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

NAME
       v.proj  - Re-projects a vector map from one location to the current lo-
       cation.

KEYWORDS
       vector, projection, transformation, import

SYNOPSIS
       v.proj
       v.proj --help
       v.proj	 [-lzwb]    location=name     [mapset=name]	  [input=name]
       [dbase=path]	 [smax=float]	   [output=name]     [pipeline=string]
       [--overwrite]  [--help]	[--verbose]  [--quiet]	[--ui]

   Flags:
       -l
	   List	vector maps in input mapset and	exit

       -z
	   Assume z coordinate is ellipsoidal height and transform if possible
	   3D vector maps only

       -w
	   Disable wrapping to -180,180	for latlon output
	   Latlon output only, default is -180,180

       -b
	   Do not build	vector topology
	   Recommended for massive point projection

       --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:
       location=nameA [required]
	   Location containing input vector map
	   Location name (not location path)

       mapset=name
	   Mapset containing input vector map
	   Default: name of current mapset

       input=name
	   Name	of input vector	map to re-project

       dbase=path
	   Path	to GRASS database of input location
	   Default: path to the	current	GRASS GIS database

       smax=float
	   Maximum segment length in meters in output vector map
	   Increases accuracy of reprojected shapes, disable with smax=0
	   Default: 10000

       output=name
	   Name	for output vector map (default:	input)

       pipeline=string
	   PROJ	pipeline for coordinate	transformation

DESCRIPTION
       v.proj allows a user to convert a vector	map in a specified mapset of a
       specified  location  (different	from current) with projection of input
       location	to the vector map in a current mapset of current location with
       projection  of current location (both projections are defined by	corre-
       sponding	PROJ_INFO files). The projection information is	taken from the
       current PROJ_INFO files,	as set and viewed with g.proj.

NOTES
       If output is not	specified it is	set to be the same as input map	name.
       If  mapset  is not specified, its name is assumed to be the same	as the
       current mapset's	name.
       If dbase	is not specified it is assumed to be the current database. The
       user  only has to specify dbase if the source location is stored	in an-
       other separate GRASS database.
       If smax is set to 0 the automated vertex	densification is disabled (not
       recommended).

       v.proj  supports	 general datum transformations,	making use of the PROJ
       co-ordinate system translation library.

       When projecting into a latlon location, east coordinates	are wrapped by
       the proj4 library to fit	into the range -180,180. This is in most cases
       appropriate, but	can cause errors the input vector  crosses  the	 datum
       line  at	 180E/W. In this case wrapping of east coordinates to -180,180
       needs to	be disabled with the -w	flag.

       When reprojecting massive point clouds for which	topology is not	neces-
       sary, the user can set the -b flag to suppress the building of topology
       of the output map.

       In order	to preserve spatial detail, v.proj performs  automated	vertex
       densification  (as  an alternative, v.split could be used before	repro-
       jecting.	Without	vertex densification, depending	on the source and tar-
       get  CRS	(Coordinate Reference System), geometries can be substantially
       deformed	(straight lines	 become	 curves,  squares  become  trapezoids,
       etc).  The densification	of linear features can help to avoid topologi-
       cal errors.

EXAMPLES
       v.proj in=mymap location=latlong	mapset=user1

REFERENCES
       1      Evenden, G.I.  (1990) Cartographic projection procedures for the
	      UNIX  environment	 -  a  user's  manual.	 USGS Open-File	Report
	      90-284 (OF90-284.pdf) See	also there: Interim Report and 2nd In-
	      terim Report on Release 4, Evenden 1994).

       2      Richards,	John A.	(1993),	Remote Sensing Digital Image Analysis,
	      Springer-Verlag, Berlin, 2nd edition.

       PROJ: Projection/datum support library.

       Further reading

	   o   ASPRS Grids and Datum

	   o   Projections Transform List (PROJ)

	   o   Coordinate operations by	PROJ (projections, conversions,	trans-
	       formations, pipeline operator)

	   o   MapRef  -  The Collection of Map	Projections and	Reference Sys-
	       tems for	Europe

	   o   Information and Service System for European  Coordinate	Refer-
	       ence Systems - CRS

	   o   Cartographical Map Projections by Carlos	A. Furuti

SEE ALSO
	  g.proj,  m.proj,  r.proj,  i.rectify,	 r.stats,  v.sample,  v.split,
       v.surf.idw, v.surf.rst

AUTHORS
       Irina Kosinovsky, US ARMY CERL
       M.L. Holko, USDA, SCS, NHQ-CGIS
       R.L. Glenn, USDA, SCS, NHQ-CGIS

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

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

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.5 Reference	Manual

GRASS 7.8.5							     v.proj(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | REFERENCES | SEE ALSO | AUTHORS | SOURCE CODE

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