What is the accuracy of administrative maps of all levels in Vietnam?

What is the accuracy of administrative maps of all levels in Vietnam? (Illustrative photo)

According to the provisions of Article 6 Circular 47/2014/TT-BTNMT, the accuracy of administrative maps of all levels in Vietnam is specified as follows:

- Deviation of edge length ≤ 0,2 mm; diagonals ≤ 0,3 mm; distance between coordinate and corner of the map ≤ 0,2 mm relative to the theoretical value.

- Deviation of real life locations

+ Deviation of locations of government coordinates ≤ 0,3 mm depending on scale;

+ Deviation of geographical features on the map relative to government coordinates: For plateau: ≤ 1,0 mm; for mountainous regions and highlands: ≤ 1,5 mm.

- Where map symbols are positioned close together, for presentation purposes, it is permissible to move symbols indicating features of a lower accuracy so that spacing between symbols ≤ 0,3 mm.

- Deviation in elevation due to displacement of contour lines during generation ≤ 1/2 contour interval. In case of mountainous regions where traverse is difficult, deviation is 1 contour interval.

- Elevation and depth reading is rounded to the nearest meter.

The mathematical basis of administrative maps of all levels in Vietnam is specified as follows:

- Nationwide administrative maps use conical projection grid with the following parameters: 2 standard parallels are 11o North latitude, 21o North latitude; prime meridian of 108o East longitude; base latitude of 4o North latitude.

- Provincial and district administrative maps use the VN-2000 Frame of reference and National coordinate system: Global Ellipsoid WGS-84; semi-major axis of 6378137,0m; flattening of 1:298,257223563; transverse cylindrical grid of the same angle as 6-degree-wide wedge with scale factor k0 = 0,9996; prime meridian of each province and central-affiliated city is specified under Appendix 4 attached hereto; and Vietnam national elevation system.

- Mathematical bases under Clause 1 and Clause 2 of this Article apply to the corresponding types of administrative maps in administrative atlases.

More details can be found in Circular 47/2014/TT-BTNMT effective from August 22, 2014.

Thuy Tram

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