[FWTools] gdal JPEG2000 driver and shp2img , MapServer

[Trent M Hare]

You can now create giant Tiffs (bigtiff) using GDAL and then convert to 
jpeg2000 using the free jpeg2000 Kakadu binaries. Last year Kakadu 
introduced support for bigtiffs and has for a while had the ability to 
copy the geotiff header into the Jpeg2000 file (making a geoJpeg2000). 

This will work for only 8 or 16bit images (not 32bit float or higher).

example for converting a GeoTiff (lossless):
> kdu_compress -i input_geo.tif -o output_geo.jp2 Creversible=yes 
Clayers=16

leave off Creversible=yes to incur a lossy conversion (w/ default quality) 
which should result in a smaller file size. I bet it would be hard to see 
that any loss has occurred using the default but that can also be changed.

Clayers - I'm not a familiar with but it was used on the example page. I 
assume it is the number of levels. So for smaller files this might be too 
many?

good luck,
Trent





From:
"karsten vennemann" <karsten at terragis.net>
To:
<fwtools at lists.maptools.org>
Date:
02/17/2011 10:46 PM
Subject:
Re: [FWTools] gdal JPEG2000 driver and shp2img , MapServer
Sent by:
fwtools-bounces at lists.maptools.org



Thanks Frank,

> I'm not sure why the FWTools MapServer is not finding the 
> JP2ECW driver if you have it with gdalinfo.  However, your 
> project isn't going to work the way you want anyway.  There 
> is no way to assemble a single map in memory to large that it 
> will be 500MB when jpeg2000 compressed.  You are going to 
> need to come up with a scheme to produce the final result in 
> chunks with MapServer and then assemble them into a final 
> product as a post processing step.

Ok I was not aware that all of this is happening in memory ;) with 
JPEG2000 format... I could script the creation of tiles via MapServer and 
assemble the result later yes... but
 
> Note that the JP2ECW driver only supports writing large 
> JPEG2000 files if you set the LARGE_OK creation option on, 
> and you are required to have a valid license to do so.  So I 
> also don't think you ought to be using the JP2ECW driver to 
> assemble your final jpeg2000 product.

... then this fact does not really leave that as an option... 

..there seems to be not really many (any?) formats or libraries that 
freely support creation of huge images / compression of images I guess . 
Or are there any other good OS alternatives to create compressed imagery ?

One option would be to convince my client ot accept a collection of tiles 
as tiff e.g. which would be a better way to do this anyway ...
Cheers
Karsten

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