uk.me.jstott.jcoord
Class OSRef

java.lang.Object
  uk.me.jstott.jcoord.CoordinateSystem
      uk.me.jstott.jcoord.OSRef

public class OSRef
extends CoordinateSystem

This class is part of the Jcoord package. Visit the Jcoord website for more information.

Class to represent an Ordnance Survey of Great Britain (OSGB) grid reference.

British National Grid

• Projection: Transverse Mercator
• Reference ellipsoid: Airy 1830
• Units: metres
• Origin: 49°N, 2°W
• False co-ordinates of origin: 400000m east, -100000m north

A full reference includes a two-character code identifying a particular 100,000m grid square. The table below shows how the two-character 100,000m grid squares are identified. The bottom left corner is at the false origin of the grid. Squares without values fall outside the boundaries of the British National Grid.

km	0	100	200	300	400	500	600	700
1200	HL	HM	HN	HO	HP	JL	JM
1100	HQ	HR	HS	HT	HU	JQ	JR
1000	HV	HW	HX	HY	HZ	JV	JW
900	NA	NB	NC	ND	NE	OA	OB
800	NF	NG	NH	NJ	NK	OF	OG	OH
700	NL	NM	NN	NO	NP	OL	OM	ON
600	NQ	NR	NS	NT	NU	OQ	OR	OS
500		NW	NX	NY	NZ	OV	OW	OX
400		SB	SC	SD	SE	TA	TB	TC
300		SG	SH	SJ	SK	TF	TG	TH
200		SM	SN	SO	SP	TL	TM	TN
100	SQ	SR	SS	ST	SU	TQ	TR	TS
0	SV	SW	SX	SY	SZ	TV	TW

Within each 100,000m square, the grid is further subdivided into 1000m squares. These 1km squares are shown on Ordnance Survey 1:25000 and 1:50000 mapping as the main grid. To reference a 1km square, give the easting and then the northing, e.g. TR2266. In this example, TR represents the 100,000m square, 22 represents the easting (in km) and 66 represents the northing (in km). This is commonly called a four-figure grid reference.

It is possible to extend the four-figure grid reference for more accuracy. For example, a six-figure grid reference would be accurate to 100m and an eight-figure grid reference would be accurate to 10m.

When providing local references, the 2 characters representing the 100,000m square are often omitted.

(c) 2006 Jonathan Stott

Created on 11-02-2006

Since:

1.0

Version:

1.0

Author:

Jonathan Stott

Constructor Summary

OSRef(double easting, double northing)
Create a new Ordnance Survey grid reference using a given easting and northing.

OSRef(LatLng ll)
Convert this latitude and longitude into an OSGB (Ordnance Survey of Great Britain) grid reference.

OSRef(java.lang.String ref)
Take a string formatted as a six-figure OS grid reference (e.g.

Method Summary

double	getEasting() Get the easting in metres relative the origin of the British National Grid.
double	getNorthing() Get the northing in metres relative to the origin of the British National Grid.
void	setEasting(double easting) Set the easting for this OSRef.
void	setNorthing(double northing) Set the northing for this OSRef
LatLng	toLatLng() Convert this OSGB grid reference to a latitude/longitude pair using the OSGB36 datum.
java.lang.String	toSixFigureString() Return a String representation of this OSGB grid reference using the six-figure notation in the form XY123456
java.lang.String	toString() Return a String representation of this OSGB grid reference showing the easting and northing.

Methods inherited from class uk.me.jstott.jcoord.CoordinateSystem

getDatum, setDatum

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

OSRef

public OSRef(double easting,
             double northing)
      throws java.lang.IllegalArgumentException

Create a new Ordnance Survey grid reference using a given easting and northing. The easting and northing must be in metres and must be relative to the origin of the British National Grid.

Parameters:

easting - the easting in metres. Must be greater than or equal to 0.0 and less than 800000.0.

northing - the northing in metres. Must be greater than or equal to 0.0 and less than 1400000.0.

Throws:

java.lang.IllegalArgumentException - if either the easting or the northing are invalid.

Since:

1.0

OSRef

public OSRef(java.lang.String ref)
      throws java.lang.IllegalArgumentException

Take a string formatted as a six-figure OS grid reference (e.g. "TG514131") and create a new OSRef object that represents that grid reference. The first character must be H, N, S, O or T. The second character can be any uppercase character from A through Z excluding I.

Parameters:

ref - a String representing a six-figure Ordnance Survey grid reference in the form XY123456

Throws:

java.lang.IllegalArgumentException - if ref is not of the form XY123456

Since:

1.0

OSRef

public OSRef(LatLng ll)

Convert this latitude and longitude into an OSGB (Ordnance Survey of Great Britain) grid reference.

Since:

1.1

Method Detail

toString

public java.lang.String toString()

Return a String representation of this OSGB grid reference showing the easting and northing.

Overrides:

toString in class java.lang.Object

Returns:

a String represenation of this OSGB grid reference

Since:

1.0

toSixFigureString

public java.lang.String toSixFigureString()

Return a String representation of this OSGB grid reference using the six-figure notation in the form XY123456

Returns:

a String representing this OSGB grid reference in six-figure notation

Since:

1.0

toLatLng

public LatLng toLatLng()

Convert this OSGB grid reference to a latitude/longitude pair using the OSGB36 datum. Note that, the LatLng object may need to be converted to the WGS84 datum depending on the application.

Specified by:

toLatLng in class CoordinateSystem

Returns:

a LatLng object representing this OSGB grid reference using the OSGB36 datum

Since:

1.0

getEasting

public double getEasting()

Get the easting in metres relative the origin of the British National Grid.

Returns:

the easting in metres.

Since:

1.0

getNorthing

public double getNorthing()

Get the northing in metres relative to the origin of the British National Grid.

Returns:

the northing in metres.

Since:

1.0

setEasting

public void setEasting(double easting)
                throws java.lang.IllegalArgumentException

Set the easting for this OSRef.

Parameters:

easting - the easting in metres. Must be greater than or equal to 0.0 and less than 800000.0.

Throws:

java.lang.IllegalArgumentException - if the easting is invalid.

setNorthing

public void setNorthing(double northing)
                 throws java.lang.IllegalArgumentException

Set the northing for this OSRef

Parameters:

northing - the northing in metres. Must be greater than or equal to 0.0 and less than 1400000.0.

Throws:

java.lang.IllegalArgumentException - if either the northing is invalid.