shrug-l: JPEG2000 Compression - Solution...

[Mark.Welsh at dot.state.fl.us]

Thanks to everyone (especially James Klugh), for their helpful suggestions.
Here's the deal:

The issue was not with JPEG2000 compression per se, but rather with how the
pyramids were being constructed in ArcSDE 9.1.  I was using an ArcObjects
application I wrote in 8.3, and ported over to 9.1.  There has been a
significant rework of raster entities in 9.1 and the draw speed issue is a
result of this raster rework.  In the old 8.3 days, there were three raster
pyramid load types (0 = do not build, 1 = build skip first level, and 2 =
build with first level). When we had SDE 8.3, we loaded images with build
with first level and got great draw performance.

What we noticed is that when we migrated these mosaics to SDE 9.1 and
looked at the properties in ArcCatalog, the pyramid level was "11".
Anything with 11 had snappy draw speed.  The mosaic I was having problems
with (that I loaded with my application using option 2, above) had a
pyramid level of "2".  When I rebuilt pyramids to "11", then the mosaic had
good draw performance.   I changed my application to 11 for pyramid levels
and now it creates a suitable level of pyramid structure.  Not quite sure
what all the pyramid values mean since I couldn't find any documentation on
them, but hey, it worked.

Mark


                                                                           
             Mark.Welsh at dot.st                                             
             ate.fl.us                                                     
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             11/02/2005 12:41          shrug-l: JPEG2000 Compression?      
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We have loaded some high resolution imagery (2005) into ArcSDE 9.1 (oracle)
using JPEG2000 compression (quality level 150).  We have noticed the draw
speed for this imagery is very slow.  We have the same imagery for 2003
that we loaded with JPEG compression, and it draws instantly.  Basically
the only differences is the compression type.  We have built pyramids,
analyzed the block table, used various oracle optimization techniques, but
nothing seems to work.  Anyone else out there run into this?  Any
solutions?  Thanks!

Mark Welsh
GIS Applications Coordinator
Transportation Statistics Office
Florida Department of Transportation
(850) 414-4722
mark.welsh at dot.state.fl.us

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