.TH v.proj 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBv.proj\fR\fR  \- Re\-projects a vector map from one location to the current location.
.SH KEYWORDS
vector, projection, transformation, import
.SH SYNOPSIS
\fBv.proj\fR
.br
\fBv.proj \-\-help\fR
.br
\fBv.proj\fR [\-\fBlzwb\fR] \fBlocation\fR=\fIname\fR  [\fBmapset\fR=\fIname\fR]   [\fBinput\fR=\fIname\fR]   [\fBdbase\fR=\fIpath\fR]   [\fBsmax\fR=\fIfloat\fR]   [\fBoutput\fR=\fIname\fR]   [\fBpipeline\fR=\fIstring\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-l\fR" 4m
.br
List vector maps in input mapset and exit
.IP "\fB\-z\fR" 4m
.br
Assume z coordinate is ellipsoidal height and transform if possible
.br
3D vector maps only
.IP "\fB\-w\fR" 4m
.br
Disable wrapping to \-180,180 for latlon output
.br
Latlon output only, default is \-180,180
.IP "\fB\-b\fR" 4m
.br
Do not build vector topology
.br
Recommended for massive point projection
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.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 "\fBlocation\fR=\fIname\fR \fB[required]\fR" 4m
.br
Location containing input vector map
.br
Location name (not location path)
.IP "\fBmapset\fR=\fIname\fR" 4m
.br
Mapset containing input vector map
.br
Default: name of current mapset
.IP "\fBinput\fR=\fIname\fR" 4m
.br
Name of input vector map to re\-project
.IP "\fBdbase\fR=\fIpath\fR" 4m
.br
Path to GRASS database of input location
.br
Default: path to the current GRASS GIS database
.IP "\fBsmax\fR=\fIfloat\fR" 4m
.br
Maximum segment length in meters in output vector map
.br
Increases accuracy of reprojected shapes, disable with smax=0
.br
Default: \fI10000\fR
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output vector map (default: input)
.IP "\fBpipeline\fR=\fIstring\fR" 4m
.br
PROJ pipeline for coordinate transformation
.SH DESCRIPTION
\fIv.proj\fR 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
corresponding PROJ_INFO files). The projection information is taken from the
current PROJ_INFO files, as set and viewed with
\fIg.proj\fR.
.SH NOTES
If \fBoutput\fR is not specified it is set to be the same as input map
name.
.br
If \fBmapset\fR is not specified, its name is assumed to be the same
as the current mapset\(cqs name.
.br
If \fBdbase\fR is not specified it is assumed to be the current
database. The user only has to specify \fBdbase\fR if the source
location is stored in another separate GRASS database.
.br
If \fBsmax\fR is set to \fB0\fR the automated vertex densification is
disabled (not recommended).
.PP
\fIv.proj\fR supports general datum transformations, making use of the
\fIPROJ\fR co\-ordinate system translation library.
.PP
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 \fB\-w\fR flag.
.PP
When reprojecting massive point clouds for which topology is not necessary,
the user can set the \fB\-b\fR flag to suppress the building of topology of
the output map.
.PP
In order to preserve spatial detail, \fIv.proj\fR performs automated
vertex densification (as an alternative, \fIv.split\fR
could be used before reprojecting. Without vertex densification, depending on
the source and target 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
topological errors.
.SH EXAMPLES
.br
.nf
\fC
v.proj in=mymap location=latlong mapset=user1
\fR
.fi
.SH REFERENCES
.IP
.IP \fB1\fR
Evenden, G.I.  (1990) Cartographic
projection procedures for the UNIX environment \- a user\(cqs manual.
USGS Open\-File Report 90\-284 (OF90\-284.pdf)
See also there: Interim Report and 2nd Interim Report on Release 4, Evenden 1994).
.IP \fB2\fR
Richards, John A. (1993), Remote Sensing Digital Image Analysis,
Springer\-Verlag, Berlin, 2nd edition.
.PP
PROJ: Projection/datum support library.
.PP
\fBFurther reading\fR
.RS 4n
.IP \(bu 4n
ASPRS Grids and Datum
.IP \(bu 4n
Projections Transform List (PROJ)
.IP \(bu 4n
Coordinate operations by PROJ (projections, conversions, transformations, pipeline operator)
.IP \(bu 4n
MapRef \-
The Collection of Map Projections and Reference Systems for Europe
.IP \(bu 4n
Information and Service System for European Coordinate Reference Systems \- CRS
.IP \(bu 4n
Cartographical Map Projections by Carlos A. Furuti
.RE
.SH SEE ALSO
\fI
g.proj,
m.proj,
r.proj,
i.rectify,
r.stats,
v.sample,
v.split,
v.surf.idw,
v.surf.rst
\fR
.SH AUTHORS
Irina Kosinovsky, US ARMY CERL
.br
M.L. Holko, USDA, SCS, NHQ\-CGIS
.br
R.L. Glenn, USDA, SCS, NHQ\-CGIS
.SH SOURCE CODE
.PP
Available at: v.proj source code (history)
.PP
Main index |
Vector index |
Topics index |
Keywords index |
Graphical index |
Full index
.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual