[ka-Map-users] tiling print service (WMS)

Wed May 10 10:12:48 EDT 2006

Bart -

Well, I expect that the ECW decompression will certainly increase your
RAM requirements!  You can't make sure the client requests the image at
native resolution - I was just trying to understand whether your test
was simple or not.  I would normally expect you to create resampled
overviews in your raster imagery, but that doesn't apply to ECW images.

I suspect there are a number of complexities involved in the ECW storage
and serving of the data, which I don't understand.  I store all my
imagery completely uncompressed - disks are cheap, too!

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: Bart van den Eijnden (OSGIS) [mailto:bartvde at xs4all.nl] 
Sent: Wednesday, May 10, 2006 10:10 AM
To: Ed McNierney
Cc: ka-map-users at lists.maptools.org
Subject: RE: [ka-Map-users] tiling print service (WMS)

Hi Ed,

the data sources are raster (ECW). There is probably resampling going on
though.

But in the case of ArcGIS as a WMS client, how can you make sure the
client requests the image at the native resolution?

Best regards,
Bart

> Bart -
>
> Are you requesting the image data at native resolution (if your 
> sources are rasters), or is there resampling going on?
>
> In normal production usage we limit users to 60 million pixels (6,000 
> x 10,000, for example) per image and easily produce those images 
> (sometimes more than one at a time) on a machine with 2GB of RAM.
>
> 	- Ed
> Ed McNierney
> President and Chief Mapmaker
> TopoZone.com / Maps a la carte, Inc.
> 73 Princeton Street, Suite 305
> North Chelmsford, MA  01863
> ed at topozone.com
> (978) 251-4242
>
> -----Original Message-----
> From: Bart van den Eijnden (OSGIS) [mailto:bartvde at xs4all.nl]
> Sent: Wednesday, May 10, 2006 10:06 AM
> To: Ed McNierney
> Cc: ka-map-users at lists.maptools.org
> Subject: RE: [ka-Map-users] tiling print service (WMS)
>
> Hi Ed,
>
> we did a quick test, 10k x 10k pixels did not finish on our machine 
> with
> 1.5 Gb and 500 Mb swap. In the end Mapserver had 1700 Mb in memory, 
> but crashed with an itnernal server error when the swap was full.
>
> How much RAM do you use in your servers for this kind of task? And 
> what kind of pixel width/height limit do you use?
>
> Thanks in advance.
>
> Best regards,
> Bart
>
>> Bart -
>>
>> RAM is cheap <g>.  Seriously, although it depends a lot on the 
>> machine
>
>> you're installing it in, that much memory (1GB) for many systems runs

>> about USD $100.  And depending on the usage level, you might just let

>> the system swap and use virtual memory for the task.
>>
>> 	- Ed
>>
>> Ed McNierney
>> President and Chief Mapmaker
>> TopoZone.com / Maps a la carte, Inc.
>> 73 Princeton Street, Suite 305
>> North Chelmsford, MA  01863
>> ed at topozone.com
>> (978) 251-4242
>>
>> -----Original Message-----
>> From: ka-map-users-bounces at lists.maptools.org
>> [mailto:ka-map-users-bounces at lists.maptools.org] On Behalf Of Bart 
>> van
>
>> den Eijnden (OSGIS)
>> Sent: Wednesday, May 10, 2006 8:12 AM
>> To: ka-map-users at lists.maptools.org
>> Subject: RE: [ka-Map-users] tiling print service (WMS)
>>
>> Hi Ed,
>>
>> but won't that consume too much memory?
>>
>> For generating a 15.000 x 15.000 pixels PNG24 image Mapserver would 
>> take about 900 Mb into memory or not?
>>
>> Best regards,
>> Bart
>>
>>> Bart -
>>>
>>> I'm not aware that a 2048x2048 pixel limit is "normal" for WMS
>> servers.
>>> That's the default limit for MapServer but it is very easily
changed.
>>> I've done that for several years and produce very large images from 
>>> single MapServer WMS requests.
>>>
>>> 	- Ed
>>>
>>> Ed McNierney
>>> President and Chief Mapmaker
>>> TopoZone.com / Maps a la carte, Inc.
>>> 73 Princeton Street, Suite 305
>>> North Chelmsford, MA  01863
>>> Phone: +1 (978) 251-4242
>>> Fax: +1 (978) 251-1396
>>> ed at topozone.com
>>>
>>> -----Original Message-----
>>> From: ka-map-users-bounces at lists.maptools.org
>>> [mailto:ka-map-users-bounces at lists.maptools.org] On Behalf Of Bart 
>>> van
>>
>>> den Eijnden (OSGIS)
>>> Sent: Wednesday, May 10, 2006 7:52 AM
>>> To: ka-map-users at lists.maptools.org
>>> Subject: [ka-Map-users] tiling print service (WMS)
>>>
>>> Hi list,
>>>
>>> can the ka-map tiling logic be used to create a WMS print service?
>>>
>>> Imagine our use case, people wanting to print on A0 paper from 
>>> ArcGIS,
>>
>>> and ArcGIS has a WMS layer for aerial photographs in it. Ofcourse 
>>> normal WMS services limit themselves to 2048x2048 pixels like
>> Mapserver does.
>>> But ArcGIS requests an image of about 15000 pixels wide.
>>>
>>> If a tiling php script could act as WMS service, and would ask for
>>> 2048x2048 tiles to the aerial photograph WMS, and stream that back 
>>> to
>
>>> the client (ArcGIS), it could be a solution. Could ka-map be used 
>>> for
>
>>> this?
>>> Would it be a lot of work?
>>>
>>> Also, is it possible to stream back the whole 15000x15000 pixels 
>>> image
>>
>>> without taking the whole thing in memory? I.e. could the script read

>>> up the tiles from disk and stream them sequentially into 1 image?
>>>
>>> Thanks in advance for some thoughts on this.
>>>
>>> Best regards,
>>> Bart
>>>
>>> _______________________________________________
>>> ka-Map-users mailing list
>>> ka-Map-users at lists.maptools.org
>>> http://lists.maptools.org/mailman/listinfo/ka-map-users
>>>
>>>
>>
>>
>>
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