PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

Figure 5.8: Gird of cells of USA map [23].
• PostGIS provides several storage solutions for applications whether they are read-only applications
(storing out-database raster) or editing and analysis applications (storing in-database
raster).
With out-database raster, image files (JPEGs) can be stored as they are in any GDAL format.
So it speeds up geoprocessing (a GIS operation used to manipulate spatial data) by providing
direct access for web applications.
The traditional in-database raster, that stores raster data as a grid of pixel values, is intended
for analysis operations that require working on pixel values. Obviously, execution time of these
operations are faster than ones executed on out-database rasters since there is no need to extract
the pixel values from an image file (such as JPEG, TIFF and etc).
Lightweight Multi-users
As all geoprocessing is done in the database, these processes thus are kept close to the data where
the data should be (in a database). Hence, desktop and web GIS applications become simple SQL
query builders and data viewers.
Figure 5.9: Web GIS application [23].
71