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DATABASE |
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The electronic databank of a relief of a surface of the ground is submitted by base of figures of a relief of all surface of the ground and a control system of a database. The base of figures of a relief of a surface of the ground is executed as the digital problem-oriented model of the district containing the information:
- About a relief of a surface of all planet the Earth;
- About artificial obstacles, their scheduled position and relative heights;
- Matrix of amendments of transition from heights is relative quasi to heights is relative elipse WGS-84.
The base of figures of a relief of a surface of the ground corresponds to the following basic requirements:
- In a database are taken into account:
а) Absolute heights of objects of a lay of land:
Horizontals;
Marks of heights;
Items GGN (geographical geodetic network);
Lakes with designated reductions;
Large water basins with designated reductions;
Water areas of the seas and oceans;
б) Relative heights of artificial obstacles:
Cities;
Settlements;
Television and radiomasts, towers;
Capital constructions of tower type outside of settlements;
Woods high;
Transmission lines.
- The data are submitted in system of coordinates WGS-84,
- Readout of heights is carried out concerning an average level the seas (MSL),
- Average-quadratic an error of definition of a site of objects of a lay of land and artificial obstacles on initial materials in the plan - no more than 50 m,
- The limiting values of the errors equal or big trebled and double value average-quadratic to an error, are supposed with probabilities 5% and 10%,
- accordingly, limiting mistake of representation of value of altitude in a vertical plane of objects of a lay of land and artificial obstacles - no more values plus of 30 m and a minus of 0 m with probability 5%,
- All surface of the ground is divided into cells, which linear sizes of no more linear sizes of a cell in area of equator with the angular sizes 15х15 angular seconds,
- The angular sizes of cells for various latitudes of district are resulted in tab. 1.
| Table 1 |
| Resolution of a database of a relief of a surface of the ground |
| Latitude |
Step of a cell, ang. sec. |
| on Longitude |
on Latitude |
| 88° - 90° |
450 |
15 |
| 84° - 88° |
120 |
15 |
| 80° - 84° |
60 |
15 |
| 56° - 80° |
30 |
15 |
| 0° - 56° |
15 |
15 |
| * The increase in the size of cells which covers a water table of the globe is supposed. |
- To each cell values of altitude of the best point from structure of absolute altitude of objects of a lay of land and relative altitude of the artificial obstacles which are taking place within the limits of district which is covered with a cell are appropriated.
The note. If the object dominating over altitude settles down near to border of a cell on distance of no more double value verage-quadratic errors in the plan it is taken into account at definition of altitude of the next cell
- Step-type behaviour of representation of altitude of cells - no more 30 m.
- The level of assurance of quality of data processing is estimated by probability of the undetected destruction which is equal or no more than 10-5 that corresponds " to the Level 2 ".
- At creation of base the opportunity of an establishment of a chain of passage of the data of a lay of land and artificial obstacles is stipulated from the end user up to the supplier.
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