v.external(1)

1v.external(1)                 Grass User's Manual                v.external(1)
2
3
4

NAME

6       v.external  - Creates a new vector as a read-only link to OGR layer.
7       Available       drivers:       ESRI      Shapefile,MapInfo      File,UK
8       .NTF,SDTS,TIGER,S57,DGN,VRT,REC,Memory,BNA,CSV,GML,GPX,KML,GeoJ‐
9       SON,Interlis      1,Interlis     2,GMT,SQLite,DODS,ODBC,PGeo,OGDI,Post‐
10       greSQL,MySQL,PCIDSK,XPlane,AVCBin,AVCE00,DXF,GRASS,Geocon‐
11       cept,GeoRSS,GPSTrackMaker,VFK
12

KEYWORDS

14       vector
15

SYNOPSIS

17       v.external
18       v.external help
19       v.external  dsn=string   [output=name]   [layer=string]   [--overwrite]
20       [--verbose]  [--quiet]
21
22   Flags:
23       --overwrite
24           Allow output files to overwrite existing files
25
26       --verbose
27           Verbose module output
28
29       --quiet
30           Quiet module output
31
32   Parameters:
33       dsn=string
34           OGR datasource name. Examples:
35                     ESRI    Shapefile:    directory     containing     shape‐
36           files        MapInfo File: directory containing mapinfo files
37
38       output=name
39           Output vector. If not given, available layers are printed only.
40
41       layer=string
42           OGR  layer  name.  If not given, available layers are printed only.
43           Examples:
44                     ESRI  Shapefile:  shapefile  name          MapInfo  File:
45           mapinfo file name
46

DESCRIPTION

48       v.external  creates  new  vector  as a link to external OGR layer (read
49       only).  OGR (Simple Features Library) is part of the GDAL  library,  so
50       you need to install GDAL to use v.external and external OGR layers.
51
52   Supported OGR Vector Formats
53       ESRI Shapefile
54       Mapinfo File
55
56       Further available drivers such as UK .NTF, SDTS, TIGER, IHO S-57 (ENC),
57       DGN, GML, AVCBin, REC, Memory, OGDI, and PostgreSQL depend on the local
58       installation (OGR library), for details see OGR web site.
59

EXAMPLES

61       SHAPE files
62
63       v.external dsn=/home/user/shape_data layer=test_shape output=grass_map
64
65
66       MapInfo files
67
68       v.external dsn=./ layer=mapinfo_test output=grass_map
69
70
71       SDTS files (you have to select the CATD file)
72
73       v.external dsn=CITXCATD.DDF output=cities
74
75
76       TIGER files
77
78       v.external     dsn=input/2000/56015/    layer=CompleteChain,PIP    out‐
79       put=t56015_all
80
81
82       PostGIS maps (area example)
83
84       v.external   dsn="PG:host=localhost    user=postgres    dbname=postgis"
85       layer=polymap \
86       output=polygons
87
88

NOTES

90       The  simple  feature  data model used by OGR is very different from the
91       topological format used by GRASS. Instead of true topology,  so  called
92       'pseudo  topology'  is  created  for  data  linked by v.external.  User
93       should learn the difference between those to formats, because some mod‐
94       ules  working  correctly  with  GRASS  native  data,  can produce wrong
95       results with input layers created by v.external.
96
97       See v.db.connect for an example of maintaining attributes  in  external
98       DBMS in also writeable mode.
99

REFERENCES

101       OGR vector library
102       OGR vector library C API documentation
103

AUTHOR

108       Radim Blazek, ITC-Irst, Trento, Italy
109
110       Last changed: $Date: 2006-03-21 19:22:37 +0100 (Tue, 21 Mar 2006) $
111
112       Full index
113
114       © 2003-2008 GRASS Development Team
115
116
117
118GRASS 6.3.0                                                      v.external(1)