[Geomoose-users] Geomoose-users Digest, Vol 63, Issue 2

Sat Nov 5 13:52:27 PDT 2016

Thanks for the information.  I'll have to read up on this. 

Sent from my iPad

> On Nov 4, 2016, at 2:00 PM, geomoose-users-request at lists.osgeo.org wrote:
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> Today's Topics:
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>   1. Re: caching aerial photos in MapServer (Eli Adam)
> 
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Fri, 4 Nov 2016 09:35:52 -0700
> From: Eli Adam <eadam at co.lincoln.or.us>
> To: TC Haddad <tchaddad at gmail.com>
> Cc: GeoMOOSE Users List <geomoose-users at lists.osgeo.org>
> Subject: Re: [Geomoose-users] caching aerial photos in MapServer
> Message-ID:
>    <CACqBkM8ir0iftLmx5jE77iRx_x1=kvPf1kq+7UbPJtmbEbmKXA at mail.gmail.com>
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> I just remembered that I am also assuming fcgi.
> 
>> On Thu, Nov 3, 2016 at 11:49 AM, TC Haddad <tchaddad at gmail.com> wrote:
>> Hi Tim,
>> 
>> I get the idea you are looking for the big picture of how caching can fit
>> into what you want to do. I agree with Dan that you should look into
>> MapCache.
>> 
>> Basically if you have MapCache set up in front of your MapServer, all
>> requests past first through MapCache, which first checks if the request
>> already exists in the cache, and if so, it shortcuts the process and never
>> needs to talk to MapServer, as it can serve the tile directly from the
>> cache. If an area has never been requested before, the request is
>> transferred to MapServer, which does it's thing, and passes it's result back
>> to MapCache for storage for future requests.  This model is a "cache on
>> demand" situation, which is different than "cache in advance", where you
>> might generate all the tiles possible in advance. Caching in advance is also
>> possible, but usually requires a larger amount of disk space to be available
>> than aching on demand does.
>> 
>> From your MapServer map file perspective, Your map files are set up as you
>> normally would. MapCache is an Apache module that must be enabled in Apache
>> in order for you to use it. You configure it using a Configuration XML file
>> where you point it at the MapServer services that you would like to cache.
>> 
>> From your front end user perspective, all that is different is the base URL
>> that you send them to for the cached services (MapCache base URL vs raw
>> MapServer URL). So usage for the user is totally the same as non-cache
>> usage. In my experience caching does improve performance, especially if your
>> user interface is making tiled requests, rather than single image WMS
>> requests.
>> 
>> A few other advantages of using MapCache:
>> 
>> - MapCache will allow requests of multiple tiling schemes from the same
>> cache - e.g. TMS, Google Maps, WMTS
>> - you can choose to cache an irregular subset of your imagery - for example
>> a watershed basin - and save on the disk space of all the pixels outside of
>> your basin
>> 
>> I'm sure there are more, but these are the ones that I have found most
>> handy.
>> 
>> Tanya
>> 
>> 
>> 
>>> On Thu, Nov 3, 2016 at 8:58 AM, Eli Adam <eadam at co.lincoln.or.us> wrote:
>>> 
>>> I've found that with well optimized tiffs (single YCBCR JPEG
>>> compressed tiff in the correct projection with overviews), there is
>>> essentially no time or processing spent accessing and producing aerial
>>> views.  What time is spent delivering imagery to the client is usually
>>> network transfer time which will be the same in cached and non-cached
>>> cases.
>>> 
>>> The command line tool, shp2img, can be used to give timing information
>>> from your mapfile.
>>> 
>>> Have you concluded that caching (i.e. file access and processing
>>> times) would indeed speed up your application?
>>> 
>>> MapServer or GDAL lists might be better for aerial imagery
>>> optimization, serving, and caching discussions.  Searching the
>>> archives on nabble might turn up past discussions too.
>>> 
>>> Best regards, Eli
>>> 
>>> On Thu, Nov 3, 2016 at 8:18 AM, Dan Little <theduckylittle at gmail.com>
>>> wrote:
>>>> Have you looked at mapcache? http://mapserver.org/mapcache/
>>>> 
>>>> Brought to you by the good folks at MapServer.
>>>> 
>>>> On Thu, Nov 3, 2016 at 9:50 AM, Tim Hennig <timhbellevue at gmail.com>
>>>> wrote:
>>>>> HI Everyone,
>>>>> 
>>>>> I was wondering if someone can direct me to good information regarding
>>>>> caching aerial photos in MapServer.  I know this is not a GeoMoose
>>>>> question
>>>>> pertaining to the application, but I would like to start researching
>>>>> this
>>>>> and possibly implement this sometime in the next month.
>>>>> 
>>>>> I’ve looked at the MapServer website, but I’m trying to figure out the
>>>>> process.  Can use ArcGIS cache tiles and tie it into MapServer?  Is
>>>>> there an
>>>>> add-on QGIS to cache? Etc.?
>>>>> 
>>>>> I also thought about using REST services from the county that I reside
>>>>> in,
>>>>> but the caching is not as detailed at a municipal level.
>>>>> 
>>>>> Right now the GeoMoose is using TIF images.
>>>>> 
>>>>> Tim Hennig
>>>>> Village of Bellevue
>>>>> 
>>>>> 
>>>>> 
>>>>> 
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