[mapserver-dev] Raster fliped with WMS and reprojection

[Even Rouault]

Le jeudi 12 juin 2014 14:12:58, Yves Jacolin a écrit :
> Hello,
> 
> I have a raster file in GeoTiff, EPSG:4326. I am using it in a mapfile for
> WMS services in EPSG:3857.
> 
> When zooming out I get the raster layer flipped. All other vector layer are
> ok. It seems that it occurs when the BBOX is outside the EPSG:3857
> projected bounds limitation [1].
> 
> I have another issue which may not be linked with the previous one: a
> vertical blank line appear on the left (beyon 180 degrees). However, the
> raster is showing again after the date line.
> 
> Here two requests, the first one shows the wrong result:
> *
> http://www.ifremer.fr/services/wms1?LAYERS=ETOPO1_BATHY_R&STYLES=default&FO
> RMAT=image%2Fpng&TRANSPARENT=TRUE&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&
> SRS=EPSG%3A3857&BBOX=-28066452.007098,-2465552.6274048,30754589.246699,9979
> 617.7775904&WIDTH=1503&HEIGHT=400
> 
> The second one shows the good result:
> *
> http://www.ifremer.fr/services/wms1?LAYERS=ETOPO1_BATHY_R&STYLES=default&FO
> RMAT=image%2Fpng&TRANSPARENT=TRUE&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&
> SRS=EPSG%3A3857&BBOX=-28066452.007098,-2465552.6274048,30754589.246699,9979
> 617.7775904&WIDTH=1502&HEIGHT=400
> 
> Diff:
> - WIDTH=1503
> + WIDTH=1502
> 
> This MapServer is quiet old but I can reproduce the issue with master.
> 
> If I open the raster file directly in QGIS I have some other rendering
> issue (some part of the raster are not displayed at all, but always
> different part among the zoom level (always on the left anyway).

I guess those artifacts are encountered with on-the-fly reprojection turned on 
? QGIS must have similar issues as MapServer with discontinuities at date-line 
crossing.

> 
> Log in MapServer doesn't seems to show any error.
> 
> Any idea? Should I fill a ticket with this?

Could be usefull with .map, associated input data and requests. 

> 
> Thanks,
> 
> Y.
> [1] http://epsg.io/3857

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