Mirroring effect using OSGB projection

[tbonfort]

Mirroring effect

When accessing a WMS layer in OSGB36 (British National Grid) projection, the area to the west of Scilly Islands (a group of islands off the westernmost tip of the Great Britain) appears mirrored, featuring a vertically flipped copy of Scilly Islands and South West England in the ocean. The attached screenshot serves as an illustration (true island on the right, mirrored copy on the left).

The MapCache configuration is as follows:

   <cache name="bgs_onshore2" type="bdb">
     <base>/bgs_onshore2</base>
   </cache>
   <source name="bgs_onshore2" type="wms">
      <getmap>
         <params>
            <FORMAT>image/png</FORMAT>
            <LAYERS>1</LAYERS>
            <TRANSPARENT>TRUE</TRANSPARENT>
         </params>
      </getmap>
      <http>         <url>http://maps.bgs.ac.uk/ArcGIS/services/BGS_Detailed_Geology/MapServer/WMSServer</url>
         <timeout>3600</timeout>
         <connection_timeout>3600</connection_timeout>
      </http>
   </source>
   <tileset name="bgs_onshore2">
      <metadata>
        <title>BGS Onshore Original</title>
      </metadata>
      <source>bgs_onshore2</source>
      <cache>bgs_onshore2</cache>
      <grid>BNG</grid>
      <format>PNG</format>
      <metatile>5 5</metatile>
      <metabuffer>10</metabuffer>
      <expires>86400</expires>
   </tileset>

The seeded tiles are accessed using the following URL:

http://localhost:3005/tiles?LAYERS=bgs_onshore2&TRANSPARENT=true&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&FORMAT=image%2Fpng&SRS=EPSG%3A27700&BBOX=50030.292395313,-6259.7338946798,114893.56276466,30413.824507924&WIDTH=2167&HEIGHT=1225

This has been tested using node mapcache but that as the node bindings simply act as a http shim to the mapcache core it is expected to be replicable in the other mapcache interfaces.

[tbonfort]

what happens if you access the tileset through a TMS/WMTS viewer?

[olessko]

When accessing the tileset through a TMS request no mirroring occurs, the first westernmost column contains correct tile:
tms/1.0.0/bgs_onshore2@BNG/6/0/15.png

[tbonfort]

@olessko can you send me the full mapcache.xml file please

[olessko]

Sure, please see attached.

Oles

On 7 October 2013 12:12, Thomas Bonfort notifications@github.com wrote:

@olessko https://github.com/olessko can you send me the full
mapcache.xml file please

—
Reply to this email directly or view it on GitHubhttps://github.com//issues/85#issuecomment-25797447
.

[tbonfort]

@olessko please email it to me directly (thomas.bonfort gmail.com)

[tbonfort]

I can confirm this is reproducible with the cgi, looking into it ...

[tbonfort]

@olessko can you confirm this PR fixes your issue. thanks.

[olessko]

Yes, it does. Thank you very much for your help!

[tbonfort]

applied to branch-1-2 in 6c52e3d