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v.transform(1)		    GRASS GIS User's Manual		v.transform(1)

NAME
       v.transform   - Performs	an affine transformation (shift, scale and ro-
       tate) on	vector map.

KEYWORDS
       vector, transformation, geometry, GCP

SYNOPSIS
       v.transform
       v.transform --help
       v.transform   [-twxyab]	 input=name	[layer=string]	   output=name
       [xshift=float]	  [yshift=float]     [zshift=float]	[xscale=float]
       [yscale=float]	    [zscale=float]	 [zrotation=float]	 [col-
       umns=name[,name,...]]   [--overwrite]  [--help]	[--verbose]  [--quiet]
       [--ui]

   Flags:
       -t
	   Shift all z values to bottom=0

       -w
	   Swap	coordinates x, y and then apply	other parameters

       -x
	   Swap	coordinates x, z and then apply	other parameters

       -y
	   Swap	coordinates y, z and then apply	other parameters

       -a
	   Swap	coordinates after the other transformations

       -b
	   Do not build	topology

       --overwrite
	   Allow output	files to overwrite existing files

       --help
	   Print usage summary

       --verbose
	   Verbose module output

       --quiet
	   Quiet module	output

       --ui
	   Force launching GUI dialog

   Parameters:
       input=nameA [required]
	   Name	of input vector	map
	   Or data source for direct OGR access

       layer=string
	   Layer number	or name	('-1' for all layers)
	   A single vector map can be connected	to multiple  database  tables.
	   This	 number	 determines  which table to use. When used with	direct
	   OGR access this is the layer	name.
	   Default: -1

       output=nameA [required]
	   Name	for output vector map

       xshift=float
	   Shifting value for x	coordinates
	   Default: 0.0

       yshift=float
	   Shifting value for y	coordinates
	   Default: 0.0

       zshift=float
	   Shifting value for z	coordinates
	   Default: 0.0

       xscale=float
	   Scaling factor for x	coordinates
	   Default: 1.0

       yscale=float
	   Scaling factor for y	coordinates
	   Default: 1.0

       zscale=float
	   Scaling factor for z	coordinates
	   Default: 1.0

       zrotation=float
	   Rotation around z axis in degrees (counter-clockwise)
	   Default: 0.0

       columns=name[,name,...]
	   Name	of attribute column(s) used as transformation parameters
	   Format: parameter:column, e.g. xshift:xs,yshift:ys,zrot:zr

DESCRIPTION
       v.transform performs an affine transformation (translate	and rotate) of
       a vector	map. An	affine transform includes one or several linear	trans-
       formations (scaling, rotation) and translation (shifting). Several lin-
       ear  transformations can	be combined in a single	operation. The command
       can be used to georeference unreferenced	vector maps or to  modify  ex-
       isting geocoded maps.

NOTES
       Coordinate transformation based on Ground Control Points	(GCPs) is done
       by v.rectify and	not supported by v.transform.

       Transformation parameters (i.e. xshift, yshift, etc.)  can  be  fetched
       from  attribute	table connected	to the vector map. In this case	vector
       objects can be transformed with different  parameters  based  on	 their
       category	number.	If the parameter cannot	be fetched from	the table, de-
       fault value is used instead.

       Note that the transformation matrix can be printed by m.transform.

EXAMPLE
   DXF/DWG drawings
       Most DXF/DWG drawings are done within XY	coordinate space. To transform
       them to a national grid,	we can use v.transform together	with v.rectify
       and a first-order transformation.
       v.transform -t in=watertowerXY out=watertower_z zscale=0.04 zshift=1320
       v.rectify in=watertower_z out=watertowerUTM points=wt.points order=1

   Extrude 2D vector points to 3D based	on attribute column values
       Spearfish example with manual table editing for vertical	shift:
       # work on own map copy:
       g.copy vect=archsites@PERMANENT,myarchsites
       # add new 'zs' column to	later store height of each site:
       v.db.addcolumn myarchsites col="zs double precision"
       v.db.update myarchsites layer=1 column=zs value="cat * 1000"
       # perform z transformation:
       v.transform -t input=archsites output=myarchsites3d column="zshift:zs" table="archsites_t"
       # drop table containing transformation parameters:
       echo "drop table	archsites_t" | db.execute
       The resulting map is a 3D vector	map.

   Extrude 2D vector points to 3D based	on attribute column values
       Spearfish example with  automated  elevation  extraction	 for  vertical
       shift:
       # work on own map copy:
       g.copy vect=archsites@PERMANENT,myarchsites
       # add new 'zs' column to	later store height of each site:
       v.db.addcolumn myarchsites col="zs double precision"
       # set region to elevation map and fetch individual heights:
       g.region	raster=elevation.10m -p
       v.what.rast myarchsites rast=elevation.10m col=zs
       # verify:
       v.db.select myarchsites
       # perform transformation	to 3D
       v.transform -t myarchsites output=myarchsites3d column="zshift:zs" layer=1
       # drop table containing transformation parameters
       v.db.dropcolumn myarchsites3d col=zs
       The resulting map is a 3D vector	map.

SEE ALSO
	m.transform, i.rectify,	v.rectify, r.region

AUTHOR
       Radim Blazek, ITC-irst, Trento, Italy,
       Column  support	added  by  Martin Landa, FBK-irst (formerly ITC-irst),
       Trento, Italy (2007/09)

SOURCE CODE
       Available at: v.transform source	code (history)

       Main index | Vector index | Topics index	| Keywords index  |  Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.4 Reference	Manual

GRASS 7.8.4							v.transform(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLE | SEE ALSO | AUTHOR | SOURCE CODE

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