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

DROP INDEX spain_images_idx;
CREATE INDEX spain_images_idx
ON spain_images(image.spatialExtent)
INDEXTYPE IS mdsys.spatial_index;
In contrast, PostGIS Raster loads raster data and creates spatial index using simply these two
commands:
python raster2pgsql.py -r *.tif -t spain_images -s 4326 -k 50x50 -I -o spain.sql
psql -d postgis_db -f spain.sql
The first command uses Python loader to import a set of raster images into raster table spain_images
(option -t). Option -I is used to create indexes over these rasters. All necessary code is created and
registered in a SQL file spain.sql (option -o). Then, the second command will execute spain.sql
in PostGIS database.
3.2.4 Overlapping Raster and Vector Layers
Each spatial instance has a spatial reference identifier (SRID). However, the result of any spatial
method from two spatial instances is valid only if those instances that have the same SRID. It is the
same in the case of overlapping operation between vector and raster data.
To reset SRID of a geometry object, GeoRaster uses sdo_cs.transform() function [14]:
SELECT sdo_cs.transform(geom, srid_number) geom FROM geom_table ;
In the same way in PostGIS Raster:
SELECT ST_Transform(the_geom, srid_number)) FROM geom_table;
3.2.5 Loading Raster Data
Loading Using Oracle GeoRaster
To load raster image into GeoRaster, firstly users need to create tables to store the raster data.
One table stores the metadata and another one stores the data [14]:
CREATE TABLE spain_images (image_id NUMBER PRIMARY KEY,
image_description VARCHAR2(50), image SDO_GEORASTER);
CREATE TABLE spain_images_rdt OF SDO_RASTER
(PRIMARY KEY (rasterID, pyramidLevel, bandBlockNumber, rowBlockNumber,
columnBlockNumber))
TABLESPACE users LOB(rasterBlock) STORE AS SECUREFILE lobseg (NOCACHE);
Then, the image is loaded using PL/SQL code:
DECLARE
geor SDO_GEORASTER;
BEGIN
-- Initialize an empty GeoRaster object into which the external image
-- is to be imported.
INSERT INTO spain_images
VALUES( 1, ’Spain_TIFF_1’, sdo_geor.init(’spain_images_rdt’) );
-- Import the TIFF image.
SELECT image INTO geor FROM spain_images
WHERE image_id = 1 FOR UPDATE;
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