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


       vector, projection, transformation, import


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

           List vector maps in input mapset and exit

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

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

           Do not build vector topology
           Recommended for massive point projection

           Allow output files to overwrite existing files

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

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

           Mapset containing input vector map
           Default: name of current mapset

           Name of input vector map to re-project

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

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

           Name for output vector map (default: input)

           PROJ pipeline for coordinate transformation


       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
       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,,


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


       Available at: v.proj source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual