GRASS ASCII vector format specification

       A  vector  map  in  GRASS  native  vector format may contain a mix of primitives including points, lines,
       boundaries, centroids, areas, faces, and kernels. The GRASS ASCII vector format may contain also a header
       with various metadata (see example below).

       The  header is similar as the head file of vector binary format but contains bounding box also. Key words
       are:
       ORGANIZATION
       DIGIT DATE
       DIGIT NAME
       MAP NAME
       MAP DATE
       MAP SCALE
       OTHER INFO
       ZONE
       WEST EDGE
       EAST EDGE
       SOUTH EDGE
       NORTH EDGE
       MAP THRESH

       The body begins with the row:
       VERTI:
       followed by records of primitives:
       TYPE NUMBER_OF_COORDINATES [NUMBER_OF_CATEGORIES]
        X Y [Z]
       ....
        X Y [Z]
       [ LAYER CATEGORY]
       ....
       [ LAYER CATEGORY]
       Everything above in [ ] is optional.

       The primitive codes are as follows:

           •   ’P’: point

           •   ’L’: line

           •   ’B’: boundary

           •   ’C’: centroid

           •   ’F’: face (3D boundary)

           •   ’K’: kernel (3D centroid)

           •   ’A’: area (boundary) - better use ’B’; kept only for backward compatibility
       The coordinates are listed following the initial line containing the primitive code, the total number  of
       coordinates  in  the  series, and (optionally) the number of categories (1 for a single layer, higher for
       multiple layers).  Below that 1 or several lines follow to indicate the layer  number  and  the  category
       number (ID).

       The order of coordinates is
       X Y [Z]
       In pre-GRASS 6 versions of the ASCII format, the order of coordinates was different:
       Y X

       Latitude/Longitude  data  may be given in a number of ways.  Decimal degrees must be positive or negative
       instead of using a hemisphere letter. Mixed coordinates must use a hemisphere letter. Whole  minutes  and
       seconds must always contain two digits (example: use 167:03:04.567; and not 167:3:4.567).
       Acceptable formats:
       key: D=Degrees; M=Minutes; S=Seconds; h=Hemisphere (N,S,E,W)

           •   (+/-)DDD.DDDDD

           •   DDDh

           •   DDD:MMh

           •   DDD:MM.MMMMMh

           •   DDD:MM:SSh

           •   DDD:MM:SS.SSSSSh

EXAMPLES

       ORGANIZATION: GRASS Development Team
       DIGIT DATE:   1/9/2005
       DIGIT NAME:   -
       MAP NAME:     test
       MAP DATE:     2005
       MAP SCALE:    10000
       OTHER INFO:   Test polygons
       ZONE:  0
       MAP THRESH:   0.500000
       VERTI:
       B  6
        5958812.48844435 3400828.84221011
        5958957.29887089 3400877.11235229
        5959021.65906046 3400930.7458436
        5959048.47580612 3400973.65263665
        5959069.92920264 3401032.64947709
        5958812.48844435 3400828.84221011
       C  1 1
        5958952.42189184 3400918.23126419
        1 20
       B  4
        5959010.9323622 3401338.36037757
        5959096.7459483 3401370.54047235
        5959091.38259917 3401450.99070932
        5959010.9323622 3401338.36037757
       C  1 1
        5959063.08352122 3401386.98533277
        1 21
       In  this  case  the  vector  map  contains  2  boundaries  (first boundary with 6 vertices, second with 4
       vertices) without category and 2 centroids with category number 20 and 21 (layer 1).

SEE ALSO

        v.in.ascii, v.out.ascii, v.edit

SOURCE CODE

       Available at: GRASS ASCII vector format specification source code (history)

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

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