GRASS 6 Tutorial/Vector data management

Vector data management

Overview

The native GRASS vector format provides:

• Vector topology
• m:n mapping of geometry features to attributes
• Vector layers
• OGC Simple Features <-> Topological Vector Conversion
• Database Management system (DBMS)
• SQLite, PostgreSQL + PostGIS, MySQL, ODBC (, DBF)

The vector geometry types supported in GRASS includes:

• Point
• Centroid
• Line
• Boundary
• Area (Boundaries + Centroid)
• Face (3D Area)
• [Kernel (3D Centroid)]
• [Volumes (Faces + Kernel)]

All types are true 3D: x,y,z

Import/Export of Vector data

The GRASS modules v.in.* and v.out.* handle the importing and exporting of Vector datasets. v.in.ogr is widely used and has simplified the import of vector data; OGR itself support a wide range of formats. v.out.ogr always exports the entire vector map

Importing an ESRI Shapefile

The following code snippet is a simple usage of v.in.ogr, which imports an ESRI Shapefile from the command line as follows:

v.in.ogr dsn=boundary_county.shp out=boundary_county 

However, v.in.ogr has many options to import subsets (defined spatially or by SQL) and vector types

The same can be achieved using the GRASS Graphical Interface. The Vector import interface can be accessed through the vector layer manager:

Introductory information on vector data processing is available from the help manual.

Grass Six Tutorial Default Settings

      -  Default settings for vector geometry;
         for vector attributes; for db.* modules

Grass Six Tutorial Geometry Management

http://grass.osgeo.org/grass57/tutorial/geom_storage.html

       -  General notes on Geometry 
         management; Managing the default settings; 
         GRASS vector architecture; Geometry stored in native format;
         Geometry stored in SHAPE file; 
         Import/export of vector data Geometry;
         Generating vector geometry from various sources

Grass Six Tutorial Attribute Management

http://grass.osgeo.org/grass57/tutorial/attrib_storage.html

       - General notes on Attribute 
         management; Managing the default settings; Examples;
         Database Schema