FME Form: 2024.1

TMAF: Transverse Mercator (Gauss/Kruger) with Affine Post Process

This variation of the Transverse Mercator projection adds an Affine Transformation Post Processor to the normal Transverse Mercator (Gauss/Kruger) algorithm. This variation was specifically added for the National Survey of Sweden.

The Affine Transformation requires six parameters, and these are carried in coordinate system definitions as PARM2 through PARM7. The post processor uses an affine transformation defined as follows:

Xnew = A0 + A1 * Xold + A2 * Yold

Ynew = B0 + B1 * Xold + B2 * Yold

Note that in order for the inverse to function properly, the following condition is not allowed:

A1 * B2 == A2 * B1

Also note that by setting B2 equal to A1, and B1 equal to the complement of A2, one can obtain the Helmert or Similarity Transformation.

Parameter Name

Description

PARM1

Longitude, in degrees, on the central meridian.

PARM2

A0 in Affine Transformation

PARM3

B0 in Affine Transformation

PARM4

A1 in Affine Transformation

PARM5

A2 in Affine Transformation

PARM6

B1 in Affine Transformation

PARM7

B2 in Affine Transformation

ORG_LAT

Latitude, in degrees, of the origin of the projection

SCL_RED

The scale reduction to be applied. This is also known as the scale of the central meridian.

X_OFF

The false easting to be applied to all X coordinates, selected to cause all X coordinates within the coordinate system to be positive values of reasonable size.

Y_OFF

The false northing to be applied to all Y coordinates.