[gdal-dev] tileindex performance

[christian.mueller at nvoe.at]

Hi guys, I am the developer of the gdal_retile. Using gdal_retile on  
very large images only makes sense if you plan to import your tiles  
into a jdbc database. Serving images from so many files is not  
recommended.

I tested on an AIX Box, tiling an 80 GB Erdas image. The performance  
decrease was due to the increasing number of files in the file system.  
I had about 1 million of individual files. Deleting or moving this  
file set was a reason for drinking a cup of coffee. (15 - 30 minutes).  
And we are talking here from an AIX Box having a JFS file system and  
fast server disks.

Please check this symptom in your environment, look for the number of  
files you have created and the performance.

I am interested if this symptom occurs on your platforms too.

Cheers
Christian


Quoting Elijah Robison <elijah at villagis.com>:

> Hi Nikos,
>
> I also have difficulty tiling large, high res images with gdal_retile.
> I would say our average process--a county-wide, 1-foot resolution
> ECW--takes about a month to run to completion.
>
> At first, tiles are generated with blazing speed.  But by the time the
> routine has been running for about 24-hours, it slows to a crawl.  Is
> this the symptoms you are experiencing or are you running into
> something else?
>
> I would very much love to get to the bottom of this and find a way to
> maintain the original performance throughout a tiling routine.
>
> Best, Elijah Robison
>
>
> nickos85 wrote:
>> Hi,
>>
>> I have a mapserver and a high resolution image about 4GB when i make the
>> image tiles with a size of 512x512 using gdal_retile I have better result
>> instead of a tile size of 256x256. I think the problem is on how the search
>> algorithm for the location of the tile can be improoved. Any suggestions?
>>
>> --Nikos Hatzopoulos
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