Hotine Oblique Mercator (Deprecated) – Global Mapper

These projections have been deprecated and should not be used. These implementations of the HSO/RSO projection have been replaced by the new Oblique Mercator Azimuth and Oblique Mercator Two Points projection methods. The new projection methods provide the same functionality as these types, but with additional flexibility to support a wider range of Oblique Mercator projections (rectified and un-rectified, natural-origin and center-of-projection based, etc.). This older, deprecated method has been maintained for backward compatibility only; it should not be used for new coordinate system definitions.

The Hotine Oblique Mercator (HOM) projection is a cylindrical, conformal map projection. It is similar to the Mercator projection, except that the cylinder is wrapped around the sphere so that it touches the surface along the great circle path chosen for the central line, instead of along the earth's equator. Scale becomes infinite 90 degrees from the central line and is true along a chosen central line, along two straight lines parallel to the central line, or along a great circle at an oblique angle. The HOM projection is used for geographic regions that are centered along lines that are neither meridians nor parallels, but that may be taken as great circle routes passing through the region, such as the Alaskan panhandle. Two cases of the Hotine Oblique Mercator projection are implemented within the Geographic Calculator, differing only in their defining parameters.

The "Hotine Oblique Mercator (2 Points)" Projection has the following Parameters:

Parameter Name	Parameter String	Units
Latitude of the Origin of the Projection	latitude_of_origin	AngularValue
Latitude of the First Point	standard_parallel1	AngularValue
Longitude of the First Point	standard_longitude1	AngularValue
Latitude of the Second Point	standard_parallel2	AngularValue
Longitude of the Second Point	standard_longitude2	AngularValue
False Easting	false_easting	LinearValue
False Northing	false_northing	LinearValue

The Rectified Skew Orthomorphic (RSO) projection is used throughout the world, particularly in Malaysia. The RSO projection is equivalent to a HOM projection except that the defining parameters are different. You can specify a HOM projection by specifying a point and the azimuth defining the central line. This case allows for the entering of parameters for the RSO projection. (NOTE: there are 2 different implementations of the 1 Point HOM)

The "Hotine Oblique Mercator (1 Point & Azimuth)" Projection has the following Parameters:

Parameter Name	Parameter String	Units
Longitude of the Central Meridian	central_meridian	AngularValue
Latitude of the Origin of the Projection	latitude_of_origin	AngularValue
Azimuth of the Central Line	azimuth	AngularValue
Azimuth Skew of Central Line	azimuth_skew	AngularValue
Scale Reduction Factor at the Center of the Projection	scale_factor	Double
False Easting	false_easting	LinearValue
False Northing	false_northing	LinearValue

Note: The Hotine Oblique Mercator Projections have been deprecated in favor of the Oblique Mercator Azimuth and Oblique Mercator Two Point Projections.