HotineObliqueMercatorProjection.RectifiedGridAngle Property
Gets the grid azimuth of the central line.
Syntax
public System.Double RectifiedGridAngle { get; }Property Value
Default: Must be specified in constructor.
An azimuth (direction) in degrees, clockwise from grid north.
Remarks
This angle becomes the grid azimuth of the central line, and is implemented by a final rotation of the projected plane. In EPSG, this parameter is called Angle from Rectified to Skew Grid. In PROJ (since version 4.8) and in libproj4, it is galled gamma.
The common practice, except in Malaysia and Denmark, is that this angle equals the Azimuth, which means that grid north will equal true north at the projection center.
In Malaysia, this angle differs slightly from the Azimuth in a way that makes grid north equal to true north at the natural origin near the equator instead (see TrueOrigin), in agreement with the original definition of the Hotine projection for Malaysia.
Denmark does not use Hotine officially, but the projection can approximate the old System 34, which can be useful since the official formulas are unusual. In the two projection zones for System 34, the approximation uses two central lines with azimuths near north but arranged to make the lines parallel in Denmark, and the RectifiedGridAngle is zero. It seems the Danes wanted the two projected grids to be nearly axis-parallel with each other and also with an older single-zone projection.
Platforms
Windows, Linux, Android