.TH m.transform 1grass "" "GRASS 8.3.1" "GRASS GIS User's Manual"
.SH NAME
\fI\fBm.transform\fR\fR  \- Computes a coordinate transformation based on the control points.
.SH KEYWORDS
miscellaneous, transformation, GCP
.SH SYNOPSIS
\fBm.transform\fR
.br
\fBm.transform \-\-help\fR
.br
\fBm.transform\fR [\-\fBsrx\fR] \fBgroup\fR=\fIname\fR \fBorder\fR=\fIinteger\fR  [\fBformat\fR=\fIstring\fR[,\fIstring\fR,...]]   [\fBinput\fR=\fIname\fR]   [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-s\fR" 4m
.br
Display summary information
.IP "\fB\-r\fR" 4m
.br
Reverse transform of coords file or coeff. dump
.br
Target east,north coordinates to local x,y
.IP "\fB\-x\fR" 4m
.br
Display transform matrix coefficients
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBgroup\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input imagery group
.IP "\fBorder\fR=\fIinteger\fR \fB[required]\fR" 4m
.br
Rectification polynomial order
.br
Options: \fI1\-3\fR
.br
Default: \fI1\fR
.IP "\fBformat\fR=\fIstring[,\fIstring\fR,...]\fR" 4m
.br
Output format
.br
Options: \fIidx, src, dst, fwd, rev, fxy, rxy, fd, rd\fR
.br
Default: \fIfd,rd\fR
.br
\fBidx\fR: point index
.br
\fBsrc\fR: source coordinates
.br
\fBdst\fR: destination coordinates
.br
\fBfwd\fR: forward coordinates (destination)
.br
\fBrev\fR: reverse coordinates (source)
.br
\fBfxy\fR: forward coordinates difference (destination)
.br
\fBrxy\fR: reverse coordinates difference (source)
.br
\fBfd\fR: forward error (destination)
.br
\fBrd\fR: reverse error (source)
.IP "\fBinput\fR=\fIname\fR" 4m
.br
File containing coordinates to transform (\(dq\-\(dq to read from stdin)
.br
Local x,y coordinates to target east,north
.SH DESCRIPTION
\fIm.transform\fR is an utility to compute transformation
based upon GCPs and output error measurements.
.PP
If coordinates are given with the \fBinput\fR file option or fed from
stdin, both the input and the output format is \(dqx y\(dq with one
coordinate pair per line. Reverse transform is performed with the
\fB\-r\fR flag.
.PP
The \fBformat\fR option determines how control points are printed out.
A summary on the control points can be printed with the \fB\-s\fR flag.
The summary includes maximum deviation observed when transforming GCPs
and overall RMS. The \fBformat\fR option is ignored when coordinates
are given with the \fBinput\fR file option.
.SH NOTES
The transformations are:
.PP
order=1:
.br
.nf
\fC
    e = [E0 E1][1].[1]
        [E2  0][e] [n]
    n = [N0 N1][1].[1]
        [N2  0][e] [n]
\fR
.fi
order=2:
.br
.nf
\fC
    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]
\fR
.fi
order=3:
.br
.nf
\fC
    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]
\fR
.fi
[\(dq.\(dq = dot\-product, (AE).N = N\(cqEA.]
.PP
In other words, order=1 and order=2 are equivalent to order=3 with
the higher coefficients equal to zero.
.SH SEE ALSO
\fI
i.rectify,
v.rectify,
v.transform
\fR
.SH AUTHORS
Brian J. Buckley
.br
Glynn Clements
.br
Hamish Bowman
.SH SOURCE CODE
.PP
Available at:
m.transform source code
(history)
.PP
Accessed: Sunday Dec 17 17:22:34 2023
.PP
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.PP
© 2003\-2023
GRASS Development Team,
GRASS GIS 8.3.1 Reference Manual