Hi Christian, I would also like to mention that in our experience, we have seen clients with large scale (1K by 1K tiles), national coverage raster datasets, which are updated every 6 weeks. In this scenario, AFAIK, creating a mosaic for the whole country is not optimum, as if only one tile needs updating, then the whole mosaic would need to be re-created. There can also be a constraint against disk space.
Many thanks, Steve -----Original Message----- From: Thelen, Bruce [mailto:bthe...@corelogic.com] Sent: 05 May 2010 14:22 To: christian.muel...@nvoe.at; Baskar, Dhanapal Cc: geotools-devel@lists.sourceforge.net Subject: Re: [Geotools-devel] Proposed Mosaicing GeoRaster Module Christian, If I read these instructions and the other documentation correctly, this module is only intended to work on an Oracle GeoRaster table that includes one row, is this correct? What if we have a dataset, such as a 1/3 arc second elevation grid from the USGS that will be extremely large? I it is likely possible to use GDAL to merge one very large GeoTiff, then import that into a single entry but that's certainly not optimal. We also have the issue of a dataset that doesn't necessarily fit very well into a single raster entry such as a coastal storm surge grid for the USA Atlantic and Gulf Coasts (because it will be 95% no value cells since it is only coastal regions that have values, but they we would merge into one large mostly empty raster). These are two of the datasets that Baskar is trying to work with in this effort. It is possible to either use GDAL to merge these, or even to use SDO_GEOR.mosaic in order to create a table with only one row, but that's really not our preferred method of storing data. It may become apparent that this is our only option, but we haven't decided that yet. Thanks, Bruce -----Original Message----- From: christian.muel...@nvoe.at [mailto:christian.muel...@nvoe.at] Sent: Tuesday, May 04, 2010 1:46 AM To: Baskar, Dhanapal Cc: geotools-devel@lists.sourceforge.net Subject: Re: [Geotools-devel] Proposed Mosaicing GeoRaster Module Hi Baskar, First, please do a "svn up" on trunk, I did some enhancements giving the jdbc driver a chance to cache prepared statements. Second, there is a misunderstanding of the Oracle Georaster concept. Oracle does the tiling and mosaicing for you. Looking at the test setup, there is one table called "raster" with two attributes "name" and "image". There is only one row in it. The image itself is already tiled and has pyramids. The raster data table is called raster_rdt and is created and populated by Oracle itself. SQL> select count(*) from raster_rdt; COUNT(*) ---------- 1029 There 1029 tiles in the db for pyramid levels 0,1,2 SQL> desc raster_rdt; Name Null? Type ----------------------------------------- -------- ---------------------------- RASTERID NOT NULL NUMBER PYRAMIDLEVEL NOT NULL NUMBER BANDBLOCKNUMBER NOT NULL NUMBER ROWBLOCKNUMBER NOT NULL NUMBER COLUMNBLOCKNUMBER NOT NULL NUMBER BLOCKMBR MDSYS.SDO_GEOMETRY RASTERBLOCK BLOB Looking at these attributes, you see what Oracle is doing for you. Oracle itself does the mosaicing and cropping for a given pyramid level. One big image is stored as one Oracle Raster Object. Btw, do you know www.gdal.org. This is the swiss army knife for image handling. You can use gdal_merge.py to create a big image from your tiles and import it like I do it in the GeoRasterOnlineTest class Download gdal from http://fwtools.maptools.org/, this is easiest way. Your concept is more like this one http://trac.osgeo.org/postgis/wiki/WKTRaster One Table is one image, each pyramid level has its own table. I hope I could clarify these different architectures. And finally, there is nothing bad the way you did it, but you are not using the full power of Oracle Georaster. Christian ------------------------------------------------------------------------------ _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel *************************** This message may contain confidential or proprietary information intended only for the use of the addressee(s) named above or may contain information that is legally privileged. If you are not the intended addressee, or the person responsible for delivering it to the intended addressee, you are hereby notified that reading, disseminating, distributing or copying this message is strictly prohibited. If you have received this message by mistake, please immediately notify us by replying to the message and delete the original message and any copies immediately thereafter. 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