Changes between Version 5 and Version 6 of UsersWikiCoveragesAndPostgis

Timestamp:

Jul 21, 2011, 4:29:43 PM (13 years ago)

Author:

bnordgren

Comment:

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UsersWikiCoveragesAndPostgis

@@ -57 +57 @@
 === Raster Coverages ===
 
-Raster coverages are backed by regularly gridded data. The ''domain'' is always a point. The ''range'' is one or more numeric values, referred to as "bands". Text values and timestamp values are not allowed. One can convert this gridded data into table form, if desired, although this is almost never useful. Simply construct a table with one `geometry` column and one numeric column for each band. Each cell in the table may then be represented by its own row. The principal advantage of the regular gridded structure is the ease with which relevant data can be located, given a spatial region of interest. This structure allows certain optimizations for speed which are not possible using a collection of data in table form.
+Raster coverages are backed by regularly gridded data. The ''domain'' is always a point. The ''range'' is one or more numeric values, referred to as "bands". Text values and timestamp values are not allowed. One can convert this gridded data into table form, if desired, although this is almost never useful. Simply construct a table with one `geometry` column for the cell coordinates and one numeric column for each band. Each cell in the table may then be represented by its own row. The principal advantage of the regular gridded structure is the ease with which relevant data can be located, given a spatial region of interest. This structure allows certain optimizations for speed which are not possible using a collection of data in table form.
 
 In PostGIS, the data required to back a raster coverage is contained in a single data type called `raster`. This single type has both location information and value information. Each point within a raster can have it's own set of values. This subtle point has some not-so-subtle implications.