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A more complex task could be that the user wants to find out all
images (maybe hundreds or more) inside a specific region and
then generate full pyramids for each of the images. The
following simple PL/SQL block would do the work
automatically.
declare
type curtype is ref cursor;
my_cursor curtype;
stmt varchar2(1000);
id number;
gr sdo_georaster;
gm sdo_geometry;
begin
— 1. define the query area in WGS84 coordinate system
gm := sdo_geometry(2003, 8307, null,
sdo_elem_info_array( 1,1003,3),
sdo_ordinate_array(5,6,30,30));
— 2. define the query statement on the georaster table
stmt := 'select id, t.myimage from my table t' ||
'where sdo_inside(t.my_image.spatialextent, :1)-'TRUE'";
— 3. spatially query all images INSIDE the query area
— and generate full pyramids for each of the images
open my_cursor for stmt using gm;
loop
fetch my_cursor into id, gr;
exit when my_cursor%NOTFOUND;
sdo_geor.generatePyramid(gr, 'resampling=bilinear');
execute immediate 'update my_table set my_image=:l
where id=:2' using gr, id;
commit;
end loop;
close my cursor;
end;
computing systems. With a multi-tier architecture and the
power of GRID computing, concurrent processing and
parallelization can be readily available for raster image database
management and processing.
7. CONCLUSIONS
In summary, this enterprise database-centric approach provides
a foundation to help solve the two major challenges in a truly
secure, scalable and performant way and offers an easy-to-use
interface to empower non-geospatial professionals to manage
and process geospatial raster datasets. The implementation of
Oracle GeoRaster based on this database-centric approach and
the tests we conducted show that this database-centric approach
is a viable solution for geospatial image management and
processing.
This approach focuses on the database server, in which the
future directions include content-based indexing and search,
componentizing the server-side image processing and query
engine and storing them as database models, enhancing raster
data analysis and mining, leveraging computing clusters and
parallelizing image processing operations. It is not to discount
the middleware image servers and desktop image processing
systems or GIS systems. Instead the spatially enabled database
server, middleware application servers and desktop image
processing and GIS systems should complement each other and
built on top of them a distributed system with a multi-tier
architecture is the right direction.
ACKNOWLEDGEMENTS
The authors would like to thank Zhun Li for conducting some
of the tests presented in this paper.
REFERENCES
Users can also wrap up such blocks into a PL/SQL procedure
and store it in the database, then call the stored procedure
directly. Such features enable users to organize complex
processes and automate database administration tasks easily.
This API enables non-geospatial experts understand such
geospatial databases and the data manipulations and thus
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