DESCRIPTION

v.transform transforms a vector map layer from one coordinate system into another coordinate system.

NOTES

When using an ASCII table containing source and target coordinate pairs, in each row four coordinate values separated by white space have to be specified. Comments are permitted and have to be indicated by a '#' character.

Example for a points file of a linear transformation from XY to UTM coordinates (L: left, R: right, U: upper, L: lower, N, S, W, E): 

    # Linear transformation from XY to UTM coordinates:
    # 4 maps corners defined
    # UL NW
    # UR NE
    # LR SW
    # LL SE
    -584 585  598000 4920770
    580  585  598020 4920770
    580  -600 598020 4920750
    -584 -600 598000 4920750
The ground control points may be also (ir)regularly distributed and can be more than four points.

EXAMPLE

Most DXF/DWG drawings are done within XY coordinates. To transform them to a national grid, we can use 'v.transform' with a 4 point transformation
v.transform -t in=watertowerXY out=watertowerUTM points= wt.points zscale=0.04 zshift=1320

SEE ALSO

GRASS 5.7 tutorial pages

AUTHOR

Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date$