Articles in the Articles Category
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.
Conventionally, the potential difference between two points P and Q located on the Earth’s surface are determined by gravimetry and levelling (Heiskanen and Moritz 1967), the drawback of which is that it is almost impossible to connect these two points in the case that they are located on two continents, because it is well known that the potential surface of the mean sea level (MSL) is not an equipotential surface. In another aspect, if given the gravity data on the Earth’s surface, one might determine the potential difference between two points by using the Stokes method or Molodensky method (ibid). In this case the potential field is determined and consequently the potential difference between two arbitrary points could be determined.
26th ACRS 2005, 7-11, November, 2005 Hanoi, Vietnam
The 26th Asian Conference on Remote Sensing (ACRS) and 2nd …
says Prof. YQ Chen, Department of Land Surveying and …
NSDI in India: A dream being pursued
National Spatial Data Infrastructure (NSDI) …
The Indian ionosphere is characterized by large horizontal gradients, intense irregularities, large dayto- day variations and equatorial anomaly conditions, there is clear necessity to thoroughly understand the ionospheric time delay effects on the GPS signals. The ionospheric delay error is a function of Total electron content (TEC) which is one of the dominant errors.
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(5.00 out of 5)