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

       Brian J. Buckley
       Glynn Clements
       Hamish Bowman

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.

       miscellaneous, transformation, GCP

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

       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.

i.ortho.transform,i.rectify,v.rectify,v.transform

       Available at: m.transform source code (history)

       Accessed: Friday Apr 04 01:20:44 2025

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       © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual

GRASS 8.4.1                                                                                  m.transform(1grass)

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

   Flags:-s
           Display summary information

       -r
           Reverse transform of coords file or coeff. dump
           Target east,north coordinates to local x,y

       -x
           Display transform matrix coefficients

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:group=name[required]
           Name of input imagery group

       order=integer[required]
           Rectification polynomial order
           Options: 1-3
           Default: 1format=string[,string,...]
           Output format
           Options: idx,src,dst,fwd,rev,fxy,rxy,fd,rd
           Default: fd,rdidx: 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)

       input=name
           File containing coordinates to transform ("-" to read from stdin)
           Local x,y coordinates to target east,north