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GRASS 6 comes with a completely overhauled vector engine which is extended to manage 2D and 3D topological vector data. The new internal vector data format is now portable between 32bit and 64bit platforms. In addition, a new spatial indexing system accelerates vector data access and a category indexing system accelerates attribute queries. Vector data from other GIS software can be imported (allowing for topological data clean-up) as well as live-linked into the GRASS database as virtual maps. The new integrated Directed Graph Library provides support for vector network analysis. Vector map overlays, intersections and extraction of features are implemented. The new vector engine includes full and flexible integration of database management systems (DBMS) for attribute management (currently DBF, PostgreSQL, mySQL, and ODBC are supported). SQL statements are used to manage attributes. Graphical updating of vector attributes has been implemented as well in the interactive vector query tool.
In this section we will explore basic vector functionality.
Supported geometry types are point, centroid, line, boundary, area (boundary + centroid), face (3D area), kernel (3D centroid), and volumes (faces + kernel). Geometry storage is true 3D: x, y, z with z=0 in the 2D case.