across the network These include the consistent connection to a high-quality datum, GNSS-based height transfer considerations, the me of absolute GNSS antenna models, stability and integrity monitoring, and the possible contribution to regional or global geodesy initiatives. © Geoinformatics International.