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

ectangular because there might be some missing tiles and they might be different sizes. Tiles
of the table are not the same size and do not overlap.
Figure 4.34: Irregular tiled raster coverage (36 tiles))[6].
3. A raster table may be a regular tiled raster coverage. However, its extent might not necessarily
be rectangular when there are some missing tiles. Tiles should be the same size and do not
overlap.
Figure 4.35: Regular tiled raster coverage (36 tiles) [6].
4. A raster table may be a rectangular regular tiled raster coverage. Its extent is necessarily
rectangular and there are no missing tiles. These tiles are all the same size and do not overlap.
This is the traditional way of displaying a coverage.
Figure 4.36: Rectangular regular tiled raster coverage (54 tiles) [6].
5. A raster table is a tiled image (using the option -k when loading the image). Its extent is
necessarily rectangular and there are no missing tiles. These tiles are all the same size and do
not overlap. This type is different from type 4. in that it does not represent a complete coverage.
Other images forming the rest of the coverage are stored as tiled images in other tables.
PostGIS Raster provides the padding mechanism to support regular tiled raster images (or
regular blocking raster images) because raster applications are often optimized to deal with
arrangements 3., 4. and 5..
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