[GRASS-user] Working with a large number of maps

[Gerald Nelson]

When you get this all working, please post a description of the final outcome in the grass wiki. 
Thanks,
Jerry

---- Original message ----
>Date: Wed, 19 Dec 2007 15:16:10 +0200
>From: Craig Leat <craig at pid.co.za>  
>Subject: Re: [GRASS-user] Working with a large number of maps  
>To: Glynn Clements <glynn at gclements.plus.com>
>Cc: grass-user at lists.osgeo.org
>
>Glynn Clements wrote:
>> Craig Leat wrote:
>>   
>>> I have 139 high resolution images, which I need to use as a background map
>>> for some digitizing work. 
>>>     
>> How do the individual maps relate to the overall region?
>>
>> If they are (approximately) tiles, I would suggest using a
>> hierarchical approach, patching groups of adjacent tiles into larger
>> tiles, then patching the larger tiles together, so that each r.patch
>> operation has relatively few maps, and the earlier stages have
>> relatively small regions.
>>
>> The total time taken by r.patch is roughly proportional to the total
>> number of cells in the region multiplied by the number of input maps,
>> so the combination of a large region and a large number of maps will
>> be slow.
>>
>>   
>Thanks for the advice Glynn. The images are tiles and the filenames 
>follow a regular pattern, so I am able to patch blocks together quite 
>easily with a simple script. I included lots of echos in the script and 
>now I even have verbose messages ;-)   
>
>The script is running right now and making good progress...
>
>Craig
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Gerald Nelson
Professor, Dept. of Agricultural and Consumer Economics
University of Illinois, Urbana-Champaign
office: 217-333-6465 
cell: 217-390-7888
315 Mumford Hall
1301 W. Gregory
Urbana, IL 61801