Articles in the Articles Category
As the GPS surveying techniques started showing promise of high accuracy geodetic positioning in the early 1990s, few “open-minded” geodesists realized the possibility of using ellipsoidal heights in place of orthometric heights. Many conceptual approaches were mentioned and proposed in various applications. However, Steinberg and Papo were the fi rst to publish a paper entitled “Ellipsoidal Heights: The Future of Vertical Geodetic Control” (GPS World, Vol. 9, No. 2, 1998). As could be expected, Petr Vanicek, a geodesy professor, was quick to downplay the proposed new “type” of vertical control (GPS World, Vol. 9, No. 4, 1998). It seems that Steinberg and Papo did not “defend” their new proposal. Thus, in this paper, a review has been made to check and comment on Vanicek’s example against the ellipsoidal heights, reference to orthometric islands, and issuance of a warning for non-dissemination of ellipsoidal heights to Canadian users.
In early 2004 a plan was hatched to develop a Global Navigation Satellite System (GNSS) receiver based around Field Programmable Gate Array (FPGA) technology as a platform to support research in this fi eld. A joint project was set up between the School of Surveying and Spatial Information Systems (SISS) at the University of New South Wales and the National ICT Australia (NICTA), and soon after a small team was established. The team consisted of Kevin Parkinson, a post-graduate student at SISS with experience in FPGA and circuit board design, Frank Engel, a researcher with NICTA with software, Real Time Operating Systems (RTOS) and VHDL design knowledge and me, Peter Mumford from the SISS GNSS research group. At the end of the project we hoped to have an L1 GPS receiver running on a custom circuit board with the baseband processor and navigation solution processor running on an FPGA chip. The project is coming to an end now, and in this article, I will describe our design path, what has been achieved to date and then some potential research areas, but fi rst a little background.
GNSS is a global navigation satellite system comprising of network of satellites that transmit ranging signals used for positioning and navigation anywhere around the globe; on land, in the air or at sea. The US Global Positioning System (GPS/Navstar GPS), the Russian Global Navigation Satellite System (GLONASS) and the upcoming European GALILEO system, Data communications satellites with navigation payloads and Augmentation systems are all part of GNSS.
What leads us to make a map?
A desire to locate from anything to everything …
January 2006
First Asia-Pacific Conference for ESRI Users January 12-13, …
Kumar Mapping (KMap) System
I recently checked the following two “real” products …
The Great Trigonometrical Survey of India was completed in 19th century under leadership of the great surveyors- Lambton and Sir George Everest. It is inconsistent and inadequate. Accuracy of the network is only of the 1st order or less. First order was defined as better than only 1 in 50,000 only. Reference surface and Datum- The Everest Spheroid was given by Sir George Everest in 1830. Center of Everest Spheroid is about a km away from the center of gravity of the Earth; hence it is non-geocentric. Thus it is inaccurate and unsuitable under present circumstances. Leveling network of India has inconsistencies. Gravity observations were not carried out and not taken in to consideration. It was not appropriately adjusted. Indian Absolute Gravity Datum does not exist. Absolute gravimeters have not yet been used to define Gravity Datum in India. Topographical maps are on Polyconic projection. Assumptions and approximations accepted make it a non-projection. The earth is assumed to be fiat and there are no distortions of any kind. The projection has created problems in digitization, compilation and integration of maps. Design of the Grid adopted in India is not satisfactory. Distortion at central parallel is 1 in 824, which is quite high. There is archaic Restriction policy, which is not transparent and hinders research and development India has to make a choice between chaos and development. These problems have been discussed in detail in this paper. How India should go about to establish new geodetic infrastructure for systematic development and research, has been described in this paper.
(5.00 out of 5)