v.proj(1grass) | Grass User's Manual | v.proj(1grass) |
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] [pipeline=string]
[--overwrite] [--help] [--verbose] [--quiet]
[--ui]
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
PROJ 4: Projection/datum support library.
Further reading
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)
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