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Oblique Mercator Projection

The Oblique Mercator Projection is used to show regions along a great circle other than the Equator (Mercator) or a meridian (Transverse Mercator). This kind of map can be made to show as a straight line the shortest distance between any two preselected points along the selected great circle.

Some projections that are derived from the Oblique Mercator projection are:

• Hotine Oblique Mercator projection;
• Laborde Oblique Mercator projection;
• Rosenmund (Swiss) Oblique Mercator projection;

Required Parameters

To convert Oblique Mercator coordinates, the following parameters have to be set:

• False Northing;
• False Easting;
• Latitude Of Origin;
• Central Meridian;
• Azimuth;
• Rectified Grid Angle;
• Scale Factor.

Eye4Software GPS Toolkit

The following code sample (VBScript) shows how to use the Oblique Mercator Projection from the Eye4Software GPS Toolkit:

' demo_obliquemercator.vbs
'
' This demo translates lat/lon coordinates (WGS84) to LV95 coordinates (CH1903+) using
' oblique mercator projection
'
' This demo specifies a map grid based on the Oblique Mercator projection, by setting all geodetic parameters. 
'
' If you want to convert using one of the 4000 grids that are included in the component,
' you should have a look at the demo_gridsimple.vbs demo (recommended for users with less or no experience in geodesy).

Option Explicit

Dim objDatumSrc, objDatumDst, objGridSrc, objGridDst, objProjection, objConstants

Set objDatumSrc		= CreateObject ( "Eye4Software.GpsDatumParameters" )
Set objDatumDst		= CreateObject ( "Eye4Software.GpsDatumParameters" )
Set objGridSrc 		= CreateObject ( "Eye4Software.GpsGridParameters" )
Set objGridDst 		= CreateObject ( "Eye4Software.GpsGridParameters" )
Set objProjection   	= CreateObject ( "Eye4Software.GpsProjection" )
Set objConstants 	= CreateObject ( "Eye4Software.GpsConstants" )

WScript.Echo "Eye4Software GPS Toolkit " & objProjection.Version & " - Oblique Mercator Projection Demo" 
WScript.Echo

' // Start of parameters part //

' Set Source Datum: WGS84
objDatumSrc.Axis		= 6378137.000
objDatumSrc.Flattening		= 298.257223563

' Set Source GridL: Latitude/Longitude
objGridSrc.Projection		= 0
objGridSrc.Datum		= objDatumSrc

' Set Destination Datum: WGS84
objDatumDst.Axis		= 6377397.155
objDatumDst.Flattening		= 299.1528128

objDatumDst.TranslationX	= 674.374
objDatumDst.TranslationY	=  15.056
objDatumDst.TranslationZ	= 405.346

' Set destination grid: LV95
objGridDst.Projection		= objConstants.GPS_PROJECTION_OBLIQUEMERCATOR
objGridDst.Datum		= objDatumDst
objGridDst.FalseNorthing	= 1200000
objGridDst.FalseEasting		= 2600000
objGridDst.OriginLatitude	= 46.95240555555556
objGridDst.OriginLongitude	=  7.43958333333333
objGridDst.ScaleFactor		= 1.0

' Set Source coordinates
objProjection.Latitude		= 46.820000
objProjection.Longitude		=  8.230000

' // End of parameters part //

' Perform the transformation
WScript.Echo "Convert from Latitude / Longitude to LV95 ( CH1903+ ) using oblique mercator projection"
WScript.Echo
WScript.Echo "Latitude    = " & objProjection.Latitude
WScript.Echo "Longitude   = " & objProjection.Longitude
WScript.Echo

objProjection.TransformGrid objGridSrc, objGridDst

' Return the result
WScript.Echo "Result: " & objProjection.LastError & " (" & objProjection.LastErrorDescription & ")"
WScript.Echo
If ( objProjection.LastError = 0 ) Then
	WScript.Echo "Northing    = " & objProjection.Northing
	WScript.Echo "Easting     = " & objProjection.Easting
End If

WScript.Echo "Ready."

Click here to show a list of all supported map projections.