m.transform(1grass)

Usage

m.transform

m.transform --help

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

Keywords

miscellaneous, transformation, GCP

Overview

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

If coordinates are given with the input file option or fed from stdin, both the input and the output format is "x y" with one coordinate pair per line. Reverse transform is performed with the -r flag.

The format option determines how control points are printed out. A summary on the control points can be printed with the -s flag. The summary includes maximum deviation observed when transforming GCPs and overall RMS. The format option is ignored when coordinates are given with the input file option.

Notes

The transformations are:

order=1:

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

order=2:

    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]

order=3:

    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.

Source code

Available at: m.transform source code (history)

Accessed: Monday Feb 24 17:51:29 2025

Releases

5 releases since Debian 9 (Stretch); the text changed 4 times.

9
10
11
12
13