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. |