vectorascii(1grass) GRASS GIS User's Manual vectorascii(1grass)
GRASS ASCII vector format specification
A vector map in GRASS native vector format may contain a mix of primi-
tives 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 con-
tains 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 (op-
tionally) 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 de-
grees must be positive or negative instead of using a hemisphere let-
ter. 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 (his-
tory)
Accessed: unknown
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GRASS 7.8.7 vectorascii(1grass)
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