m.transform.1grass man page

m.transform — Computes a coordinate transformation based on the control points.


miscellaneous, transformation, GCP


m.transform --help
m.transform [-srx] group=name order=integer [format=string[,string,...]] [input=name] [--help] [--verbose] [--quiet] [--ui]


Display summary information
Reverse transform of coords file or coeff. dump
Target east,north coordinates to local x,y
Display transform matrix coefficients
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


group=name [required]
Name of input imagery group
order=integer [required]
Rectification polynomial order
Options: 1-3
Output format
Options: idx, src, dst, fwd, rev, fxy, rxy, fd, rd
Default: fd,rd
idx: point index
src: source coordinates
dst: destination coordinates
fwd: forward coordinates (destination)
rev: reverse coordinates (source)
fxy: forward coordinates difference (destination)
rxy: reverse coordinates difference (source)
fd: forward error (destination)
rd: reverse error (source)
File containing coordinates to transform ("-" to read from stdin)
Local x,y coordinates to target east,north


m.transform is an utility to compute transformation based upon GCPs and output error measurements.


For coordinates given with the input file option or fed from stdin, the input format is "x y" with one coordinate pair per line.

The transformations are:


e = [E0 E1][1].[1]
    [E2  0][e] [n]
n = [N0 N1][1].[1]
    [N2  0][e] [n]


e = [E0 E1 E3][1 ] [1 ]
    [E2 E4  0][e ].[n ]
    [E5  0  0][e²] [n²]
n = [N0 N1 N3][1 ] [1 ]
    [N2 N4  0][e ].[n ]
    [N5  0  0][e²] [n²]


e = [E0 E1 E3 E6][1 ] [1 ]
    [E2 E4 E7  0][e ].[n ]
    [E5 E8  0  0][e²] [n²]
    [E9  0  0  0][e³] [n³]
n = [N0 N1 N3 N6][1 ] [1 ]
    [N2 N4 N7  0][e ].[n ]
    [N5 N8  0  0][e²] [n²]
    [N9  0  0  0][e³] [n³]

["." = dot-product, (AE).N = N’EA.]

In other words, order=1 and order=2 are equivalent to order=3 with the higher coefficients equal to zero.

See Also

i.rectify, v.rectify, v.transform


Brian J. Buckley
Glynn Clements
Hamish Bowman

Last changed: $Date: 2014-11-28 16:46:08 +0100 (Fri, 28 Nov 2014) $

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