Developing Map Databases: Problems and Solutions - Maps for the Future Children Education and Internet - page 144

12.3.2 Storage of Vector Maps

There are various kinds of vector maps, and they are built up on different logic.
Their models are much more complicated than that the raster data models. This
explains why the present 3.0 version of the EDIT system does not store the vector
maps organized in relation tables, but in the file system in a hierarchical structure.
When planning the system, its simple use was highly considered, and the table
structure designed for the raster data was not used for the vector subsystem.
Figure 12.4 presents a vector layer of the borders of blocks in Budapest, which
can be accessed by a hierarchic control (Tree View) shown in the figure. The layers
are sometimes grouped according to a region they belong to (e.g., budapest ),
sometimes according to the name of data products (e.g., ADC-WorldMap).
The layers of the vector subsystem are available in ESRI shape or Mapinfo tab
formats. Although there are other file formats (e.g., ArcInfo personal database in
mdb file formats), we decided that these two standard formats provide the system
with enough flexibility, because every GIS software can now read or import these
file formats.

12.3.3 Query from the Database

You can search in the raster subsystem according to the SQL (structured query
language) standard. The full functions of this kind of online search are only

Fig. 12.4 Navigation in the vector subsystem with a hierarchic control