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v.proj(1) Grass User's Manual v.proj(1)

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

vector, projection, transformation, import

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

-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

location=name [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)

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 corresponding PROJ_INFO files). The projection information is taken from the current PROJ_INFO files, as set and viewed with g.proj.

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 another 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.4 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 necessary, 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 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.

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

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 Interim Report on Release 4, Evenden 1994).
2
Richards, John A. (1993), Remote Sensing Digital Image Analysis, Springer-Verlag, Berlin, 2nd edition.
PROJ 4: Projection/datum support library.
Further reading
ASPRS Grids and Datum
Projections Transform List (PROJ.4)
MapRef - The Collection of Map Projections and Reference Systems for Europe
Information and Service System for European Coordinate Reference Systems - CRS
Cartographical Map Projections by Carlos A. Furuti

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

Irina Kosinovsky, US ARMY CERL
 
M.L. Holko, USDA, SCS, NHQ-CGIS
 
R.L. Glenn, USDA, SCS, NHQ-CGIS
Last changed: $Date: 2016-12-01 12:04:19 +0100 (Thu, 01 Dec 2016) $

Available at: v.proj source code (history)
Main index | Vector index | Topics index | Keywords index | Graphical index | Full index
© 2003-2018 GRASS Development Team, GRASS GIS 7.4.3 Reference Manual
GRASS 7.4.3

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