Accuracy of Administrative Maps at Different Levels

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

To be specific, according to the provisions of Article 6 Circular 47/2014/TT-BTNMT the accuracy of administrative maps at different levels is as follows:

- Length error of the map frame edge ≤ 0.2 mm; map diagonal ≤ 0.3 mm; distance between coordinate points and the corners of the map frame ≤ 0.2 mm compared to the theoretical value.

- Limit error in horizontal position:

- Horizontal position error of state coordinate points ≤ 0.3 mm according to the map scale;- Horizontal position error of geospatial objects on the map compared to state coordinate points: For plains: ≤ 1.0 mm; for mountainous and midland regions: ≤ 1.5 mm.

- In cases where symbols on the map are adjacent to each other, it is permissible to shift the objects with lower accuracy to ensure spacing between the objects ≤ 0.3 mm.

- Height error due to the generalization of contour lines ≤ 1/2 of the contour interval. In high mountainous regions with difficult access, the error can be extended to 1 contour interval.

- Height and depth annotations should be rounded to the nearest unit meter.

Administrative maps at all levels are calculated based on the following mathematical premises:

- The national administrative map uses the conformal conic projection with parameters: 2 standard parallels at 11° North latitude, 21° North latitude; central meridian at 108° East longitude; base parallel at 4° North latitude.

- Provincial and district-level administrative maps apply the VN-2000 national reference and coordinate systems: Global ellipsoid WGS-84; semi-major axis of 6378137.0m; flattening ratio of 1:298.257223563; using conformal transverse cylindrical projection with a 6° projection zone and a scale factor k0 = 0.9996; central meridian of each province and centrally-run city as specified in Appendix 4 attached to Circular 47/2014/TT-BTNMT; Vietnam National Height System.

The atlas of administrative maps containing certain types of administrative maps should adhere to the corresponding mathematical premises specified in Clauses 1 and 2, Article 5 of Circular 47/2014/TT-BTNMT.

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

Thuy Tram

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