Restrictions for sdo_geor.mosaic

Question

Hi All
i have a set of georeferenced images which are ready to be mosaiced , in the sense that there is no overlap or gap in between the images. Spatial Index is also created on the table . But still i get error when i do a sdo_geor.mosaic.
ORA-13419 cannot perform mosaick operation on the specified table column
All the images have the same resolution, same number of bands . is there any other restriction for the images to be mosaiced.
i have put the coverage of images on following url
http://www.geocities.com/jaleelahmed/coverage.html
each red block is one image (one row in my georaster table)
Any advice is appreciated.
Thanks
Ab

Answer 1

Ab,
The beta1 of the next release will be avaialbale in this fall. There is no officially fixed date for the next release yet. The new mosaic would be able to automatically handle this case as long as there is no overlapping. The mosaic object would be sort of sparse so that the missing image tiles would not consume any disk space.
Still, I think your project is doable using the 10g mosaic as long as the images meet the requirements outlined under the Usage Notes of SDO_GEOR.mosaic in chapter 4 of the GeoRaster manual.
To make sure you can move forward, one more question:
are those images rectified and projected into the same projection?
If so, you should be able to do the mosaic without problem.
I would recommend you divide and conquer, i.e., split the whole mosaic into several smaller mosaics (sub-areas, such as northeastern area, northwestern area, etc.) first, mosaick them separately, then mosaick these smaller mosaics into the big one as you desire.
Please note that, for the missing tiles, you will have to make-up them. But it's relatively easy:
1. call sdo_geor.createBlank with a single cell value such as zero and proper image dimentions sizes. (those blank georaster objects will not store the pixels in RDT and so will not consume space. For the definition of BLANK GeoRaster object please read chapter one of the GeoRaster manual)
2. georeference each of the blank objects properly so that they are aligned/co-located with your images correctly. (this is the place where you need much time and shall be very careful so that the blank images are georeferenced correctly and meet the requirements of sdo_geor.mosaic)
Simply for mosaic process, you have an alternative. you actually don't have to geo-spatially georeference each image by leveraging the ULT coordinate feature of GeoRaster. On other words, remove georeferencing info first, then call setULTCoordinate to reset all ULT coordinates of the images so that they are spatially properly located in the GeoRaster cell space. Then do mosaic. After mosaick, you re-georeference the mosaic image by calling sdo_geor.georeference.
Let us know if you have any problem. This project is very interesting and shall be doable.
Regards,
Jeffrey Xie