[mapserver-users] Mapcache tileset only shows sporadically in KML / Google Earth
Rahkonen Jukka
jukka.rahkonen at mmmtike.fi
Sun Jun 9 03:23:35 PDT 2013
Hi,
This is so important thing to know that it should be mentioned in http://www.mapserver.org/trunk/mapcache/seed.html
I believe I am not the only GeoWebCache users who experiment with MapCache and think that MapCache can also do seeding/reseeding/truncating for an active cache because that is the standard with GWC.
The need to use seeding tool with inative cache makes me to wonder how to implement partial updating of big cache like 1 TB in size in production environment. The service can't be stopped for truncating and reseeding. Making a copy of the active cache, truncating and reseeding the copy and finally switching MapCache to use the refreshed cache should work, but copying 1 TB of data is slow and keeping an extra terabyte on a hosted disk is costly.
I guess that by using a GeoTIFF cache it would be possible to use the seeding tool for creating a new cache from the updated areas. The tiff files in the new cache are using the same naming convention and therefore they could be copied on top of the outdated tiles in the active cache and this could happen on-the-fly. Would this work?
-Jukka Rahkonen-
________________________________________
Stephen Woodbridge wrote:
> In general, The seeder can not be run on an active cache because it does
not coordinate tile generation with apache so if they both try to create
the same tiles things can get confusing and there is a chance that an
incomplete tile might get served with both writing the resulting tile
might be damaged.
-Steve W.
On 6/8/2013 3:41 PM, John D. Evans wrote:
> Hi,
>
> Thomas Bonfort wrote on 06/06/2013:
>> As for the root issue, are your tilesets fully preseeded or are they
>> populated on demand? KML superoverlays are organized in a tree, i.e.
>> to access a tile at zoom level N you first need to access all parent
>> tiles from level 0 to N-1; on an unseeded tileset with a slow wms
>> backend this might be a very long wait. Also please check the apache
>> error log for any mapcache related messages.
>
> Thanks for the input! Sorry for the delayed reply. My tiles had been
> populated on demand but I finally found, installed, and ran
> "mapcache_seed". It's now been running for 10+ hours now (*) but I still
> get the same effect in Google Earth. (A very low-resolution view
> displays when I'm zoomed out very far, but disappears as soon as I try
> to zoom in.) Does the seeding have to be completely finished before
> Google Earth can see beyond the top-level KML tiles?
>
> Thanks again.
>
> - John E.
>
> (*) I'm running this on a fairly puny virtual machine (2 cores); I guess
> I should try seeding with 8 or 10 threads on an 8-core machine. I will
> also try limiting my zoom levels (I suspect I'm seeding 0-17 by default)
> and my spatial extent (I'm probably doing the whole globe by default --
> lots of blank tiles :-).
>
>>
>>
>> On 6 June 2013 05:19, John D. Evans <john.evans at gst.com
>> <mailto:john.evans at gst.com>> wrote:
>>
>> Hello,
>>
>> Not sure my earlier query made it to the list.
>>
>> I'm using MapCache to serve for some satellite image products. It
>> sort of works: the tms and wmts browsers at /mapcache/demo show
>> full coverage of my data area, and let users zoom in to see full
>> resolution image mosaics. But the KML superoverlay (my reason for
>> using MapCache) only displays in Google Earth when I'm zoomed very
>> far out (so that the entire globe is not much bigger than a golf
>> ball on my screen). If I zoom in, the image usually disappears;
>> though sometimes when zoomed in I do see [only] the right (east)
>> half of my tileset, at a very low resolution.
>>
>> Do you see anything wrong with my mapcache.xml (below)?
>> Is there anything else I should be checking?
>>
>> (I'm using a simple disk cache in /tmp, with mod_mapcache from the
>> Ubuntu libmapcache 1.0.0-3 package; Mapserver 6.2.1 is on the same
>> machine, running in 64-bit Ubuntu 12.04. Mapserver works fine, and
>> reports no errors [I think]. My client is Google Earth 7.)
>>
>> Thanks for taking a look,
>>
>> - John D. Evans
>> GST, Inc / Greenbelt, MD
>>
>> Below is my mapcache.xml file (actually an excerpt of it:
>> the real one has more tilesets and sources).
>>
>> <mapcache>
>> <metadata>
>> <title>my mapcache service</title>
>> <abstract>woot! this is a service abstract!</abstract>
>> </metadata>
>>
>> <cache name="disk" type="disk">
>> <base>/tmp</base>
>> <symlink_blank/>
>> </cache>
>>
>> <format name="PNG_BEST" type ="PNG">
>> <compression>best</compression>
>> </format>
>> <format name="PNG_FAST" type ="PNG">
>> <compression>fast</compression>
>> </format>
>>
>> <source name="CSPP_CloudPhase" type="wms">
>> <http>
>> <url>http://localhost/cgi-bin/mapserv?</url>
>> </http>
>> <getmap>
>> <params>
>> <FORMAT>image/png</FORMAT>
>> <LAYERS>iicmocp_daily</LAYERS>
>> <MAP>/raid/maps/viirs.map</MAP>
>> </params>
>> </getmap>
>> </source>
>>
>> <tileset name="CSPP_Cloud_Phase_EDR">
>> <metadata>
>> <title>VIIRS Cloud Phase from NASA GSFC DRL</title>
>> <abstract>Detailed description goes here</abstract>
>> </metadata>
>> <source>CSPP_CloudPhase</source>
>> <cache>disk</cache>
>> <format>PNG</format>
>> <grid>WGS84</grid>
>> <metatile>2 2</metatile>
>> <expires>3600 <tel:3600></expires>
>> <auto_expire>3600 <tel:3600></auto_expire>
>> <!-- <metabuffer>10</metabuffer> -->
>> </tileset>
>>
>> <default_format>PNG_FAST</default_format>
>>
>> <service type="wms" enabled="true">
>> <full_wms>assemble</full_wms>
>> <resample_mode>bilinear</resample_mode>
>> <format>PNG_FAST</format>
>> <!-- <maxsize>4096</maxsize> -->
>> </service>
>>
>> <service type="wmts" enabled="true"/>
>> <service type="tms" enabled="true"/>
>> <service type="kml" enabled="true"/>
>> <service type="gmaps" enabled="true"/>
>> <service type="ve" enabled="true"/>
>> <service type="demo" enabled="true"/>
>>
>> <lock_dir>/tmp</lock_dir>
>> <errors>report</errors>
>> <threaded_fetching>true</threaded_fetching>
>>
>> </mapcache>
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