vectorascii(1)

📦
version 8.4.2 · 7 versions
, in fedora 44

🦋 GRASS ASCII VECTOR FORMAT SPECIFICATION 🦋

okay bestie, sit down, hydrate, because this is vectorascii(1) from the GRASS GIS User's Manual and it is genuinely so much fun once it clicks 🫶

💖 the whole vibe 💖

A vector map in GRASS native vector format may contain a mix of primitives — and before you panic, "primitives" just means the lil building blocks: points, lines, boundaries, centroids, areas, faces, and kernels, all coexisting in one file like a very well-behaved group chat. The GRASS ASCII vector format may contain also a header with various metadata (peep the example down below 👀).

🎀 the header (aka the metadata moment) 🎀

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 (where it gets real) ✨

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 — so if you don't see it, that's not a bug, that's just the format being chill 💅

🔥 the primitive codes 🔥

  • '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
ngl, if you're reaching for 'A', just use 'B' instead. 'A' is lowkey just here for the nostalgia 💀

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).

🧭 coordinate order 🧭

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
not me living through the Y X era 😭 if you're reading ancient data, check which order you're actually in before you trust a single vertex.

🌍 latitude/longitude formats 🌍

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).

so basically: two outlines, two lil center dots, and the centroids are the ones holding the category IDs 🍓

👑 SEE ALSO 👑

  • v.in.ascii
  • v.out.ascii
  • v.edit
  • v.support

💜 SOURCE CODE 💜

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

Accessed: Friday Nov 21 14:02:57 2025

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

and that's the whole page, bestie ✨ © 2003-2025 GRASS Development Team, GRASS GIS 8.4.2 Reference Manual — this one's from GRASS 8.4.2 and it's the vectorascii(1) page, so go forth and read your ASCII vectors with main character energy 💅🎀🦋

📦 where this page comes from