Changes between Version 48 and Version 49 of frmts_wtkraster.html


Ignore:
Timestamp:
Mar 8, 2012, 4:33:17 AM (12 years ago)
Author:
jorgearevalo
Comment:

Updated GDAL raster reading information

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  • frmts_wtkraster.html

    v48 v49  
    9999Note that the string, up to the part starting with "table='" is a libpq-style [http://www.gdal.org/ogr/drv_pg.html connection string]. That means that you can leave out unnecessary fields (like password, in some cases).
    100100
    101 The "table" option requires the name of a WKT Raster table. This table only can be created by using the script ''gdal2tiles'', by now.
     101The "table" option requires the name of a PostGIS Raster table. This table was created when the roaster was loaded.
    102102
    103103The "where" option is used to filter the results of the raster table. Any SQL-WHERE expression is valid. The "mode" option is used to know the expected arrangement of the raster table. There are 2 possible values:
    104104
    105105 * mode = 1. Also called ''ONE_RASTER_PER_ROW'' mode. In this case, a raster table is considered as a bunch of different raster files. This mode is intended for raster tables storing different raster files. It's the default mode if you don't provide this field in connection string.
    106  * mode = 2. Also called ''ONE_RASTER_PER_TABLE'' mode. In this case, a raster table is considered as a unique raster file, even if the table has more than one row. This mode is intended for reading tiled rasters from database, just like the rasters created in section 3.1.
     106 * mode = 2. Also called ''ONE_RASTER_PER_TABLE'' mode. In this case, a raster table is considered as a unique raster file, even if the table has more than one row. This mode is intended for reading tiled rasters from database.
    107107
    108108Three important notes here:
    109  * If a table stores a tiled raster (like ones created in section 3.1) and you execute the driver with mode = 1, each image tile will be considered as a different image, and will be reported as a subdataset.
     109 * If a table stores a tiled raster and you execute the driver with mode = 1, each image tile will be considered as a different image, and will be reported as a subdataset.
    110110 * There are use cases the driver can't still work with. For example: non-regular blocked rasters. That cases are detected and an error is raised. Anyway, as I've said, the driver is under development, and will work with more raster arrangements ASAP.
    111111 * There's an additional working mode. If you don't provide a table name, the driver will look for existing raster tables in all allowed database' schemas, and will report each table as a subdataset.
    … …  
    113113You must use this connection string's format in all the gdal tools, like gdalinfo, gdal_translate, gdalwarp, etc.
    114114
    115 '''Example 1:'''
    116 
    117 To get info about ''utm.tif'' file stored in database (see section 3.1) run this command:
    118 
    119 {{{
    120 >$ gdalinfo -mm -stats -checksum "PG:host='localhost' dbname='<raster_database>' user='<user>' password='<password>' table='utm' mode='2'"
    121 }}}
    122 
    123 As user / password, in a typical installation, you can use '''postgres / postgres'''
    124 
    125 
    126 '''Example 2:'''
    127 
    128 To get an overview of the ''katrina.tif'' image with half size run this command:
    129 
    130 {{{
    131 >$ gdal_translate -outsize 50% 50% "PG:host='localhost' dbname='<raster_database>' user='<user>' password='<password>' table='katrina' mode='2'" katrina_half_size.tif
    132 }}}
    133 
    134 This will create a file called ''katrina_half_size.tif'' like the original ''katrina.tif'' but half size.
     115To see examples, check the PostGIS Raster FAQ section: [http://postgis.refractions.net/documentation/manual-svn/RT_FAQ.html#id3076646 Can I export my PostGIS Raster data to other raster formats?]
    135116
    136117