Database Reference
In-Depth Information
There are a few keywords used in this chapter and in the PostGIS ecosystem that
need to be defined:
•
raster
: Thisis the PostGIS data type for storing raster files in PostgreSQL.
•
tile
:Thisisasmallchunkoftheoriginalrasterfiletobestoredinonecolumn
of a table's row. Each tile has its own set of spatial information and thus is
independentofalltheothertilesinthesamecolumnofthesametable,even
if the other tiles are from the same original raster file.
•
coverage
: This consists of all the tiles of a single raster column from one
table.
WemakeheavyuseofGDALinthischapter.GDALisgenerallyconsideredthede
factoSwissArmyKnifeforworkingwithrasters.GDALisnotasingleapplicationbut
isaraster-abstractionlibrarywithmanyusefulutilities.ThroughGDAL,youcanget
themetadataofaraster,convertthatrastertoadifferentformat,andwarpthatras-
ter among many other capabilities. For our needs in this chapter, we will use three
GDAL utilities:
gdalinfo
,
gdalbuildvrt
, and
gdal_translate
.
