Convert HK1980GRID coordinates to HK80GEO coordinates

HK1980GRID_TO_HK80GEO(N, E)

Arguments

N	Numeric, Northern coordinate in meters
E	Numeric, Eastern coordinate in meters

Details

This function uses equation 3, 4, 5 to convert the HK1980GRID coordinates into HK80GEO coordinates. More details could be found on the explanatory notes Page C9.

Value

latitude

latitude in decimal degrees

longitude

longitude in decimal degrees

References

Survey & Mapping Office Lands Department, Hong Kong Government (1995). Explanatory Notes on Geodetic Datums in Hong Kong, available at: http://www.geodetic.gov.hk/smo/gsi/data/pdf/explanatorynotes.pdf

Author

Jinlong Zhang

Note

The coordinates should be within the range of Hong Kong. Providing coordinates outside Hong Kong will lead to wrong results.

Examples

options(digits = 15)
HK1980GRID_TO_HK80GEO(820351.389, 832591.320)
#>           latitude        longitude
#> 1 22.3237017196981 114.138734989417

### $latitude
### [1] 22.3237017196981
### 
### $longitude
### [1] 114.138734989417

#### The answer from the online conversion tool
### 22.323701767
### 114.138734989